Tag Archives: vegetable

Compatibility: Pesticides and natural enemies of pests

Green insect with lacey wings
Lacewings (especially larvae; this one is an adult) are great natural enemies of pests. You want to keep them happy and healthy!

Natural enemies of pests are going to help you out with pest control, so when you are applying pesticides, it’s in your best interest to choose products that will have the least impact on them. Two quick points before we get into details for where to find this information:

  1. Remember that the information in this post is not a substitute for a pesticide label. The label is the law, and you must read and follow the label of any pesticide you are using. Laws and labels change. It is your responsibility to use pesticides legally. Trade names used here are for convenience only; no endorsement of products is intended, nor is criticism of unnamed products implied. For questions about pesticide use, regulations, and safety, contact the Cornell Pesticide Management Education Program: pmep_webmaster@cornell.edu.
  2. A great way to protect natural enemies is by following the steps for IPM. Preventing pests (e.g., through cultural strategies and exclusion), scouting to detect pests early when populations are low, and proper identification of pests will help you reduce your need to use pesticides and can save you money. Win win!

Ok, let’s assume you’re doing good IPM and you’ve gotten to the point where you need to choose a pesticide. How do you make the best choice for protecting natural enemies? Here are a few options. (Note that I did post about this about 2 years ago. I’ve learned more, so I thought an update would be in order.)

Read the label

This should go without saying. You should be doing this anyway when you are considering using a pesticide. The label may contain information about the compatibility of a pesticide with either natural enemies or pollinators. And of course it will contain important information about how to minimize risks to yourself and the environment when you use it.

EIQ

EIQ stands for Environmental Impact Quotient. You can read more details on the NYSIPM website, but in a nutshell the EIQ puts a number on the risks of pesticides at the rates they are applied in the field. You can use the EIQ calculator on our website to compare these numbers for different pesticides. The higher the number, the higher the risk. There are different components to the EIQ; risks to consumers, workers, and the environment (ecological). The ecological risk will include risks to natural enemies (as well as fish, birds, and bees).

Pocket IPM Greenhouse Scout App

The Greenhouse Scout app provides information for doing IPM in greenhouses, including pest insects, beneficial insects, application technology, and pesticide interactions. It also gives you a place to record scouting results and track product applications.
A screenshot from the home screen of the Pocket IPM Greenhouse Scout App. You can find information about compatibility with natural enemies under either “Beneficials” or “Pesticide Interactions”.

Especially if you are growing in a greenhouse and releasing a lot of natural enemies, you may find this app helpful. In addition to providing information about compatibility of pesticides with arthropod natural enemies you may be releasing, you can also use it to help you keep records of scouting and product applications.

 

Cornell Guidelines

If you are a commercial producer, hopefully you are already utilizing the Cornell Guidelines, as they are a wealth of information on many subjects. At least some of them also include information on the toxicity of different pesticides to natural enemies. For example, if you have the grape guidelines, check out Table 4.2.2 for insecticide toxicity to natural enemies.

Websites and apps from companies that produce natural enemies

Companies that sell natural enemies (especially predatory and parasitoid arthropods for greenhouse pest control) have an interest in making sure that customers don’t inadvertently kill the natural enemies they buy with pesticides they are applying. I am aware of searchable databases or charts describing pesticide compatibility from four companies that sell (mostly) arthropod and nematode natural enemies: Agrobio, Biobest, BioWorks, and Koppert. If you know of some I’ve missed, please let me know! There are of course other companies that supply natural enemies. Here I’m focusing on resources that help you choose pesticides to conserve natural enemies.

Agrobio

This website is also available as an app for Android (but not Apple) devices. To use it, start by clicking Organisms selection and choose the natural enemies you want to conserve. Then, click Ingredients selection and choose the pesticides you are thinking about applying. You can only search active ingredients, not product names. Finally, click Query. Use the legend to help you interpret the table that’s produced.

Biobest

This website is also available as an app for Android and Apple devices. Use either the Active ingredient or the Commercial product tab to select pesticides by active ingredient or trade name. Then, search for the name of the Beneficial organism you want to conserve. Note that there are a lot of pesticide/natural enemy combinations for which toxicity data just aren’t available. If you select a pesticide, then natural enemies for which no data are available will be grayed out in the Beneficial organism list. As you check boxes next to pesticides and natural enemies, a chart is automatically generated. The legend includes keys for information on toxicity (to natural enemies and bumble bees), application methods, and persistence of the product. You can generate a pdf of your results, but it won’t include the legends.

BioWorks

Check out this resource that summarizes the compatibility of BioWorks biopesticides with arthropod and nematode natural enemies.

Koppert

This website is also available as an app for Android and Apple devices. Start by entering the name of the Beneficial organism you want to conserve. You can search by either the Koppert product name, or the Latin (scientific) name, but you can’t select from a drop-down menu. Just start typing. Then, choose the Agent (pesticide you are considering applying), by either trade name or active ingredient. Again, you need to know the name; you can’t select from a drop-down list. Start typing, and then check the box next to the product you are interested in. Click Results and be sure to click on ‘Legend’ at the bottom to help you interpret the table. There is also a more complete explanation of information in the legend under Info.

Some caveats about these websites

Admittedly, finding information about conserving natural enemies that are not commercially available for release (e.g., in greenhouses) has some challenges. These websites tend to focus on what you can buy and release, rather than on what may be naturally occurring in a field. Although sometimes there is some overlap. These apps/websites don’t include all natural enemies, and data aren’t available for all natural enemy/pesticide combinations. Also, these websites/apps usually list natural enemies by scientific names. Do you know what the scientific name of a lacewing is? I didn’t before I started this job!

To help with this last barrier, I created a chart (also below) to help you figure out what scientific names you should look for on these websites/apps if you want to conserve a particular natural enemy. It also includes information about which pests the natural enemies target, whether they are commercially available, and whether they are naturally occurring (not necessarily native) in NY.

Arthropod and nematode natural enemies

Can I buy them? Found in NY? If I want to conserve this beneficial arthropod… (whose scientific name is…) that helps me control… I should look for these names on the compatibility apps: 
yes yes aphid midges Aphidoletes aphidimyza aphids Aphidoletes aphidimyza
some yes beetles that are predators (for example, rove beetles, ground beetles, and others) Coleoptera is the scientific name of the insect group that includes all beetles. The following families are generally predatory: Coccinellidae (lady beetles), Carabidae (ground beetles), Staphylinidae (rove beetles), Cantharidae (soldier beetles), Melyridae (flower beetles) many insect pests Coleoptera is a beneficial insect listed on at least one compatibility app. However, some coleoptera are pests. And, since this is such a broad group, the compatibility information provided may not be correct for all beneficial beetle species.
yes hover flies, syrphid flies Syrphus spp, and many, many others aphids Syrphus spp.; Syrphus corollae; Episyrphus balteatus
some yes lacewings Chrysoperla spp. and some others aphids, insect eggs, small larvae Chrysopa carnea = Chrysoperla carnea; Chrysoperla spp.
some yes lady beetles Coccinellidae aphids, mites, small insects, insect eggs Coccinelidae, Coccinella 7-punctata, Hippodamia convergens
some yes minute pirate bug Orius insidiosus insect eggs, small caterpillars, thrips, mites, aphids Orius laevigatus may be a reasonable proxy; Orius spp.; Orius insidiosus
yes yes nematodes Steinernema spp., Heterorhabditis spp. thrips, fungus gnats, shore flies, some grubs Nematodes (note that this is a very broad category and it’s possible there are differences among species), Heterorhabditis bacteriophora, Steinernema, Steinernema feltiae, Steinernema carpocapsae
some yes parasitoid wasp Aphidius spp. aphids Aphidius spp., Aphidius colemani, Aphidius matricariae, Aphidius ervi
some yes parasitoid wasp Eulophidae, Diglyphus spp. leafminer larvae Diglyphus isaea
yes yes parasitoid wasp Braconids, Dacnusa sibirica leafminers Dacnusa sibirica
yes parasitoid wasp Aphelinidae, Aphelinus semiflavus aphids on potatoes Aphelinus abdominalis or Aphelinus mali may be reasonable proxies
yes yes predatory gall midge Feltiella acarisuga spider mites Feltiella acarisuga
some yes predatory mites Amblyseius (= Neoseiulus) fallacis, Typhlodromus spp., and probably others thrips, whitefly, pest mites; may vary among natural enemy species Amblyseius californicus, Amblyseius cucumeris, Amblyseius swirskii, Phytoseiulus persimilis are sold commercially and may be good proxies for the pesticide compatibility of naturally-occurring predatory mites
yes yes spined soldier bug Podisus maculiventris many immature insects, including many species of caterpillars Podisus maculiventris
 

some

some trichogramma wasps Trichogramma spp. moth eggs Trichogramma spp., Trichogramma brassicae, Trichogramma cacoeciae, Trichogramma evanescens, Trichogramma pretiosum

Other species of interest…

Can I buy them? Found in NY? If I want to conserve this beneficial insect… (whose scientific name is…) that helps me control… I should look for these names on the compatibility apps: 
yes yes bumble bee Bombus spp. NA – pollinator Bombus spp., Bombus terrestris
yes yes European honey bee Apis mellifera NA – pollinator Apis, Apis mellifera

Notes:

Different strains or populations of these natural enemies are sold by different companies and each population may differ from natural populations. Each company is most likely to report compatibility data that applies to their population. It’s not perfect, but it’s a start.

When the first word in the scientific name of an insect (e.g. Trichogramma) is followed by the designation ‘spp.’, it means multiple species that all belong to the same genus. Some compatibility information is given for only the larger group (e.g., Aphidius spp. or Syrphus spp.).

Natural enemies that are pesticides (active ingredients are microorganisms, i.e., fungi, bacteria, viruses)

If I want to conserve this microbial natural enemy… (whose scientific name is…) that helps me control… I should look for these names on the compatibility apps: 
Bt Bacillus thuringiensis (various strains are available, and they control different pests) many caterpillars and some immature beetle and fly pests (target pest varies by strain) Bacillus thuringiensis
entomopathogenic fungus Paecilomyces fumosoroseus = Isaria fumosorosea, Beauveria bassiana, Metarhizium anisopliae (= M. brunneum) (various strains) many insects (target pest depends on fungal species and strain) Paecilomyces (=Isaria) fumosoroseus, Beauveria bassiana, Metarhizium anisopliae (= M. brunneum)
fungi that attack plant diseases there are multiple species, including Trichoderma harzianum (several strains) Plant pathogens (the target pathogen depends on the fungal strain) Trichoderma harzianum T-22 is the only fungal natural enemy I found on these apps, so far. It is unlikely that its compatibility is representative of other fungi that are natural enemies.

Notes:

Different strains or populations of these microorganisms are sold by different companies and each of these populations may differ from natural populations. Each company is most likely to report compatibility data that applies to their population. It’s not perfect, but it’s a start.

In these apps/websites, microbial active ingredient may be listed as the natural enemy (e.g., Paecilomyces fumosoroseus on Biobest website), but sometimes it’s only listed as a pesticide active ingredient. For compatibility of biopesticides with chemical pesticides, you should start by reading the label, then seek information provided by the manufacturer.

All tables were assembled by Amara Dunn, NYSIPM using information from Natural Enemies of Vegetable Insect Pests (Hoffman & Frodsham) and were last updated January 2020.

Give it a try!

Imagine you were considering using one of the following active ingredients:

abamectin

acequinocyl

fenpyroximate

…to control spider mites. (Of course, before you did this, you’d read the labels and be sure that the use you were considering was legal!) If you were concerned about hurting parasitoids that help with aphid control (for example, the species Aphidius colemani and Aphidius ervi) which of these active ingredients would be the best choice (from a compatibility standpoint)?

 

Go ahead!

 

Look it up!

 

A note about microorganisms as natural enemies

Green leaf with blue rectangles with smiling faces representing microbes as natural enemies of the pest microbes (yellow rectangles with shocked faces). The blue microbes are producing blue droplets (representing antimicrobial compounds).
Microbes used to control pests are biopesticides. In this conceptual diagram, the happy blue microbes are producing antimicrobial compounds that are killing the plant pathogens (represented by yellow rectangles with shocked faces).

There are a few “natural enemies” on this chart that are actually biopesticides, and I have listed them separately. Remember that microorganisms (fungi, bacteria, viruses) that are natural enemies of pests are biopesticides. A few of them can be found in the websites/apps summarized above. There are two compatibility questions when it comes to using biopesticides with living microorganisms as active ingredients: (1) Will this biopesticide harm other natural enemies (e.g., predators and parasitoids)? and (2) Will the living microbe in this biopesticide be killed by other pesticides I might use? The websites/apps have some information about the compatibility of biopesticides with arthropod natural enemies. If you’re wondering about the compatibility of biopesticides with other pesticides, that may be a topic for another post (so many posts to write, so little time!). I’ll just offer two quick pieces of advice here:

  1. Read the label of the biopesticide. If it doesn’t contain compatibility information (for use with other pesticides) or doesn’t answer your questions about compatibility with other natural enemies, contact the manufacturer to get your questions answered.
  2. If you happen to be using one of their products, BioWorks describes the compatibility of their products with other pesticides, and this information is linked to individual product pages.

And what about the bees?

Take a look at the resources created by the Pollinator Network @ Cornell. They have prepared decision-making guides for several crops already, with more to come.

 

This post was written by Amara Dunn, Biocontrol Specialist with the NYSIPM program. All images are hers, unless otherwise noted.

How do biofungicides fit in vegetable disease management? An update after Year 2

Healthy squash plants, just starting to flower in the foreground, with a field and barn in the background.
Some of the squash plants in one of our 2019 field trials looking at the role of biofungicides in managing cucurbit powdery mildew.

We have been working on a 2-year project funded by the New York Farm Viability Institute to look at adding biofungicides to the management of two vegetable diseases: cucurbit powdery mildew and white mold. In addition to summarizing results from Year 1 of the trial, previous blog posts also covered some of the details about how to best use the biofungicides we’re testing. During the summer of 2019, we completed our second year of trials. The numbers have all been crunched, and here’s a summary of what we learned. If you want to read all the nitty gritty details, a lengthy full report from Year 2 is available here.

Project goals

During the second year of this project, we wanted to answer a few questions for growers:

  1. Can you replace some conventional fungicide applications for cucurbit powdery mildew in winter squash with one of three OMRI-listed biofungicides (LifeGard, Regalia, or Serifel) while maintaining disease control, crop quality, and yield?
  2. Can you get better control of white mold in green beans by Contans prior to planting, and Double Nickel at bloom?
  3. What are the costs (versus benefits) of using these biofungicides in these ways?
  4. Can NDVI sensors help us detect disease early? Can they help us detect differences in plant health as a result of using biofungicides?

White mold – what we did

This table summarizes the white mold treatments in green beans. Replicated plots were treated with Contans in the third week of May, prior to planting; Double Nickel when snap beans were at 10% bloom (late June or early July) and 7 days later; both Double Nickel and Contans; or neither. Treatments are summarized below.

Timing Non-treated Contans Double Nickel Contans + Double Nickel
Pre-plant Contans
(2 lb/A)
Contans (2 lb/A)
10% bloom Double Nickel LC (2 qt/A) Double Nickel LC (2 qt/A)
7 days later Double Nickel LC (2 qt/A) Double Nickel LC (2 qt/A)

White mold – what we saw and what it means

There was very little disease in the white mold trials on either collaborating farm in 2019. This is great news for the collaborating farms, but it means that we couldn’t answer our question about whether using both Contans and Double Nickel in a single season would improve control of white mold. Sarah Pethybridge did three years of efficacy trials with Double Nickel and other OMRI-approved products. In small plot trials with uniform disease pressure Double Nickel was as effective as the conventional fungicides it was compared to in reducing disease. You can read about her results here.

Cucurbit powdery mildew – what we did

We conducted the cucurbit powdery mildew trials on one farm in Eastern NY and on research farms on Long Island and in Western NY, always using the bush acorn squash variety ‘Honey Bear’. This table summarizes the treatments we compared. Essentially, we started with two early biofungicide sprays, then shifted to rotating products when disease was detected. But, in some treatments we replaced the scheduled conventional product with a biofungicide every other week. The biofungicides we looked at were the same as last year: LifeGard, Regalia, and Serifel. We compared these treatments to both a regular conventional fungicide program and a “Conventional + skip” program where we just skipped every other conventional fungicide. And, we included an organic program with traditional OMRI-listed products plus the biofungicides. Important note: Luna Experience is NOT allowed for use on Long Island. We used it in a research plot in order to be able to make comparisons to trials conducted in other parts of the state. You can learn more about fungicide options for managing cucurbit powdery mildew here, and here.

Date Non-treated Conventional Conventional + skip Conventional + LifeGarda Conventional + Regaliaa Conventional + Serifelb Organicab 
~14 days before disease LifeGard WG (4 oz/100 gal) Regalia (2 qt/A) Serifel

(8 oz/A)

LifeGard WG (4 oz/100 gal)
~7 days before disease LifeGard WG (4 oz/100 gal) Regalia (2 qt/A) Serifel

(8 oz/A)

LifeGard WG (4 oz/100 gal)
First disease detection Vivando (15 fl oz/A) Vivando (15 fl oz/A) Vivando (15 fl oz/A) Vivando (15 fl oz/A) Vivando (15 fl oz/A) MilStop (3 lb/A)
+7-10 days Luna Experiencec (10 fl oz/A) LifeGard WG (4 oz/100 gal) Regalia (2 qt/A) Serifel

(8 oz/A)

Serifel (8 oz/A)
+14-17 days Quintec (6 fl oz/A) Quintec (6 fl oz/A) Quintec (6 fl oz/A) Quintec (6 fl oz/A) Quintec (6 fl oz/A) Suffoil-X (1% v/v)
+21-24 days Vivando (15 fl oz/A) LifeGard WG (4 oz/100 gal) Regalia (2 qt/A) Serifel

(8 oz/A)

MilStop (3 lb/A)
+28-31 days Luna Experiencec (10 fl oz/A) Luna Experiencec (10 fl oz/A) Luna Experiencec (10 fl oz/A) Luna Experiencec (10 fl oz/A) Luna Experiencec (10 fl oz/A) Serifel (8 oz/A)
+35-38 days Quintec (6 fl oz/A) LifeGard WG (4 oz/100 gal) Regalia (2 qt/A) Serifel

(8 oz/A)

Suffoil-X (1% v/v)

a LifeGard and Regalia were tank mixed with Nu Film P (1 qt/100 gal)

b Serifel was tank mixed with EcoSpreader (4 fl oz/100 gal) when applied at spray volumes of 30 to 40 gal/A.

c Luna Experience is not allowed for use on Long Island. The Long Island trial was conducted on a research farm.

 

We summarized disease severity on multiple dates over the season by calculating the area under the disease progress curve (AUDPC). This value describes with a single number how quickly disease developed and how bad it got. We also measured NDVI using a GreenSeeker as a way to quantify how green and healthy the leaves were. At the end of the season, we collected yield and Brix data.

Cucurbit powdery mildew – what we saw

Not surprisingly, there was some variability among sites. But at two sites disease severity was not statistically different when we compared the standard weekly conventional fungicide program to skipping every other fungicide spray. This was disappointing, since we were expecting more severe powdery mildew from extending the spray interval, providing room for the biopesticides to improve control. However, in the Long Island trial, although powdery mildew was more severe when the spray interval was extended, applying a biopesticide during the skip week did not improve control.

For the most part, replacing alternate conventional fungicides with biofungicides resulted in disease levels that were somewhere between the conventional fungicide program and the non-treated control. At two sites LifeGard and Serifel performed slightly better than Regalia. To keep this post a reasonable length, we’re only showing results from the Long Island trial, here.

Bar graph showing the amount of disease observed in each treatment in the Long Island trial. Alternating LifeGard, Regalia, or Serifel with conventional fungicides resulted in disease levels similar to skipping every other conventional fungicide. But skipping every other conventional fungicide did not result in statistically worse disease than the full fungicide program. The costs per acre of the conventional, conventional + skip, organic, conventional alternated with LifeGard, conventional alternated with Regalia, and conventional alternated with Serifel treatments were $204, $114, $274, $207, $268, and $348, respectively.
In the Long Island trial, the conventional, conventional + skip, and all three of the conventional/biofungicide programs provided pretty good powdery mildew control. The organic program was still better than the non-treated control. This graph shows only disease on the upper surface of the leaves (AUDPC = area under the disease progress curve). The black lines on each bar show one standard error above and below the mean value for that treatment. Bars with the same letter are not statistically different from each other. This graph also shows the cost (per acre) of the cucurbit powdery mildew fungicides for each treatment above each bar.

The above graph shows a summary of disease on the upper leaf surface over the whole season. We’re not reporting the data here, but if you look at disease ratings on individual dates or on the lower surface of the leaves, skipping every other fungicide or alternating conventional fungicides with biofungicides were not as good as the weekly conventional fungicide program.

At all three sites, yield was not statistically different when we compared the standard weekly conventional fungicide program to skipping every other fungicide spray. There were no statistically significant differences in yield in the Eastern NY trial, and few differences in the Western NY trial. In both trials, when Regalia was alternated with conventional fungicides the yield was slightly but not significantly lower than the conventional/LifeGard and the conventional/Serifel treatments. In the Long Island trial, only the full conventional treatment and treatments that included LifeGard or Regalia had significantly higher yields than the non-treated control. Again, we’ll show just the data from Long Island to keep this story briefer.

Bar graph showing the average weight of marketable fruit harvested from each treatment in the Long Island trial. The heights of the bars are fairly similar, but the bars representing the conventional, conventional/LifeGard, and conventional/Regalia treatments are the tallest. The value per acre of the marketable fruit harvested from the conventional, conventional + skip, organic, conventional/LifeGard, conventional/Regalia, and Conventional/Serifel treatments is $37,837, $46,335, $42,550, $38,561, $48,022, $45,661, and $43,862, respectively.
Yields from all treatments in the Long Island trial were pretty high. The black lines on each bar show one standard error above and below the mean value for that treatment. Bars with the same letter are not statistically different from each other. The yield per plot of 12 plants was extrapolated to the yield per acre (assuming 6 ft between rows and 2 ft between plants within rows, resulting in 3,620 plants/A) and used to estimate the average grocery store value (per acre) of each treatment, shown above each bar. The value of the organic treatment (*) was not adjusted to account for presumably higher prices for certified organic produce.

Our data did not suggest that NDVI readings taken with the GreenSeeker were a good replacement for visual scouting, or that this was a good tool for detecting differences in plant health among treatments. When NDVI readings differed among treatments, powdery mildew symptoms were readily evident. The most substantial differences in NDVI values among treatments were in the Long Island trial, where both the non-treated control and the organic treatment had much lower average NDVI values over the season.

On the whole, Brix were unaffected by powdery mildew management strategy. The only statistically significant differences in Brix values among treatments were in the Eastern NY trial where the conventional/LifeGard treatment had significantly lower Brix than the conventional/Serifel treatment.

Cucurbit powdery mildew – what it means

When the full conventional fungicide program didn’t result in statistically better disease control than skipping every other spray at 2 of the 3 sites, it’s not possible to say whether or not the biofungicides were good replacements for conventional fungicides against powdery mildew. However, they did not prove to be in the Long Island trial. Our results did not suggest that measurement of NDVI values with a GreenSeeker should replace visual scouting for cucurbit powdery mildew.

Depending on the trial location (and accompanying variations in spray schedules and rates), replacing some conventional fungicides with biofungicides ranged from slightly less expensive than the full conventional program to more than twice the cost. Although in most cases there were no statistically significant differences in the value of the crop between the conventional/biofungicide programs and the full conventional program, the numerical value of the marketable crop ranged from being slightly higher (LifeGard alternated with conventional fungicides on Long Island) to lower (all other biofungicide treatments). Again, the lack of statistically significant differences between the full conventional spray program and the conventional spray program with skips in 2 of the 3 trials makes any conclusions about the economics of replacing some conventional fungicides with biofungicides, tentative, at best. There’s a lot of room to fine-tune incorporation of biofungicides into spray programs to maximize cost effectiveness.

Recall from last year’s results that we did not detect any benefit from adding biofungicides to a full cucurbit powdery mildew fungicide program. So if you’d like to use biofungicides for cucurbit powdery mildew, replacing a conventional fungicide application or two is probably a better way to go. If you’ve tried this, we’d love to hear how it worked for you!

 

Remember that the information in this post is not a substitute for a pesticide label. The label is the law, and you must read and follow the label of any pesticide you are using. It is your responsibility to use pesticides legally.

 

This post was written by Amara Dunn (NYSIPM) and Meg McGrath (Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University). Thank you to the New York Farm Viability Institute for funding.

Creating habitat for beneficial insects: Time, money, and weeds

On the left is a picture of a woman in a sundress and straw hat standing in the middle of a sunny sunflower field with her arms raised in the air. Written at the top of the picture is the title “What I thought establishing habitat for beneficial insects would be like…”. On the right is a picture of three people, either on their hands and knees or bending over, pulling weeds (including dandelions) that are several feet tall. This picture has the title: “What it’s actually like.”In December, I updated you on how perennial wildflowers and grasses were establishing in our beneficial insect habitat plots during the 2019 growing season. As I wrote that post, I quickly realized that there was too much good information for just one post. So here’s the rest of the story when it comes to plant establishment – time, money, and weeds.

Before I get started, below is a quick reminder of what our treatments were. You can read all the details here.

Treatment Description
A Spring transplant, no mulch
B Spring transplant with mulch
C Spring direct seed
D Buckwheat cover crop, then fall transplant
E – control Whatever was growing there, just keep it mowed
F Soil solarization, then fall direct seed
G Herbicide and tillage, then fall direct seed

Weed control

One thing that has surprised me about this project (although others certainly gave me fair warning) was how big a role weed management plays in establishing habitat for beneficial insects. It’s definitely still a struggle in our plots.

Bryan Brown did weed assessments for us in May and September of 2019. The graph below shows the average percent of the area of each plot covered by either weeds (orange) or beneficial habitat flowers and grasses (blue).

Bar graph shows the average percent of plots covered with either weed or beneficial habitat plants in May 2019. Weed control in the treatment (B) where transplants were mulched had the best weed control. The worst weed control was in treatment D, where seedlings were planted in Fall 2018 after a buckwheat cover crop.
Mulching provided the best weed management when plots were assessed in May of 2019. Each bar shows the average of four plots per treatment, and has an error bar showing variation among these plots (one standard error above or below the average for the treatment).

This was before we did any hand-weeding. By far, the plots that were mulched in Spring 2018 (treatment B) had the fewest weeds compared to beneficial habitat plants. You’ll also notice that in May there were still relatively few weeds in the plots where we tried to deplete the weed seed bank in the soil through solarization (treatment F) or repeated herbicide and tillage (treatment G).

Picture on the left is of treatment B (Spring transplant and mulch) and shows small wildflower plants surrounded by mulch and few weeds. The middle picture shows treatment C (spring direct seed), a weedy plot. The picture on the right shows treatment F (solarization and fall direct seed), where you can still see at least 50% of the plot is bare soil, although many small and a few larger weeds are visible.
What some of the plots looked like on May 16, 2019 when Bryan did the weed assessment.

By September 2019, the spring transplant treatments looked even better. Our wildflowers grew well during 2019 (with the help of some extra hand weeding). The plants we transplanted in Fall 2018 are still struggling and not nearly as large as the wildflowers in treatments A and B. I think this may have more to do with the weed competition they experienced that first fall (when we couldn’t plant for a few weeks after the buckwheat was mowed) than transplant timing. Hopefully they will catch up.

Picture on the left is of treatment A (spring transplant, no mulch) and shows tall wildflower plants with some weeds. The middle picture shows treatment B (Spring transplant and mulch), full of large wildflowers and few weeds. The picture on the right shows treatment D (buckwheat and fall transplant), where the wildflower plants are much smaller, there are more weeds, and some bare ground is visible.
What some of the plots looked like on September 19, 2019 when Bryan did the weed assessment.

There are still a lot of weeds in the direct-seeded treatments (C, F, or G). Remember that our weed management strategy in these plots is repeated mowing to control annual weeds. Over time, the perennial wildflowers and grasses should take over. But it’s not supposed to be a quick method.

Bar graph shows the average percent of plots covered with either weed or beneficial habitat plants in September 2019. Weed control in the treatment (B) where transplants were mulched still had the best weed control. The worst weed control (besides the control plot where no beneficial habitat plants were planted) was in the three treatments using spring or fall direct seeding (C = spring direct seeding, F = soil solarization and fall direct seeding, G = herbicide and tillage with fall direct seeding).
Spring transplant treatments (A and B) looked the best after their second full growing season. The fall transplants (D) had more weeds, but these plants also have been in the ground for one less growing season. I’m still hoping they will catch up. Each bar shows the average of four plots per treatment, and has an error bar showing variation among these plots (one standard error above or below the average for the treatment).

Effort

Most of the treatments we are comparing required much less work in their second year (2019) than in their first (2018). The exception is that we spent a lot more time hand weeding treatment D (buckwheat cover crop followed by fall transplanting) in 2019. Although we weeded the two spring transplanted plots the same number of times in 2019 (twice), it took longer to hand weed the plots without mulch. I’m not surprised. If you’re looking for the right establishment method for your project, you really need to ask yourself how much help you have available and when. If you can get a lot of people excited about helping you install the planting, but worry about getting consistent volunteers year after year, mulch may be the right choice for you. In the direct seeded treatments (C – spring; F – fall following solarization; G – fall following herbicide and tillage), the time input for 2019 was mowing, which was relatively quick. And we did just a little hand weeding of perennial weeds.

Bar graph shows time (in person hours) spent on each treatment for both 2018 (in blue) and 2019 (in orange). The tallest bars are for treatments A, B, and D, but most of the bar for treatment B is blue (representing transplanting, mulching, and hand weeding in 2018). For treatment D, half the bar is orange (representing hand weeding in 2019). Treatment A shows more orange than treatment B, but less than treatment D.
Transplanting (treatments A, B, and D) still takes more time than direct seeding, but the extra time we spent mulching in 2018 paid off in 2019 when we spent less time hand weeding (treatment B compared to A and D).

Costs

Nearly all of our costs were incurred in the first year of the project (2018). The only additional costs from 2019 were for gas to run the mower. We did replace a few plants in transplanted plots in Fall 2019, but we used some extra plants we had purchased in 2018. Below is the total cost of the plants and other supplies for each treatment. Transplanting will always be more expensive than direct seeding.

Treatment Costs
A $417.12
B $539.29
C $18.83
D $390.55
E $3.40
F $149.10
G $23.12

 

You may remember that we were also collecting insects. I promise I will write more about the insects we caught in another post. If you are tired of looking at snow and bare trees outside, you can see pictures of some of the insects we caught in my post from August 2019.

This post was written by Amara Dunn. All pictures were taken by her, unless otherwise credited.

This work is supported by:

  • Crop Protection and Pest Management -Extension Implementation Program Area grant no. 2017-70006-27142/project accession no. 1014000, from the USDA National Institute of Food and Agriculture.
  • New York State Department of Agriculture and Markets
  • Towards Sustainability Foundation

Creating habitat for beneficial insects: How are things growing?

Planting of purple, yellow, and white flowers with blue sky in the background
Lots of flowers bloomed in 2019 in our habitat plots. Some we had planted, and some we hadn’t.

Obviously, nothing is growing right now, but I thought this would be a good time to update you on the success of our beneficial insect habitat plots during the 2019 growing season.

When things bloomed

Recall that the goal is to have at least one plant blooming all season long. We choose wildflower species accordingly, and it worked! The following table shows which months each species bloomed in 2019 (at least in the transplanted plots). An ‘X’ means the species was blooming during that month.

Wildflower May June July Aug Sep
Golden alexanders X X
Catmint X X X  X
Lanced-leaved coreopsis X X
Tall white beard tongue X X
Ohio spiderwort X X
Anise hyssop X X  X
Echinacea X X  X
Orange coneflower X X  X
Boneset X X X
Wild bergamot X X
Common milkweed X
NY ironweed X  X
Showy goldenrod  X
New England aster  X
Blue false indigo

You may notice that the blue false indigo never bloomed in 2019, which was disappointing. Most of these plants are still alive (as you’ll see later in this post). They just didn’t bloom. Maybe next year?

Here’s what each species looks like:

Plant with tiny yellow flowers arranged like Queen Anne’s Lace.
Golden alexanders (Zizia aurea)
Small purple bell-shaped flowers on stems with frosty-green leaves
Catmint (Nepeta faassinii)
Yellow daisy-shaped flowers with toothed edges
Coreopsis (Coreopsis lanceolata)
Clusters of white or pink bell-shaped flowers on top of tall stems
Tall white beard tongue (Penstemon digitalis). Obviously not all of these flowers are white!
Three-petaled purple flowers growing on plant with grass-like leaves.
Ohio spiderwort (Tradescantia ohiensis)
Small, pale purple flowers clustered at the top of a stem
Anise hyssop (Agastache foeniculum)
Pink daisy-shaped flowers with organge centers
Echinacea (Echinacea purpurea)
Large clump of daisy shaped flowers with yellow petals and dark brown centers
Orange coneflower (Rudbeckia fulgida var. fulgida)
Small white flowers in flat clusters
Boneset (Eupatorium perfoliatum)
Pale pink-purple flowers that look like small tufts on the top of stems
Wild bergamot (Monarda fistulosa)
Pale pink flowers with 5 sets of petals and a complex shape
Common milkweed (Asclepias syriaca)
Bright magenta flowers formed into small tufts at the top of the plant
NY Ironweed (Vernonia noveboracensis)
Large clump of small, bright yellow flowers
Showy goldenrod (Solidago speciosa)
Purple daisy-shaped flowers with yellow centers and very narrow petals. A small bee is visiting one of the flowers
New England aster (Symphyotrichum novae-angliae)
Pale blue-purple legume flowers. One is being visited by a bumble bee
Blue false indigo (Baptisia australis); hasn’t bloomed yet in our field. Photo credit: Ansel Oommen, Bugwood.org

Transplanted wildflowers

The wildflowers in our transplanted plots are surviving pretty well (>80%). In the plots that were transplanted in the fall after the buckwheat cover crop, the survival is a bit lower. I think this has to do with some weed control issues (more on this in a future post).

Percent of plants surviving was lowest in treatment D, but still above 80%. Survival did not change very much from Spring to Fall 2019.
How well have the transplanted wildflowers survived so far? Treatment A was transplanted in Spring 2018 and not mulched. Treatment B was transplanted in Spring 2018 and mulched. Treatment D was transplanted in Fall 2018 following a buckwheat cover crop. All have been hand weeded periodically. In both Spring and Fall of 2019 I counted plants to see how well they survived. The black lines on each bar in the graph show one standard error above and below the mean percent survival.

Some species have survived better than others, as the following chart shows. Again, we counted plants both in Spring and Fall 2019.

Bar graph showing the mean percent of plants of each species that were still alive in Spring and Fall 2019. With the exception of milkweed, all survival rates were at or above 80%, and losses were minimal from Spring to Fall.
Do some species of wildflowers survive better when transplanted? There’s a little bit of variability, but overall most are surviving pretty well.

What about the direct-seeded plots?

Only three species of wildflowers planted by seed in Spring or Fall 2018 bloomed during the 2019 season. The table below shows which months these blooms were seen (marked with an ‘X’).

Common name May June July Aug Sep
Coreopsis X X X
Blackeyed susan X X X
Partridge pea X X

Here’s what the flowers of blackeyed susan look like. The plant has much hairier leaves than the orange coneflower.

A daisy-shaped flower with yellow petals and a dark brown center
Blackeyed susan (Rudbeckia hirta)

And here’s the partridge pea:

Yellow flower with compound leaves cupped in a person’s hand
Partridge pea (Chamaecrista fasciculata)

But, I also spotted some wild bergamot, tall white beard tongue, asters, golden alexanders, and either echinacea or orange coneflower seedlings. (I haven’t honed my horticultural skills enough yet to distinguish the foliage of these last two wildflowers.)

Pictures of seedlings labeled (left to right, top to bottom) aster, golden alexanders, echinacea or orange coneflower, wild bergamot, and beard tongue.
Seedlings of some wildflowers could be identified in the direct-seeded plots by September 2019.

There were also plenty of weeds blooming throughout the summer, and many of them were providing pollen and nectar for pollinators and natural enemies. Here are just a few examples:

Four pictures showing a bee on a yellow flower, several daisy-shaped flowers with white petals and yellow centers, a yellow dandelion with a pink lady beetle on it, and a bumble bee visiting a pink clover flower
From left to right: A bee feeding on a weed in the aster family, blooming chamomile, a lady beetle on a dandelion, and a bumble bee visiting clover (that wasn’t planted).

This table summarizes when during the season different weeds were in bloom. Again, an ‘X’ indicates the weed was blooming that month.

Weed May June July Aug Sep
Campion X X X X X
Chamomile X X X X X
Clover X X X X X
Dandelion X X X X X
Vetch X X X X X
Viola X X X X X
Mustard X X X X
Deadnettle X X
Baby blue eyes X
Henbit X
Asters X X X X
Buckwheat X X X X
Oxalis X X X X
Plantain X X X X
Wild lettuce X X X X
Cinquefoil X X X
Indian hemp X X X
Redshank X X X
Chickweed X X
Galinsoga X X
Geraniums X
Sandwort X
Grass X X
Horse weed X X
Lambsquarters X X
Ragweed X X
Black bindweed X
Chicory X

There’s more!

In addition to keeping track of what bloomed from May through September, we were also still tracking costs and time spent on each plot in 2019. And of course we collected a LOT of insects. But those stories will have to wait for another post.

This post was written by Amara Dunn. All pictures were taken by her, unless otherwise credited.

This work is supported by:

  • Crop Protection and Pest Management -Extension Implementation Program Area grant no. 2017-70006-27142/project accession no. 1014000, from the USDA National Institute of Food and Agriculture.
  • New York State Department of Agriculture and Markets
  • Towards Sustainability Foundation

You too can ID aphids…and manage them with biocontrol

Lady beetle on a squash leaf, with a small cluster of pale green aphids nearby.
Caption: Lady beetles will eat any aphid species, but other aphid natural enemies are much more selective. (Photo credit: Amara Dunn)

Practicing good integrated pest management in the greenhouse requires correct identification of the pest. Accurate pest ID is also critical to successful use of biocontrol. Aphids are a good example. Biocontrol of aphids works best when you match the biocontrol agent to the aphid species you have. When I first learned this, I was a bit intimidated, because aphids are pretty small, and I’m not an entomologist. But the four aphid species you are most likely to encounter in your greenhouse are actually pretty easy to differentiate.

Anatomy of an aphid

In order to successfully ID aphids, you need to know (just a little) about aphid anatomy. All aphids are pretty small (between approximately 1/16 and 1/8 inches long). In addition to six legs and a body, aphids have antennae. Antennae attach near their eyes and are angled back over their bodies. They also have two little “spikes” that protrude from their rear end. These are called cornicles. Not so bad, right?

Diagram identifying the antennae on the aphid’s head and the cornicles attached at the rear of the abdomen.
Two features that will help you identify an aphid are the antennae attached to their head, and the two short cornicles attached to the rear end of their abdomen. (Diagram credit: Amara Dunn)

Green peach aphid

Enlarged photo of a light green, green peach aphid with identifying characteristics (indentation between antennae and cornicles that match the color of the body but with dark tips) labeled.
Green peach aphids vary in color from green to pink. Between their antennae you’ll see an indentation, and their cornicles are the same color as their body, with dark tips. (Photo credit: John Sanderson)

Green peach aphids come in different colors (from green to, well, peachy pink) and they are one of the smaller species. Their cornicles are the same color as their body (whatever that color is), and have dark tips on the ends. Green peach aphids also have an indentation in their head between the bases of their antennae.

Melon (or cotton) aphid

Enlarged photo of a dark green melon aphid with the distinguishing dark cornicles labeled.
Melon (also called cotton) aphids can be distinguished from green peach aphids by their dark cornicles. They also lack an indentation between their antennae. (Photo credit: John Sanderson)

Melon aphids (also called cotton aphids) also come in a range of colors that include light yellow, green, dark green, or almost black. Regardless of the body color, the cornicles will always be dark. Also, there’s no indentation in their head between the bases of the antennae. This is another small aphid species.

Foxglove aphid

Enlarged photo of a shiny green foxglove aphid with the distinguishing dark-spotted long antennae, dark leg joints, and darker green spots at the base of the cornicles labeled.
Foxglove aphids are shiny green with long antennae that look like they have dark spots on them. You’ll also see darker green spots at the base of each cornicle and dark leg joints. (Photo credit: Dan Gilrein)

Foxglove aphids are large (for an aphid). Their bodies are light green, but often shiny. There is an indentation in their head between their antennae. Their antennae are extra-long, extending well beyond the end of their body, and appear to have dark spots on them because the joints of the antennae are dark. The joints of their legs are also dark. Check where the cornicles attach to the body of the aphid. Foxglove aphids have darker green spots on their bodies at the base of the cornicles. These aphids usually like to hang out on the lower leaves of a plant, though they will infest flower petals sometimes.

Potato aphid

Enlarged photo of a potato aphid showing the segmented appearance and dark stripe running the length of the body.
Potato aphids have a dark stripe running down the length of their body, and they look faintly segmented. (Photo credit: John Sanderson)

Another large aphid, potato aphids come in pink and green. They look like they have a dark stripe running down the middle of their backs, and their body appears faintly segmented. They also have an indentation in their head between the antennae. Of the four species we’re discussing here, only the melon aphids lack this indentation.

To see these features, you will need a little magnification, but you don’t need a fancy microscope. Find a hand lens or a magnifier with 10X magnification. I like to keep one in my backpack so I’m always prepared.

Picture of a 10X hand lens. The lens folds out from a protective metal cover.
A 10X hand lens will enable you to magnify the features of an aphid that are important for identification.

There are even some relatively inexpensive 10X lenses you can snap on to your smartphone or tablet. Not only does this turn your device into a little microscope, but you can take a picture to document what you see (and show to an expert, later).

Picture of a macro lens that clips on to a smart phone or tablet.
Magnifying macro lenses can be clipped onto your smart phone or tablet, helping you both magnify and document the aphids you find.

You can also find (at least some of) these four aphid species outside. Last summer I spotted the aphid below on an acorn squash plant in August. Now that you know what to look for, what species do you think it might be?

Enlarged photo of a light green aphid with black cornicles. Do you know what species it is?
Use what you’ve learned to identify this aphid! (Photo credit: Amara Dunn)

One minor complication: Each of these four aphid species can either have wings, or be without wings. Usually aphids you find in a greenhouse have no wings, so you can stick with the above descriptions. But winged aphids can appear in the greenhouse, particularly when populations get very high. If you find aphids with wings in your greenhouse, the above descriptions won’t apply; ask for some help from your local extension office.

Enlarged photo of a winged (right) and non-winged (left) green peach aphid. The winged aphid is mostly black and looks very different from the pale green aphid without wings.
Both of the aphids in this picture are green peach aphids, but the one on the right has wings, and would be tricky to identify using the criteria described in this post. Get some help from an expert. (Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org)

Choosing the right natural enemy

Enlarged photo of a tiny parasitoid wasp surrounded by green aphids that appear to be covered in white wax. The wasp is inserting an egg into one of the aphids.
An Aphidius parasitoid wasp lays an egg inside its aphid prey. The developing wasp will kill the aphid. These happen to be cabbage aphids. (Photo credit: David Cappaert, Bugwood.org)

A good biocontrol option for aphids is a parasitoid wasp from the genus Aphidius. These tiny wasps are called parasitoids because they lay their eggs inside of aphids. As the young wasp grows, it kills the aphid and turns it into a mummy.

Enlarged photo of the tan shell of an aphid (mummy) with a hole in it, still sitting on a leaf
Aphids that are eaten from the inside out turn into dry, brown “mummies”. On this aphid mummy you can see the hole from which the adult wasp emerged. (Photo credit: Ken Wise, NYS IPM)

 

But if you want to purchase Aphidius wasps to release in your greenhouse (or the banker plants and prey that support them; read more here), you’ll need to know which Aphidius species to use. Aphidius colemani works well against green peach and melon aphids, while Aphidius ervi works well against foxglove and potato aphids. Another natural enemy you can use is Aphidoletes aphidimyza. This is a tiny fly whose larvae are voracious aphid predators. Although it seems to be less effective against foxglove aphid, it may work well in combination with another natural enemy.

An enlarged picture of what looks like a segmented worm (the larva of Aphidoletes aphidomyza), surrounded by pale green aphids
The larvae of the tiny fly Aphidoletes aphidomyza crawls around on leaves searching for aphids to eat. (Photo credit: Sarah Jandricic)

Like all biocontrols, Aphidius wasps and Aphidoletes larvae need to be released while your aphid population is very small, before it gets out of hand. Aphid infestations can explode very quickly! Scout your crop regularly, and keep records so you know which aphid species you are likely to have. (Consider the Pocket IPM Greenhouse Scout app to help you with your scouting and pest management.) Then plan your biocontrol releases accordingly. Parasitoids and predators for aphids should be released preventatively on crops that are prone to aphids.

If you’ve inspected your aphids at 10X magnification, and still aren’t sure which species you have, contact your local extension office for help with ID. If you are planning to send a picture, make sure that it is clear and shows the features of the aphid that you now know are important (antennae, body, cornicles).

You can learn more about aphid biocontrol in this factsheet from John Sanderson (Department of Entomology, Cornell University) on managing aphids in a greenhouse. Identification of these four common aphid species and which biocontrols you can use against them are also summarized here. The natural enemies listed in the chart are meant to be a starting place. Maximizing the efficacy of your aphid biocontrol program takes some trial and error and willingness to fine-tune your program to the crop and environmental conditions you’re dealing with. Suppliers of aphid natural enemies also have great information about how to use these biocontrol agents most effectively.

Happy aphid hunting!

This post was written by Amara Dunn and Betsy Lamb (NYS IPM) and John Sanderson (Entomology, Cornell University).

Creating habitat for beneficial insects: Starting Year 2

A close-up picture of a lady beetle on a plant
Lady beetle from our beneficial insect habitat plots

Last year I introduced you to the research field at Cornell AgriTech in Geneva, NY where Dr. Betsy Lamb, Brian Eshenaur and I are studying and demonstrating Christmas tree IPM. One part of this project is using perennial wildflowers to attract natural enemies of pests as part of an IPM strategy. The wildflowers (and some perennial grass) species were chosen because of the food and shelter they provide to pollinators. These same resources should make them useful to natural enemies of pests, too.

A plot containing wildflowers (some yellow and purple ones in bloom), with woodchip mulch visible between plants.
Mulching transplants planted in Spring 2018 was the most expensive establishment method, but these plots were looking pretty good a year later, even before we weeded.

By the end of our first field season, we had started using six different methods to establish wildflowers as habitat for beneficial insects (plus a weedy mowed control treatment). We also collected data on how much time and money we spent on establishment and how successful our weed management was. You can read about results from Year 1 in my post from last November.

But beneficial insect habitat establishment is not a one-year project. The establishment methods we started to implement in 2018 are ongoing, including periodic mowing of direct seeded plots, and hand-weeding of transplanted plots. We’ll keep track of how much time and money we invest in these plots in 2019, too.

The same plot is shown in two pictures. The picture on the left has some bare ground visible and many patches of grass and broadleaf weeds. The picture on the right shows the plot after it was mowed.
Plots that were direct seeded in 2018 will be mowed this year to favor the perennial beneficial insect habitat plants over annual weeds. This plot was treated with alternating herbicide and tillage during Summer 2018, and wildflower seed was planted in Fall 2018; (A, left) plot before mowing, (B, right) same plot after mowing.
Two pictures of the same plot before (left) and after (right) weeding. The un-weeded plot has lots of dandelion seed heads and no bare ground is visible. After weeding, you can see some bare ground and it’s easier to see the wildflower plants.
Plots that were transplanted in 2018 will be hand weeded this year to help the perennial wildflowers and grasses out-compete weeds. This plot was transplanted in Spring 2018 into bare (not tilled) ground and no mulch was used; (A, left) plot before weeding, (B, right) same plot after weeding.

And we want to know whether these plots are actually attracting beneficial or pest insects. So, in 2019 we are starting “Phase II” of our beneficial insect habitat work. We want to know which and how many insects (and other arthropods, like spiders) are being attracted to each type of plot. We will also count insects in no habitat plots (weedy, mowed occasionally) and mowed grass plots in the middle of the Christmas tree field for comparison.

Insect collection began in early May, and we are using four different techniques:

  • Sweep net – This is what it sounds like. We “sweep” a net through the air above the ground to capture mostly flying insects, or those who may be resting on the plants.
  • Butterfly and moth count – We walk through the field, counting how many of each butterfly or moth species we see in each plot.
  • Pan traps – These are bright yellow and blue bowls filled with soapy water. One bowl of each color is placed in each plot for 2 days, then we collect the insects that have been attracted to the colorful bowls and were trapped in the soapy water. This method will help us count flying insects, especially bees and wasps.

    A bright blue plastic bowl and a bright yellow plastic bowl are filled with soapy water and small rocks. Both are set on bare ground with some plants growing nearby.
    Bright blue and yellow bowls filled with soapy water and weighed down with rocks will attract certain flying insects. By counting insects collected in these pan traps, we can learn which insects are spending time in each plot.
  • Pitfall traps – These are clear plastic 16-oz deli cups (like you might use for take-out food) that are sunk into the ground in each plot. Insects that crawl along the ground fall in. We will use this method to count mostly ground-dwelling insects.

    A 16-ounce plastic deli cup sunk in bare soil of a plot so that the rim is level with the ground. The cup is half-full of liquid and also has caught a few green beetles. The trap is covered by a clear plastic dinner plate held about 6 inches above the ground by wire legs.
    A pitfall trap collects ground-dwelling insects. This one is protected by a rain cover. We didn’t want all the rain we’ve been getting this spring to overflow the traps and wash away the insects we caught!

I will write another blog post or two about this project during or at the end of this season. If you want to see more frequent updates, follow me on Twitter (@AmaraDunn). I’ll post weekly pictures of this project, including which beneficial insect habitat plants are blooming each week. You can also see lots of pictures from this project on Instagram (biocontrol.nysipm).

This work is supported by:

  • Crop Protection and Pest Management -Extension Implementation Program Area grant no. 2017-70006-27142/project accession no. 1014000, from the USDA National Institute of Food and Agriculture.
  • New York State Department of Agriculture and Markets
  • Towards Sustainability Foundation

And the results are in…from Year 1. What do biofungicides add to vegetable disease management Part 3

Cucurbit powdery mildew on a winter squash leaf.
One of our goals for this project was to understand what biofungicides might add to a cucurbit powdery mildew management program.

Introduction

In 2018 we conducted field trials using biofungicides in cucurbit powdery mildew and snap bean white mold management programs. Hopefully you’ve read part 1 and part 2 of this biofungicide story. If not, now might be a good time.

Part 1 will give you more details about the trial design. We wanted to know whether adding biofungicides would improve disease control, plant health, or yield. For cucurbit powdery mildew, we were adding one of three different biofungicides to a conventional chemical spray program. We also included a treatment that was all OMRI-listed (organic) products. For white mold on snap beans, we were curious about using an in-season biofungicide (Double Nickel, Bacillus amyloliquefaciens strain D747) in combination with a pre-season biofungicide (Contans, Paraconiothyrium minitans strain CON/M/91-08). In 2018, our white mold treatments were just Double Nickel and Cueva (an OMRI-listed copper). In 2019, we’ll add the pre-season Contans treatment.

Part 2 explains more about the modes of action of the five biofungicides we are looking at. The post also includes practical information about how to use these biofungicides to maximize their efficacy – compatibility with other products, best way to store them, when to apply them, etc.

Now it’s time to talk about what we learned from this first year (of a two-year project).

The bottom line

We don’t want to keep you in suspense, so here’s a quick summary of what we learned. Fortunately for the eastern NY grower who graciously allowed us to run the trial on his farm (but unfortunately for us), the snap bean field had very little white mold in 2018. Even the plots that were not sprayed with Double Nickel or Cueva had almost no disease. So we weren’t surprised when there were no differences in disease, plant health, or yield among the white mold treatments. Results from Sarah Pethybridge’s efficacy trials with OMRI-approved products for white mold are available online.

A healthy field of snap bean plants.
Our snap bean trial in eastern NY in 2018 had very little white mold. (Photo credit: Crystal Stewart)

Cucurbit powdery mildew was a bit more severe than white mold (low pressure in eastern NY, moderate pressure in western NY and on Long Island), but we were not able to detect statistically significant benefits from adding biofungicides to a conventional spray program. Disease severity, plant health (as measured by NDVI), yield, and fruit quality (Brix) were the same whether you used a conventional spray program, or a conventional spray program plus a biofungicide. We didn’t measure significant differences in yield among any of the treatments at any of the three sites.

The conventional powdery mildew spray program alone, or when combined with LifeGard, Regalia, or Serifel significantly reduced disease compared to no treatment for cucurbit powdery mildew. Adding any of the biofungicides to the conventional spray program did not improve control compared to using only the conventional sprays. The organic (OMRI-listed products) treatment was not significantly different from either no sprays at all, or the conventional spray program.
Severity of powdery mildew on the upper sides of the leaves in the Western NY trial. Here, disease severity is quantified using the area under the disease progress curve (AUDPC). This number summarizes disease severity from multiple dates, and the larger the number, the worse the disease. If two treatments share the same letter, the average disease in those treatments is not significantly different. The error bars give you an idea of how much variability there was in each treatment.

NDVI results

NDVI (normalized difference vegetation index) values did not detect cucurbit powdery mildew early. (Since there was so little white mold, we couldn’t test NDVI for early detection.) There was some inconsistent correlation between NDVI readings and disease, yield, and Brix in winter squash. In WNY we used both a handheld GreenSeeker and a gator-mounted Crop Circle to measure NDVI. Both devices had similar results. Based on this first year of testing with these two devices, NDVI measurements were not useful as an early indicator of cucurbit powdery mildew.

In addition,  NDVI measurements did not  detect subtle differences in plant health among treatments. At only one of our three sites (Long Island) were there any significant differences in NDVI among treatments. This was only on the last two rating dates in the season, when powdery mildew was visibly more severe in the non-treated control than the conventional fungicide treatments.

On the last two rating dates of the season (August 31 and September 17), NDVI values were significantly higher in the conventional powdery mildew spray program treatment and all three of the conventional + biofungicide treatments, compared to the plots that were not treated for powdery mildew. Adding the biofungicides did not significantly improve NDVI, compared to using only conventional products.
Normalized difference vegetation index (NDVI) measured on winter squash in the Long Island trial on three dates at the end of the season. NDVI values closer to 1 indicate more healthy, green foliage. If two treatments have the same a letter on the same date, the average NDVI readings on that date were not different between the two treatments. Data from August 31 are labeled with uppercase, while data from September 17 are labeled with lowercase letters. There were no differences among any treatments on August 24. The error bars give you an idea of how much variability there was in each treatment. We couldn’t do statistics on the organic treatment because too many plants were killed by Phytophthora blight in the plots that received this treatment.

Some caveats

The non-treated control (received no powdery mildew fungicide) was often not significantly different from the conventional fungicide control (our best management program). We know that controlling powdery mildew on cucurbits is important, so if we don’t detect a significant difference between the non-treated control and the treatment that should have provided the best control, it is then hard to draw further conclusions from the data.

We didn’t measure statistically significant differences in marketable yield among any of the treatments at any of the sites. Data for eastern NY are shown in this graph.
We didn’t detect statistically significant differences in marketable yield among any of the treatments in any of the trials. Here are the data from eastern NY. Notice that all six bars are labeled with the letter “a”. As with previous graphs, the error bars give you an idea of how much variability there was across the different plots in each treatment.

When disease pressure is low (as it was in Eastern NY), we would expect not to see many differences between treatments. Similarly, if the conventional fungicide program provided excellent disease control (as it did on Long Island), it would be hard to detect an improvement in control from adding a biofungicide. Another challenge we dealt with in the Long Island trial was Phytophthora blight. By the end of the season, we had lost two of the four plots receiving the organic treatment to this disease. This limited our ability to statistically analyze the biofungicide data. On Long Island, the organic spray program initially performed well – as seen on August 31  – comparable to the conventional treatments. But by the final assessment on September 17, the organic program was no longer as effective. This was not surprising since it was 10 days after the last application. Suffoil-X was the final organic product applied, and it has little residual activity.

In the Long Island trial, there was very little disease on August 16 or 24. On August 31, disease had increased in the non-treated control, but the organic treatment was still suppressing disease well. Control in the organic treatment had declined by September 17, but this was 10 days after the last spray was applied.
Average severity of powdery mildew on the upper surface of leaves on the last four assessment dates in the 2018 Long Island trial. All of the treatments (except the non-treated control) suppressed powdery mildew well through August 31. Control in the organic treatment had declined by September 17, but this was 10 days after the last spray was applied.

In WNY, we had an epic aphid outbreak. An entomologist colleague identified them as probably melon aphids, and also that 2018 was generally a bad year for aphids. It’s also possible that while trying to control cucumber beetles earlier in the season, we killed some aphid natural enemies, contributing to an aphid outbreak later in the season. I know cucumber beetles are tough, but if you can manage them without decimating your local natural enemies, you’ll be doing yourself a favor!

The underside of a squash leaf covered with aphids; an acorn squash fruit covered with shiny honeydew from aphids; a close-up picture of an adult aphid and some young aphids.
The severe aphid outbreak in the western NY trial may have made it more difficult to detect differences among treatments. In late August, some of the leaves were covered with aphids (A), and many fruit were covered with honeydew (B). Getting a close look at the aphids is essential for correct identification (C).

We deliberately used a very intensive spray program, starting our biofungicide applications early, and continuing to apply them as we added conventional fungicides later in the season. This was an expensive powdery mildew management program. But, in this first year of the project, we didn’t want to be left wondering if a lack of differences was due to underapplication of the biofungicides.

If you want to see more of the data we collected from the cucurbit powdery mildew trial, you can find it in the Proceedings from the 2019 Empire State Producers Expo.

What does this all mean?

First, this is only the first year of our project and one year of data. It’s a start, but we’ll hopefully learn more in a second year. Since we didn’t measure a significant improvement in yield, we didn’t see evidence that adding biofungicides to a full chemical spray program for powdery mildew justified the cost. The relative costs of the treatments we used are listed in the table below, and the approximate per acre costs of each product are in the Proceedings from the 2019 Empire State Producers Expo. Replacing a chemical spray or two with a biofungicide could be a more economical option. That’s something we’re planning to look at in 2019.

Treatment
Date Non-treated Conventional Conventional + LifeGard Conventional + Regalia Conventional + Serifel Organic
7/19/18 LifeGard Regalia Serifel LifeGard
7/27/18 LifeGard Regalia Serifel LifeGard
8/3/18 Vivando LifeGard + Vivando Regalia + Vivando Serifel + Vivando MilStop
8/10/18 Quintec LifeGard + Quintec Regalia + Quintec Serifel + Quintec Serifel
8/17/18 Luna Experience LifeGard + Luna Regalia + Luna Serifel + Luna SuffoilX
8/24/18 Vivando LifeGard + Vivando Regalia + Vivando Serifel + Vivando MilStop
8/31/18 Quintec LifeGard + Quintec Regalia + Quintec Serifel + Quintec Serifel
9/7/18 Luna Experience LifeGard + Luna Regalia + Luna Serifel + Luna SuffoilX
Total cost (per A) $228.28 $343.32 $536.28 $696.28 $257.76
Cost increase vs. conventional (per A) $  – $115.04 $308.00 $468.00 $29.48

Based on results from this year, we can’t yet recommend that you run out and buy a handheld NDVI sensor for early detection of cucurbit powdery mildew. We’ll collect NDVI data again in 2019, and let you know what we learn. Although our results from the field trials were somewhat inconclusive in this first year, we’re hopeful that the information we’ve compiled about how these biofungicides work and how to use them will be useful. If you’re thinking of using Contans, Double Nickel, LifeGard, Regalia, or Serifel in 2019, first take a look at these fact sheets related to our white mold and powdery mildew trials. And if you have used biofungicides, we’d be interested in hearing about it; click here to send an e-mail.

This post was written by Amara Dunn (NYS IPM), Elizabeth Buck (Cornell Vegetable Program), Meg McGrath and Sarah Pethybridge (both Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University), Crystal Stewart (Eastern NY Commercial Horticulture Program), and Darcy Telenko (Department of Botany & Plant Pathology, Purdue University). Thank you to the New York Farm Viability Institute for funding.

How do they work? Bioinsecticide edition

When an insect is treated with the right bioinsecticide, the insect stops damaging plants, and eventually dies.
Bioinsecticides include microorganisms and other naturally-derived compounds that control insect pests.

My post from last February described modes of action for biopesticides that target plant diseases…as well as the difference between a biopesticide and a biostimulant. January’s post described the modes of action of five biofungicides in an ongoing vegetable trial. But there are plenty of insect and mite pests out there, too. You can attract or release predatory or parasitic insects and mites or beneficial nematodes to deal with these arthropod (insect and mite) pests. But you can also use bioinsecticides that control insects and mites. The active ingredients include microorganisms (bacteria, fungi, viruses), plant extracts, or other naturally-occurring substances. Want to know how they work? Keep reading.

Bioinsecticides can have one (or more) of the following modes of action:

  1. Kill on contact
  2. Kill after ingestion
  3. Repel
  4. Inhibit feeding
  5. Inhibit growth
  6. Inhibit reproduction

The examples included in the following descriptions are reported either on the bioinsecticide labels or in promotional materials produced by the manufacturers. And these are just examples, not meant to be an exhaustive list of bioinsecticides with each mode of action.

Killing on contact

Tiny spores of insect-killing fungi land on the body of an insect, germinate, infect the insect, grow throughout its body, and eventually kill it.
Some bioinsecticides contain living spores of a fungus. These spores need to land on the insect. Then they germinate (like a seed), invade and grow throughout the body of the insect, and eventually kill it. If the humidity is high enough, the fungus may even produce more spores on the body of the dead insect.

Some bioinsecticides need to directly contact the body of the insect or mite in order to kill it. Bioinsecticides that contain living fungi work this way. The tiny fungal spores land on the insect or mite pest, germinate (like a seed), and infect the body of the pest. The fungus grows throughout the pest’s body, eventually killing it. If the relative humidity is high enough, you might even see insects that look like they are covered with powder or fuzz (but this is not necessary for the pest to die). This powdery or fuzzy stuff growing on the pest is the fungus producing more spores. Bioinsecticides that contain the fungal species Beauveria bassiana (e.g., BotaniGard, Mycotrol), Metarhizium anisopliae or brunneum (e.g., Met52), or Isaria fumosorosea (NoFly) are examples of fungal bioinsecticides with contact activity.

An insect covered in the white powdery fungus that has started growing out of its body following infection.
If the relative humidity is high enough, insects infected with a fungus may start growing new fungus on the outside of their bodies, appearing fuzzy or like they are covered in powder. Photo credit: Louis Tedders, USDA ARS, Bugwood.org

Bioinsecticides that contain spinosad (including Entrust, SpinTor, and others) work because the active ingredient affects the nervous and muscular systems of the insect or mite, paralyzing and eventually killing it. It can kill the pest either through contact, or through ingestion (more on that in a moment). The bioinsecticide Venerate contains dead Burkholderia bacteria (strain A396) and compounds produced while growing the bacteria. One mode of action of Venerate is that it contains enzymes that degrade the exoskeleton (outer shell) of insects and mites on contact.

Killing by ingestion

Some bioinsecticides need to be eaten (ingested) in order to kill. Pesticides that contain the bacteria Bacillus thuringiensis (often called Bt for short) as the active ingredient are a good example. Proteins that were made by Bt while the bioinsecticide was being manufactured are eaten by insects and destroy their digestive systems. Several different subspecies of Bt are available as bioinsecticides, and the subspecies determines which insect pest it will be effective against. There are many bioinsecticides registered in NY that contain Bt as an active ingredient. Check NYSPAD for labels, and make sure you choose the right pesticide for the pest and setting where you need control. Bt products do not work on mites, aphids, or whiteflies.

A caterpillar eats a bioinsecticides that kills by ingestion. Later, the caterpillar dies.
Some bioinsecticides (blue diamonds in this diagram) will only kill pests if they are eaten first. Pesticides that contain Bacillus thuringiensis (Bt) bacteria or insect viruses are examples of this mode of action.

Insect viruses are another example of a bioinsecticide active ingredient that kills through ingestion. For example, Gemstar contains parts of a virus that infects corn earworms and tobacco budworms. Once these caterpillars eat the Gemstar, the virus replicates inside the pest, eventually killing it.

Repel

Some bioinsecticides repel insects from the plants you want to protect. However, this mode of action may only work on certain pest species, or certain life stages of the pest. Read and follow the label. Bioinsecticides containing azadirachtin or neem oil, and Grandevo are reported to have repellent activity for some pests. Grandevo contains dead bacteria (Chromobacterium substugae strain PrAA4-1) and compounds produced by the bacteria while they were alive and growing.

One leaf has been treated with a bioinsecticides that repels pests, but one leaf has not. The caterpillars are feeding on the leaf that was not treated.
Some bioinsecticides (blue diamonds and happy microbes in this diagram) protect plants because they repel insect and mite pests. This protects treated plants from pest damage.

Inhibit feeding

If you want insect and mite pests dead as soon as possible, I understand the sentiment. But in many cases stopping the pests from eating your plants would be just as good, right? Some bioinsecticides cause pests to lose their appetite days before they actually die. Like bioinsecticides that kill pests outright, some bioinsecticides that inhibit feeding require ingestion, while others work on contact. And these bioinsecticides may work this way for only certain pest species of certain ages. Read and follow those labels! Bioinsecticides containing Bt require ingestion and some can stop pest feeding before actually killing the pest. The same goes for Gemstar (corn earworm virus). This is another mode of action of azadirachtin products against some pests.

A caterpillar eats or comes in contact with a bioinsecticide that causes the caterpillar to stop feeding.
Some bioinsecticides (blue diamonds and happy microbes in this diagram) cause insect and mite pests to lose their appetites. Depending on the bioinsecticide, it either needs to contact the pest or be eaten by it.

Inhibit growth

Many insects and mites need to molt (shed their skin as they go from one life stage to another). Bioinsecticides that interfere with molting prevent pests from completing their life cycle. Like feeding inhibitors, these bioinsecticides won’t directly kill the pests you have, but they can prevent them from multiplying. This is another mode of action (again, for certain pests at certain stages of development) listed for azadirachtin products and Venerate (Burkholderia spp. strain A396).

Some aphids were treated with a bioinsecticides that inhibits growth. They stay the same size. Another aphid that was not treated grows and molts normally.
Some bioinsecticides (blue diamonds in this diagram) don’t kill insects and mites outright, but they can prevent them from molting and growing into the next life stage. Pests that can’t move on to the next life stage will eventually die without completing their life cycle.

Inhibit reproduction

There are two main types of bioinsecticides that prevent or slow insect reproduction. Pheromones are compounds that confuse insects that are looking for mates. If males and females can’t find each other, there won’t be a next generation of the pest. Pheromones can be especially useful when the adults that are looking for mates don’t feed (e.g., moths). Isomate and Checkmate are two examples of pheromones available for certain fruit pests. Other bioinsecticides actually reduce the number of offspring produced by a pest. This is one of the modes of action of Grandevo (Chromobacterium substugae strain PRAA4-1) against certain pests.

Male and female moths are unable to find each other and mate because of the presence of pheromones nearby.
Pheromones (represented here by blue diamonds) are a type of bioinsecticide that confuses insects looking for a mate. As a result, males and females can’t find each other, don’t mate, and don’t lay eggs.

Why do I care?

Do you mean besides the fact that you are a curious person and you want to know how biopesticides work? Knowing the mode of action for the pesticide you use (among other things) allows you to maximize its efficacy. Does the bioinsecticide need to contact the pest, or be eaten by it? This determines where, when, and how you apply it. Do you want to use a bioinsecticide that inhibits growth of the pest? Make sure you use it when pests are young. (Sidenote: Like all biopesticides, bioinsecticides generally work best on smaller populations of younger pests.) Is the first generation of the pest the one that causes the most damage? Don’t rely on a bioinsecticide that inhibits reproduction. Although if the pest overwinters in your field and doesn’t migrate in, maybe you could reduce the population for the next season.

Now is a great time of year to consider the insect and mite pests you are likely to encounter this season, then learn which bioinsecticides include these pests (and your crop and setting) on the label. Always read and follow the label of any pesticide (bio or not). How do you know whether these bioinsecticides are likely to work in NY on the pests listed on the label? That’s a topic for another post. In the meantime, the Organic Production Guides for fruit and vegetables from NYS IPM are a great place to start. When available, they report efficacy of OMRI-listed insecticides (including some bioinsecticides). Your local extension staff are another great resource.

How do they work? How do I use them? What do biofungicides add to vegetable disease management Part 2

rows of healthy winter squash plants with flags
Winter squash in our cucurbit powdery mildew biopesticide trial conducted in western NY, eastern NY, and on Long Island in 2018. We are also testing biopesticides for white mold. Photo credit: Meg McGrath.

Remember from Part 1 of this post that we (I and many great colleagues) are studying what biopesticides can add to effective disease management of cucurbit powdery mildew and white mold. After “what is a biopesticide?” the next most common questions about this project are about the specific biopesticides we’re testing:

  • How do they work?
  • Can I tank mix them with other pesticides or with fertilizers?
  • Do I need to use these products differently than I would use a chemical pesticide?

Today’s post will try to answer those questions.

 

Modes of action – How do they work?

As you may recall from February’s post, biopesticides work in different ways, and the five biofungicides we’re studying cover the range of these modes of action.

table summarizing modes of action for Contans, Double Nickel, LifeGard, Regalia, and Serifel
Biopesticides protect plants from diseases in different ways. I like to divide them up into the five modes of action (MOAs) in this table. Like many biopesticides, some of the products we are testing have more than one MOA. Click on the table to enlarge it.

Eats pathogen

The fungus active ingredient of Contans (Paraconiothyrium minitans strain CON/M/91-08; formerly called Coniothyrium minitans) “eats” (parasitizes and degrades) the tough sclerotia of the fungus, Sclerotinia sclerotiorum that causes white mold. Sclerotia survive in the soil from year to year. However, for this strategy to be effective, the fungal spores within Contans have to first make contact with the sclerotia. The time between colonization and degradation of sclerotia is about 90 days.

Makes antimicrobial compounds

The active ingredients in Serifel and Double Nickel are bacteria – same species but different strains. They both produce compounds that are harmful to plant pathogens (antimicrobial). According to the manufacturer, most of the foliar efficacy of Double Nickel is due to the antimicrobial compounds already present in the container. But the manufacturer notes that some of the efficacy also comes from the live bacteria that are responsible for this product’s other modes of action, especially the induction of plant resistance (more on this later). The strain of bacteria in Serifel has been formulated so that it contains only living bacteria (no antimicrobial compounds). The manufacturer’s goal is for the bacteria to produce antimicrobial products unique to the specific environmental conditions after application. Double Nickel and Serifel are examples of different strategies for using antimicrobial-producing bacteria to fight plant diseases. Our goal is to explain how the products work; not tell you which strategy is better.

smiling blue bacteria on a leaf; angry yellow bacteria have no place to land
Some biopesticides contain microbes that grow on the plant. These beneficial microbes use up space and nutrients so there is no room for the pathogen, excluding it.

Excludes pathogen

The bacteria in Double Nickel and Serifel also can protect plants from disease by growing over (colonizing) the plant so that there is no space or nutrients available for pathogens. How important this mode of action is to the efficacy of Double Nickel depends on the setting and time of year (according to the manufacturer). Cucurbit leaves exposed to sun, heat, and dry air are not great places for bacteria to grow, and pathogen exclusion is not likely to be very important in protecting cucurbit leaves from powdery mildew. The antimicrobial MOA is more important here. Apple blossoms being protected from fire blight in the early spring could be a different story. The bacteria in Serifel tolerate a wide range of temperatures in the field, but the manufacturer recommends applying this product with a silicon surfactant to help the bacteria spread across the plant surface better.

Induces plant resistance

Plants have mechanisms to defend themselves. Some pathogens succeed in causing disease when they avoid triggering these defenses, or when they infect the plant before it has a chance to activate these defenses. Some biofungicides work by triggering plants to “turn on” their defense mechanisms. This is called “inducing plant resistance.” It is the sole mode of action of the bacteria in LifeGard, and one of the modes of action for the active ingredients in Double Nickel, Regalia, and Serifel.

Promotes plant growth and/or stress tolerance

The last biofungicide being studied in this trial has a plant extract as an active ingredient, instead of a microorganism. Regalia works by both inducing plant resistance, and also promoting plant growth and stress tolerance. Some of the other products in this trial also share these MOAs. According to the label, some crops treated with Regalia produce more chlorophyll or contain more soluble protein. This final MOA (promotion of plant growth and stress tolerance) is also sometimes shared with “biostimulants”. But remember that “biostimulant” is not currently a term regulated by the EPA. This may be changing in the future, so stay tuned. Biostimulants enhance plant health and quality. They are not registered as pesticides, and must not be applied for the purpose of controlling disease. Make sure you read and follow the label of any product you apply.

Best practices – How do I use them?

We’ll get to some product-specific details in a minute, but first some notes about best uses for all five of these products.

  • They need to be used preventatively. For biofungicides to eat pathogens, exclude them from plants, induce plant resistance, or improve plant growth and stress tolerance, they need to beat the pathogen to the plant. It takes time for the plant to fully activate its defenses, even if “flipping the switch” to turn those defenses on happens quickly. The same applies to promoting plant growth and stress tolerance. And if you want the beneficial microorganism to already be growing where the pathogen might land, of course you need to apply the product before the pathogen is present. Microbes that produce antimicrobial compounds also work best if they are applied when disease levels are low.
  • Use IPM. These biofungicides (and most, if not all, biofungicides) were designed to be used with other pest management strategies like good cultural practices, host resistance, and other pesticides. For example, they can be included in a conventional spray program to manage pesticide resistance.
  • Mix what you need, when you need it. Don’t mix biofungicides and then leave them in the spray tank overnight. Some products may need to be used even more promptly. Check the label.
  • Store carefully. Generally, away from direct sunlight and high heat. Follow the storage instructions on the label.
  • They have short intervals, but still require PPE. One of the benefits of biofungicides is short pre-harvest intervals (PHIs) and re-entry intervals (REIs). All five of the products we’re studying have a 0 day PHI and a 4 hour REI. But they all still require personal protective equipment (PPE) when handling and applying them. Read and follow those labels!
  • Tank mixing best practices still apply. The table at the end of this post has details about biological compatibility of these products in tank mixes, as reported by the manufacturers. But just like other pesticides, you need to follow the label instructions for mixing. If you have questions about a specific tank mix partner, confirm compatibility with a company rep. Do a “jar test” if you are mixing two products for the first time and want to know if they are physically compatible.

Biopesticides (especially those that contain living microorganisms) often need to be handled and used differently than chemical pesticides. They may be more sensitive to temperature, moisture, or UV light, which may impact the best time or place to apply them. And of course you don’t want to tank mix a living microorganism with something that will kill the good microbe. (Cleaning your tank well between sprays is always recommended, whether or not you are using a biopesticide.) The following table summarizes details for the five products we’re studying provided by the manufacturers – from product labels, company websites, and conversations with company reps. We have not personally tested this information.

summary of FRAC codes, where and when to apply, temperature tolerance in the field, rainfastness, UV tolerance, tank mix compatibility, storage and shelf life for 5 biopesticides
Exactly how should you use these biofungicides to maximize their efficacy? This table summarizes best practices (as reported by the manufacturers) for each of the five fungicides tested in this trial. Click on the table to enlarge it.

We’ve created handouts that summarize the designs of both the cucurbit powdery mildew and the white mold trials, the modes of action of the five biofungicides we’re testing, and the best practices information presented above.

cucurbit powdery mildew biofungicide trial summary

white mold biofungicide trial summary

Stay tuned for Part 3 of this post – results from our first year of field trials!

 

This post was written by Amara Dunn (NYS IPM) and Sarah Pethybridge (Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University). Thank you to the New York Farm Viability Institute for funding.

A new resource to help you protect pollinators

honey bee is perched on top of a young developing squash with the flower still attached
Many crops (and plenty of non-crop plants) rely on pollinators. Let’s protect them!

As I’ve discussed before, the natural enemies that provide biological control of pests include both larger creatures (like insects, mites, and nematodes) and microorganisms (fungi, bacteria, and viruses) that combat pests in a variety of ways. Microorganism natural enemies are regulated as pesticides (one type of biopesticide), while the larger natural enemies are not. Growers who are successfully using biocontrol insects, mites, and nematodes usually recognize that they need to apply pesticides in such a way that they are compatible with the biocontrol organisms they use. Take a look at my April post for a summary of online resources that can help you check compatibility of pesticides (including biopesticides) with natural enemies.

Some of these compatibility resources include information on the effects of pesticides (and biopesticides) on bees. Pollinators (including honey bees, lots of other bees, and some non-bees) are very important beneficial insects. You may have noticed that they have found their way into several of my blog posts. So, I wanted to let you know about a brand new resource (hot off the digital presses) to help you protect pollinators.

Image of the cover of the resouces entitled: Pesticide decision-making guide to protect pollinators in tree fruit orchards
“A Pesticide Decision-Making Guide to Protect Pollinators in Tree Fruit Orchards” is a terrific resource to help you choose pesticides (and pesticide combinations) that are least-toxic to bees.

A Pesticide Decision-Making Guide to Protect Pollinators in Tree Fruit Orchards” was written by Maria van Dyke, Emma Mullen, Dan Wixted, and Scott McArt. Although it’s focus is tree fruit orchards (and therefore the pesticides used in them), it should be useful for growers of other crops who want to choose pesticides that are least toxic to bees. A few highlights:

  • It includes information not only on pesticides used alone, but (when available) on synergistic effects when multiple pesticide active ingredients are used together. When you combine some chemicals (either in the tank or in the environment) the mixture is more toxic than both chemicals alone.
  • Where available, it summarizes pesticide toxicity to other bees besides just honey bees (e.g., bumble bees and solitary bees). You can read more about why this is important in this recent article.
  • It describes what we know about sub-lethal (in other words, negative effects on the bees that are less serious than death) effects of pesticides on bees.
  • It includes about half a dozen biopesticide active ingredients.
bumble bee feeding on a purple flower
Pollination is being done by more than just honey bees! This bumble bee (plus many more bee species) are important pollinators in NY.

Guides for other crops and other resources for growers wanting to protect pollinators can be found here.

You might be asking: If a chemical on this table is toxic to bees, will it also be toxic to the insect and mite natural enemies I am releasing or conserving on my farm or in my garden? I wish I had a definitive answer to that. As you can see from the nearly three pages of Literature Cited at the end of this document, collecting these data is a time-consuming process. For now, stick with the compatibility resources that are already available, and ask the companies you buy from (pesticides or natural enemies) about compatibility.

In closing, a huge amount of work went into this resource to summarize so much useful and current (as of October 2018) information in an easy-to-read table. Bravo to the authors! The Pollinator Network @ Cornell has other helpful resources for growers on protecting pollinators. Winter is a great time to make plans for using IPM and protecting the pollinators and natural enemies that are so good for the crops we grow!