With all the Japanese beetles I’ve been pulling off my zinnias, it was a pleasant surprise to find a more friendly beetle!
It’s been two months since I since I wrote about the plants I selected to provide habitat for beneficial insects around my home. Today I’ll talk a bit about weed control and how my spring transplants are doing.
Weed control
I have mentioned before that managing weeds turns out to be far more than half the battle when it comes to establishing perennial wildflowers as habitat for beneficial insects. Based on the results from the habitat plots we planted on the edges of our Christmas tree research field, I decided to use mulch for weed management in my home gardens. While mulch does add extra cost, after you make the initial investment of time to spread the mulch, it really cuts down on the time required to manage weeds during the rest of the season. I had a relatively small area to mulch, and was able to purchase some relatively inexpensive mulch made from the brush and leaves picked up by my city. Also, while I haven’t tested the organic matter content of my soil, just digging up some of the grass told me that my soil could use more organic matter. The mulch will eventually help with that as it breaks down. One downside to mulch is that it could block access to the soil for ground-nesting bees. There are some spots of bare ground in other parts of my yard, and perhaps next year I will be a little more deliberate about keeping some areas bare to support these pollinators.
I decided to use mulch for weed control in my home beneficial insect habitat.
Like many (but not all) New Yorkers, I have found myself frequently wishing for more rain this summer. According to the closest NEWA station, we only got 1.3 inches of rain in May, 1.44 inches in June, and 1.48 inches in July (so far). This spring and summer is an excellent illustration of why experts recommend transplanting perennials in the fall, and not in the spring. Hot and dry are not ideal conditions for young seedlings just trying to get started. We often get more rain in the fall, and the cooler temperatures mean the transplants are subjected to less stress.
I started my plants from seed, and most of my seedlings were pretty small when I transplanted them the first week of June.
This picture was actually taken about 2 weeks after I transplanted my seedlings. They were a little on the small side.
I admit that I also didn’t harden off my seedlings exactly the way you are supposed to. After losing some un-protected plants to marauding bands of squirrels, and lacking a protective structure that would let me keep my seedlings in full sun, I hardened them off on my screen porch. Moving from this environment to the south side of my house in full sun was a bit of a shock, especially when it got so hot and dry so soon after transplanting. I’ve done a lot of watering over the past month and a half, and I still lost more of my perennial seedlings (and some annuals) than I had hoped.
There were supposed to be three echinacea plants in this picture. At least one of them survived!
In spite of these obstacles, quite a few of my transplants survived. The blanketflowers (Gaillardia aristata) are the only perennials that look like they will bloom this season. If I had bought seedlings from a local nursery, they might have been bigger and might have established faster. But I can be patient.
I think I can see the beginnings of a flower bud on this blanketflower.
You already saw the echinacea. Here are some of the other perennials.
Some of the surviving rudbeckia (left) and pyrethrum daisy (right) seedlings.
Not surprisingly, the annuals have grown faster. (Remember, they’re in a race to reproduce and pass on their genes before winter returns!)
Japanese beetles are eating the common zinnias.
A small consolation is that the Japanese beetles seem to like my roses even more than they like the zinnias. The roses are functioning as a sort of trap crop.
But they are leaving the ‘Persian Carpet’ zinnias alone. It turns out these are a variety of Mexican zinnias (Zinnia haageana), which is a different species than the common zinnias (Zinnia elegans).
‘Persian Carpet’ zinnias have smaller flowers, smaller leaves, and no Japanese beetle damage, even though I planted them right next to my roses.
I’ve been picking the Japanese beetles off by hand (adding them to my compost bin after they drown). I found the beetles to be more sluggish in the evenings (although admittedly I wasn’t out at the break of dawn), and a colleague recently shared this article with me that suggests that hand-picking Japanese beetles in the evening is indeed the best option. This strategy has not prevented all damage (especially on my roses), but I think my plants will survive. And I admit I haven’t picked them every single day.
Japanese beetles picked off of my plants and drowned
The snap dragons have started blooming.
I planted snap dragons mostly because I like them as cut flowers, although I have seen reports that they support bees.
And so have the calendulas.
Calendula in bloom.
I’ve seen hover flies on the bachelor’s buttons. Remember the adult hover flies are pollinators, while their larvae are voracious aphid predators.
I’ve seen a few hover flies visiting the bachelor’s buttons.
The cosmos and sunflowers (that survived the squirrels and a local rabbit) haven’t started blooming yet, but they’re looking good!
The squirrels must not have found my first planting of sunflowers, because they and the cosmos planted with them look great!
This spring I ran out of space to start seeds indoors, and since fall is a better time for planting I saved a few perennials for the fall. Last week I seeded butterfly milkweed (Asclepias tuberosa) and some columbine. In the absence of grow lights, and since I’m not an expert transplant producer, I wanted to give these seedlings a good two and a half months to grow before I transplant them.
This post was written by Amara Dunn, Biocontrol Specialist with the NYSIPM program. All images are hers, unless otherwise noted.
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
Recall from this post that I’m creating habitat for beneficial arthropods (including insects, spiders, predatory mites, etc.) around my house this spring. Because more of us may be doing this while we’re staying home to keep each other safe, I’m sharing my experiences here (as well as on Twitter and Instagram). The previous post covered site selection. Today I will talk about the species I’ve chosen (and why).
What I’m planting in my yard
My side yard faces south and gets the most sun. But it’s a pretty small area and I want it to look reasonably tidy. I’m still building rapport with my neighbors.
The front and side yards get plenty of sun (because they face south and west), so I’m looking for plants that thrive in full sun. And I’ll admit that I’m interested in more than just supporting beneficial arthropods. I also want my front and side yards to look reasonably nice. (I don’t want to make enemies of my new neighbors!) And I want to grow flowers for cutting. So I am not sticking strictly to native plant species or to perennials. Some plants I picked just because I thought they looked nice. For example, I was beguiled by ‘Chim Chiminee’ Rudbeckia. The pollen and nectar produced by the native species may have been bred out of this variety. I’ll find out. I also just love ‘Persian Carpet’ zinnias.
I grew these ‘Persian Carpet’ zinnias in my garden last year. I love the mix of colors and the abundant blooms that last well when cut.
I’ve started a lot of plants from seeds I had in my fridge (e.g., snap dragons, echinacea, bachelor’s buttons). Others I will direct-seed outside (e.g., sunflowers, zinnia, cosmos), and I may also purchase some transplants from local nurseries (many have great strategies for safe curbside pick-up!).
I’m starting some plants from seed at home. Using paper pots means that I can compost them when I’m done, and not worry about carrying pathogens over from year to year on plastic pots that I would have to wash very thoroughly after use. Once a plant pathologist, always a plant pathologist!
Choosing plants for beneficial arthropods – the basics
Which plant species to grow to support beneficial arthropods (whether it’s pollinators or natural enemies of pests, or both) is a common question. The answer is both straight-forward, and also complicated. In addition to shelter and protection from pesticides, all beneficial arthropods need something to eat. In general, plants that provide plenty of nectar and pollen help to provide this food. Many natural enemies of pests will also eat pollen or nectar (e.g., at certain life stages, or as a supplement to the pests they eat). Even if they don’t, the pollen and nectar will often attract small arthropods that natural enemies can feed on. So, the simple answer is that a plant that produces lots of pollen and nectar, will thrive in the setting where you want to plant it, and is not invasive is a good choice for supporting beneficial arthropods. Plants that are marketed as supporting pollinators are easy to find and are likely to also support natural enemies.
This Ohio spiderwort (Tradescantia ohiensis) in our beneficial arthropod habitat plots is being visited by a hover fly. Hover fly larvae are excellent aphid predators!
But, of course, it’s not exactly that simple…
Choosing plants – natives, cultivars, and more
Many people ask if they should only grow native plant species, or if it’s ok to plant cultivated varieties of native species, or non-native species. (Hopefully it’s obvious that you should never plant an invasive species in your yard!) Annie White at the University of Vermont wrote a 254-page dissertation on the topic. These two sentences from her abstract summarize her findings nicely: “Our study shows that many insect pollinators prefer to forage on native species over cultivated varieties of the native species, but not always, and not exclusively. Some native cultivars may be comparable substitutions for native species in pollinator habitat restoration projects, but all cultivars should be evaluated on an individual basis.” You might also want to take a look at this article from the University of Maryland and this one from the Xerces Society. In summary, I would say it’s up to you whether you want to plant exclusively native species, or not.
According to David Smitley from Michigan State University, perennials are usually better choices for bees than annuals, but this article includes a list of annuals that are attractive to bees. Alyssum is an annual that definitely supports natural enemies, but many of the other annuals on this list may also support natural enemies.
Although they are annuals, sunflowers are still very attractive to bees. Also, I like them as cut flowers.
Choosing plants – attracting specific arthropods
If you are trying to attract very specific natural enemies (e.g., parasitoid wasps, lady beetles) your plant choice can also get more complicated. Some great work has been done by researchers at Michigan State University documenting which arthropods (pollinators, natural enemies, and some pests) visited different plant species native to Michigan. They also offer a simplified summary. “Habitat Planning for Beneficial Insects” from the Xerces Society includes notes in the charts at the end about which beneficial insects are particularly attracted to the species listed. This resource from Oregon State University describes some specific plants and the arthropods they support. Finally, although this study was conducted in the United Kingdom, there might be some relevance to the Northeast U.S.
Update: During Summer 2020 (while I was doing less field work), I reviewed the literature I could find on the value of specific plants for specific natural enemies. Here is the spreadsheet I compiled.
Lists and searchable databases
In addition to the resources already listed, you may find the following helpful in selecting plants:
If you want to focus on native plants, there are many organizations committed to supporting local native plants…too many to list here, but some online searching may turn up an organization that is local for you.
My current plant list
This table lists what I either have already seeded (inside or outside), or am planning to direct seed outside when it gets a little warmer. In addition to the common, scientific, and cultivar name of each plant and whether it is a perennial or an annual in NY, I also included information about why I chose it. I only marked plants as supporting bees or natural enemies if I could find documentation of that fact in the resources above. It may be that more of the plants on this list support beneficial arthropods. If you have additional information on these plants, please let me know! In some cases (for example, zinnia) the species is reported to support beneficial arthropods, but I don’t know if the cultivars I’m growing will. In many cases, the decorative value of the plant was a big part of why I chose it. The arnica? Well, I just saw that in a seed catalog this winter and ordered some on a whim.
Common name
Scientific name
Cultivar
Annual or Perennial in NY
Bees
Natural enemies
Decorative
Arnica
Arnica chamissonis
perennial
Bachelor’s buttons
Centaurea cyanus
annual
X
X
Blanketflower
Gaillardia aristata
Burgundy
perennial
X
X
X
Blue vervain
Verbena hastata
perennial
X
Calendula
Calendula officinalis
Remembrance Mix
annual
X
X
Celosia
Celosia argentea cristata
Red Flame
annual
X
X
Cosmos
Cosmos bipnnatus
Dwarf Sensation
annual
X
X
X
Echinacea
Echinacea purpurea
perennial
X
X
Marigold
Tagetes erecta
Senate House
annual
X
X
Poppy
Papaver somniferum
Frilled White Poppy
annual
maybe
X
Poppy
Papaver sp.
seed saved by a colleague
annual
maybe
X
Pyrethrum daisy
Chrysanthemum cocineum
perennial
X
Rudbeckia
Rudbeckia hirta
Chim chiminee
perennial
maybe
X
Snap dragon
Antirrhinum majus
annual
X
X
Strawflower
Xerochrysum bracteatum
annual
X
Sunflower
Helianthus anus
Mammoth Greystripe
annual
X
probably
X
Sunflower
Helianthus anus
Evening Sun
annual
X
probably
X
Sunflower
Helianthus anus
Sonja Dwarf
annual
X
probably
X
Zinnia
Zinnia elegans
Queen Lime with Blush
annual
maybe
X
Zinnia
Zinnia elegans
Candy Cane Mix
annual
maybe
X
Zinnia
Zinnia elegans
Benary’s Wine
annual
maybe
X
Mexican zinnia
Zinnia haageana
Persian Carpet
annual
maybe
X
This post was written by Amara Dunn, Biocontrol Specialist with the NYSIPM program. All images are hers, unless otherwise noted.
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
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:
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.
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
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”.
Temporary update: As of January 2024, this app is in the process of being updated and is not currently available. Hopefully a new and improved version will be available again soon!
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, apps, 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.
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 has put their compatibility information into an app for Android and Apple devices. Select pesticides by either active ingredient or commercial product 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 results include information on toxicity to different life stages of the beneficial organisms and persistence of the product.
BioWorks provides a table of the compatibility of their products with pesticides, fertilizers, and adjuvants. You can filter the table by several criteria to find the information you’re looking for.
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 protect. 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.
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), Heterorhabditisbacteriophora, Steinernema, Steinernemafeltiae, Steinernemacarpocapsae
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
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)
many insects (target pest depends on fungal species and strain)
Paecilomyces (=Isaria) fumosoroseus, Beauveriabassiana, Metarhiziumanisopliae (= 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, the 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. I am starting to create biopesticide profiles that include available compatibilitiy information for these products.
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
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:
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.
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.
I was so excited to check on our Christmas tree and beneficial insect habitat plots on this sunny May day!
Thanks to everyone who’s been following the project I’ve been working on with Betsy Lamb and Brian Eshenaur to establish (and document the impacts of) habitat for natural enemies of pests and pollinators (collectively, beneficial insects) around a research planting of Christmas trees! For many people, life does not look the same as it did in January, and we are no exception. Don’t worry, we and the excellent Field Research Unit staff at Cornell AgriTech will be maintaining our research beneficial insect habitat plots (and the Christmas trees around them) so that we can continue to do research here in future years. But, in the interest of keeping people safe and working remotely as much as possible, we won’t collect insects this season. I will be going out about once a week to take pictures of both plants and insects (by myself, with a mask on hand just in case). You can see these pictures on either my Twitter or Instagram accounts.
Zizia aurea (golden alexander) is the earliest-blooming plant species we have in our beneficial insect habitat plots. And it wasn’t blooming yet the first week of May.
There’s also a new project you can follow this spring and summer (here, and on Twitter and Instagram)! I recently moved into a new house, and was already planning to put in a (mostly flower) garden, including plants that support beneficial insects. Since many people are doing more things at home, this seemed like a good year to share my experience establishing habitat for beneficial insects in a home garden.
First step? Site selection. My backyard is a bit shady (and I suspect it will be shadier when the leaves come out). You can’t tell from this picture, but the ground also tends to be a little squishy after it rains.
Even before the leaves have come out, I can tell that my backyard is not going to be the sunniest.
The front and side yards face south and west and are drier.
The side yard at my house faces south, and gets more sun (except first thing in the morning).
In my experience, the list of plants that support beneficial insects is longer if you have plenty of sun and reasonably dry soil. This doesn’t mean that you can’t support beneficial insects in a wet and/or shady spot. But you need to choose plant species carefully. You will be more successful if you choose plants that will thrive in the conditions you have. More on plant selection in a later post.
In addition to simple aesthetics, another important part of site selection around the home is knowing what’s underneath the ground. My local utility company provided information about getting water, gas, electric, and internet service lines on my property marked before I start digging. They recommended marking these lines even if I’m just planning to dig by hand with a shovel. If you are planning to use larger equipment, this is even more important (and may be required, depending on where you live). Better safe than sorry. Call before you dig!
My buried gas line runs through the side yard. I got it marked before I started digging.
Out of an abundance of caution, I’m going to use the location of the buried gas line on my property as a good place to locate a path (rather than a flower bed that requires digging).
I’ll talk more about weed control in a future post, but when you are selecting a site (and deciding how big an area you want to plant), you should also be thinking about how you are going to manage weeds. I am planning to get mulch. But I have resigned myself to the fact that I may be doing some extra hand weeding this summer. It will be a good activity to get me out of the house in the evenings and on the weekends.
Stay tuned for more updates on this project!
This post was written by Amara Dunn, Biocontrol Specialist with the New York State Integrated Pest Management Program. All pictures in this post were taken by her.
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
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).
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).
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.
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.
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.
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
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:
Golden alexanders (Zizia aurea)Catmint (Nepeta faassinii)Coreopsis (Coreopsis lanceolata)Tall white beard tongue (Penstemon digitalis). Obviously not all of these flowers are white!Ohio spiderwort (Tradescantia ohiensis)Anise hyssop (Agastache foeniculum)Echinacea (Echinacea purpurea)Orange coneflower (Rudbeckia fulgida var. fulgida)Boneset (Eupatorium perfoliatum)Wild bergamot (Monarda fistulosa)Common milkweed (Asclepias syriaca)NY Ironweed (Vernonia noveboracensis)Showy goldenrod (Solidago speciosa)New England aster (Symphyotrichum novae-angliae)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).
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.
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.
Blackeyed susan (Rudbeckia hirta)
And here’s the partridge pea:
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.)
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:
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
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?
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
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
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
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
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.
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).
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?
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.
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
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.
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.
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.
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.
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.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.
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 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
This post was written by Anna Wallis, Kerik Cox, and Mei-Wah Choi (all from Cornell’s School of Integrative Plant Science, section of Plant Pathology and Plant-Microbe Biology). Thanks for sharing your research with us!
Since this is a slightly longer post, here’s a little table of contents:
Streptomycin is a clear asset in the fire blight arsenal—it is inexpensive, effective, and reliable. However, antibiotics may not always be a viable option. More and more, biological materials are holding their own in the fight, with an increasing number of products on the market claiming protection for both blossom and shoot blight. Biological materials are still relatively new to the apple scene, an industry with a long track record of effective disease management. So why change to biologicals, and how do they work?
There are a multitude of reasons driving the growth of antibiotic alternatives. Organic production eliminated antibiotic use in 2014 in the United States. In European markets, they are prohibited or severely limited. Pressure from regulatory organizations and markets to use more sustainable management techniques will not be slowing any time soon. The prevailing evidence supports that responsible streptomycin applications do not seem to select for resistance in the pathogen. Yet, resistance continues to appear in commercial settings.
So, what are these biological materials and how do they work? In the ‘What is Biocontrol?’ tab above, Amara provides an excellent overview of biocontrol, as defined by the EPA and industry. Here I’ll review the biological modes of action and specific materials available in the context of fire blight management. I’ll also provide a snapshot of how biological programs have performed in our research orchards. There is no intention to endorse any specific trade products, rather this is an attempt to provide a neutral perspective and overview of the current market.
Biological Modes of Action
Biological materials available for fire blight management are typically biopesticides falling into the biochemical or microbial category. This means they are derived from natural sources (i.e. plant extracts or minerals) or they are composed of microcorganisms and/or their products.
To understand how biologicals can be used in fire blight management, it’s first important to review the important features of the disease. A thorough description of the disease cycle, symptoms, and causal organism can be found on this Cornell Fact Sheet. Fire blight is caused by Erwinia amylovora, a bacterial pathogen which preferentially colonizes the floral surface, specifically the stigma or the sticky part of the tip of the female organ. First, enough heat must be accumulated for colonization to occur, which can be predicted by disease forecasting models such as MaryBlyt (if you’re familiar with the disease and pest prediction tool NEWA, this is the model used in the fire blight prediction model there). Then there must be a wetting event to wash the bacteria into the natural openings in the flower, the nectary at the base of the floral cup. Unlike fungi, bacteria cannot penetrate plant cells directly, so they rely on natural openings and tissue damage to invade their host.
Figure 1. Simplified disease cycle for Erwinia amylovora, causal agent of fire blight. Clockwise from top left: primary inoculum is produced in the spring as bacterial ooze from old cankers; inoculum is transferred to open flowers and causes blossom blight; blighted blossoms provide additional inoculum which is transferred to young leaf tissue damaged by wind or hail causing shoot blight; bacteria may also travel systemically via the vascular system of the plant leading to canker blight; cankers produced from blossom, shoot, or canker blight provide an overwintering site for bacteria to colonize the tree in the following season.
Biologicals can disrupt these events by:
Outcompeting the bacteria during colonization of the plant
Producing antibiotic metabolites, killing the pathogen prior to infection, or
Priming natural host defenses, making the plant more resistant to the bacteria. This is called ‘Induced Resistance’
A simplified view of these events is depicted in Figure 2.
Figure 2. Depiction of fire blight blossom infection and how biological materials interfere. (A) In order for a blossom infection to occur, flowers must be open and receptive, heat accumulation must be sufficient for E. amylovora to colonize the stigma (red circle), and there must be a wetting event (blue arrow) to wash the bacteria into the floral nectary. (B) Biological materials protect against infections by outcompeting the pathogen or producing antibiotic metabolites (yellow ‘x’) or priming host defenses (red letter “T”).
Like any product, these materials require precise applications, to ensure they are in the right place at the right time to provide effective control (Figure 3). Materials with competitive action or antimicrobial metabolites that ‘protect’ the flower (protectants) must be applied when the bacteria is present or just before. This enables sufficient, timely colonization or interaction with the pathogen. Induced resistance materials (defense inducers), also called Systemic Acquired Resistance or Induced Systemic Resistance materials (SARs or ISRs), must be applied prior to infection events, with enough time to activate the host response. (Click the image below to enlarge it.)
Figure 3. Approximate timing of biological materials corresponding to phenological stages of apple for blossom and shoot blight protection. In any fire blight management program, it is essential to remove inoculum (old cankers) during the dormant period and apply a general antimicrobial at green tip to reduce inoculum. Blossom blight control is provided by defense inducers applied prior to bloom and protectants applied at bloom. Additional applications of defense inducers post-bloom provide shoot blight control; some of the earlier applications targeting blossom blight seem to also have some carry-over effect for shoot blight.
What products are currently available and where do they fit in?
Blossom protectant type products include both bacteria and fungi. The most well-known examples include: Pantoea agglomerans, a bacterium closely related to the fire blight bacterium and an excellent colonizer of apple flowers, marketed as Bloomtime Biological (Northwest Agricultural Products), and the yeast Aureobasidium pullulans, a fungus, marketed as Blossom Protect (Westbridge Agricultural Products). Another bacterium, Pseudomonas fluorescens, is also an effective competitor and is marketed as BlightBan (NuFarm).
Materials with antimicrobial activity are most often Bacillus species, most commonly strains of B. amyloliquefaciens and B. subtillus. Currently on the market are Serenade Optimum (Bayer), Double Nickel (Certis), and Serifel (BASF).
Products that stimulate Induced Resistance response in the host plant work by stimulating two possible pathways the ISR and SAR, as mentioned earlier. These pathways are related and overlapping in the plant, and scientists are still detangling the complex molecular mechanisms involved in plant protection. Example products include Regalia, an extract of the plant Reynoutria sachaliensis or giant knotweed (Marrone Bio Innovations) and a Bacillus mycoides strain marketed as LifeGard (Certis). Another common product used in induced defense is acibenzolar-S-methyl. This is not a biological, but a synthetically derived product marketed as Actigard (Syngenta).
Many of these products have been recommended as part of an integrative management strategy outlined in an extensive report from The Organic Center, based on results from both research trials and anecdotal experience (Ostenson and Granatstein 2013). Always follow the label on any pesticide (including biopesticides) you use.
Table 1. Biological products for Fire Blight
Product
Active Ingredient
Mode of Action
Firewall
Streptomycin
antibiotic – kills pathogen
Blossom Protect
Aureobasidium pullulans strains DSM14940 & 14941
competitive with pathogen
Bloomtime Biological
Pantoea agglomerans strain E325
competitive with pathogen
BlightBan
Pseudomonas fluorescens strain A506
competitive with pathogen
Serenade Optimum
Bacillus amyloliquefaciens strain QST713
antibiotic metabolites
Double Nickel
Bacillus amyloliquefaciens strain D747
antibiotic metabolites
Serifel
Bacillus amyloliquefaciens strain MBI600
antibiotic metabolites
Regalia
extract of Reynoutria (giant knotweed)
resistance inducer
LifeGard
Bacillus mycoides isolate J
resistance inducer
Results from the Cox lab
Our lab conducts extensive trials evaluating efficacy and sustainability of disease management programs in our research orchards at Cornell AgriTech in Geneva. More recently testing has included various biological materials. In these trials, management programs are tested in two orchard blocks: a Gala block and an Ida Red block, established in 2002 and 2004 respectively, both on B.9 rootstock. The trees in these blocks are spaced considerably farther apart than commercial orchards in order to prevent drift between treatments.
Programs targeted either blossom or shoot blight. To provide sufficient disease pressure, trees are inoculated with a high concentration of E. amylovora at bloom. In blossom blight programs, resistance inducers are applied at pink, and protectants are applied at bloom. For shoot blight programs, resistance inducers are applied at petal fall.
Disease pressure varied from season to season, as indicated by the untreated control trees, ranging from 60 to 99 % disease incidence. Across all trials, antibiotics provided the most consistent and reliable control of both blossom and shoot blight, with less than 15% blossom and 5% shoot blight. The biological materials, both protectants applied at bloom and defense inducers applied pre-infection, also provided good disease protection with typically less than 30% incidence depending on the season conditions and the product. Compared to antibiotic programs, these materials showed greater variation both within and between seasons (i.e. greater standard deviation within a treatment and different top performers in different seasons). In seasons with lower disease pressure, biological programs tended to perform as well as antibiotics. Some of the specific results from 2015-17 are shown in Figure 4 (click the image to enlarge the graphs).
Figure 4. Average disease incidence of four replicate trees treated with fire blight management programs in 2015 (A & D), 2016 (B & E), and 2017 (C & F). Programs included untreated control (grey bar; highest disease pressure), antibiotics (maroon), resistance inducers (blue), and blossom protectants (yellow).
The verdict on biologicals for fire blight management
Do we recommend biological materials for fire blight management? Overall, the answer is generally yes. There are several important considerations to consider. In our research orchards, the system is challenged with a very high level of inoculum to examine fine differences in product performance. These inoculum levels are much higher than would be present in most commercial orchards. Hence, we expect all programs would perform even better in a commercial setting. In addition, combinations of products seem to be the best: for example, pairing a defense inducer applied at bloom with a protectant material at bloom to control blossom blight, with follow up defense inducer applications for shoot blight. We also expect efficacy of biological materials to improve in the future. Changes in formulations improving activity (note the old and new Regalia formulations in Figure 3), as well as shelf life, tank mixing, and storage happen fairly regularly and will make products more accessible and affordable for growers.
Biologicals are still relatively new materials. As with any product, there is still much to learn about how products work in the field, the most effective management programs, and translating best practices from research to commercial settings. We believe they are a valuable part of an integrated fire blight management approach, including good cultural and mechanical practices such as planting resistant cultivars and rootstocks and removing inoculum from the orchard.
You can learn more from these sources:
Ostenson, H., and Granatstein, D. Grower Lessons and Emerging Research for Developing an Integrated Non-Antibiotic Fire Blight Control Program in Organic Fruit. The Organic Center. November 2013. Available at: https://www.organic-center.org/wp-content/uploads/2013/07/TOC_Report_Blight_2b.pdf
Pal, K., and Gardener, B. 2011. Biological Control of Plant Pathogens. The Plant Health Instructor, APS. Available at: https://www.apsnet.org/edcenter/advanced/topics/Pages/BiologicalControl.aspx.
Turechek, W. W., and Biggs, A. R. 2015. Maryblyt v. 7.1 for Windows: An Improved Fire Blight Forecasting Program for Apples and Pears. Plant Health Progress. 16:16–22. Available at: https://www.plantmanagementnetwork.org/pub/php/volume16/number1/PHP-RS-14-0046.pdf
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:
Kill on contact
Kill after ingestion
Repel
Inhibit feeding
Inhibit growth
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
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.
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.
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.
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.
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 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.
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.
