I’m excited to announce that the New York State IPM Program has a new resource – Biopesticide Profiles!
(Scroll down to the bottom of the page linked above, past the efficacy summaries, which are also cool.)
So far, we have profiles for nine biopesticides registered for use on various crops in NY (including one for use in home gardens) against plant diseases. I plan to add more profiles over time, and will definitely add some bioinsecticides in the future.
These profiles are not meant to replace pesticide labels; always read and follow the label and only use pesticides that are currently registered in your state or province. These profiles have practical details about how to use biopesticides most effectively, including information on mode of action, compatibility with other pesticides, best storage conditions, and shelf life. I’ve also included information on any known toxicity concerns for not just bees, but other beneficial insects like natural enemies of pests.
I collected this information from pesticide labels, pesticide manufacturers, EPA registration documents, and peer-reviewed literature, to save you time when you’re considering using a biopesticide. But you should still always read the label.
Take a look and let me know what you think! Which biopesticides should be next on my list?
This post was written by Amara Dunn, Biocontrol Specialist with the NYSIPM program. Support for this project was provided by the NY Farm Viability Institute.
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:
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?
Can you get better control of white mold in green beans by Contans prior to planting, and Double Nickel at bloom?
What are the costs (versus benefits) of using these biofungicides in these ways?
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.
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.
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.
Labor Day weekend may be viewed by some as the end of summer, but farmers know that the summer growing (and harvesting!) season is far from over. Similarly, the field projects I’m involved with this summer (read more here and here) are still running. Over the fall and winter I’ll be analyzing data and sharing results (on this blog, and at winter meetings). In the meantime, here’s a pictorial summary of my summer projects (so far).
The field projects I’ve just described will be wrapping up in September. Check back to learn about the results. Better yet, click the green “Subscribe” button towards the top and right of this page, and you’ll receive an email when a new post is available!
In the meantime, there will still be at least a few more weeks of pictures posted regularly on Twitter (@AmaraDunn) and Instagram (@biocontrol.nysipm).
Creating habitat for beneficial arthropods was 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 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.
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.
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.
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.
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 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!
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.
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.
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.
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.
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.
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.
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.
Quantify what biofungicides add to management of cucurbit powdery mildew and white mold in terms of…
– disease control
– yield
– plant health
– economic value (comparing yield gains to fungicide costs)
Evaluate the utility of NDVI (normalized difference vegetation index) as a measure of plant health and disease detection in fresh vegetables
Why this project?
For both diseases (cucurbit powdery mildew and white mold), we’re considering biofungicides used with other pest management – other biofungicides, conventional chemical fungicides, and/or cultural practices. Biofungicides are not expected to be silver bullets, and they work best when used in an IPM strategy. But when deciding whether or how to use them in your operation, it’s good to know what value you’re getting for the extra costs of purchasing and applying the products. This summer we ran trials in three major vegetable-producing regions of the state: western New York, eastern NY, and on Long Island.
Biofungicides for cucurbit powdery mildew
For combatting cucurbit powdery mildew, we’re comparing three biofungicides: LifeGard (Bacillus mycoides isolate J), Regalia (extract from the giant knotweed plant Reynoutria sachalinensis), and Serifel (Bacillus amyloliquefaciens MBI 600). All three were applied weekly starting when the plants were small. Then, when the first signs of powdery mildew showed up, we started a rotation of conventional fungicides (Vivando, Quintec, and Luna Experience). These three treatments plus a rotation of all-organic fungicides (LifeGard, MilStop, Serifel, and a mineral oil) are being compared to two control treatments: the conventional fungicides alone, and plants that received no treatment for powdery mildew. We ran the trials on a variety of bushing acorn squash (‘Honey Bear’) that has intermediate resistance to powdery mildew.
Biofungicides for white mold
In the white mold trial, we’re looking at Double Nickel (Bacillus amyloliquefaciens strain D747) alone or in combination with Contans (Paraconiothyrium minitans strain CON/M/91-08; formerly Coniothyrium minitans). Next year we’ll look at these biofungicides in combination with reduced tillage at one site. Reduced tillage is another IPM strategy for white mold. The active ingredient in Contans is a fungus that eats the resting structures (sclerotia) of the fungus that causes the disease white mold. Because of this, it needs time to work, and is applied either in fall or spring. The goal is to reduce the number of sclerotia present in the next crop. Next year we’ll collect data on whether application of Contans reduced disease. In the meantime, during the 2018 growing season treatments we tested were Double Nickel, Cueva (an OMRI-approved copper) and no treatment for white mold on snap bean. Previous research by the EVADE Lab at Cornell AgriTech at The New York State Agricultural Experiment Station, Geneva, New York, has shown that Double Nickel is a promising biofungicide for white mold.
What is NDVI, anyway?
In a nutshell, the “normalized difference vegetation index” (NDVI) is a way to quantify how much healthy, green foliage is present. The device we used emits different types (wavelengths) of light (red and near infrared), and measures how much of each type of light is reflected back from the leaves of the plant. Leaves that are dark green and healthy reflect more infrared light and absorb a lot of red light. Less healthy leaves reflect less infrared light. A NDVI value closer to 1 indicates healthier plants. A NDVI value closer to 0 indicates less healthy plants (or more bare ground).
Help us quantify the health of plants. Even though NDVI is not a measure of disease, we would expect to see more healthy foliage if biofungicides are contributing to disease control.
Provide some preliminary data to help us determine whether NDVI measurements could be useful to NY fresh vegetable growers.
Field meetings were held at each powdery mildew trial location so that local growers could see the trials and hear about the project. We’re currently wrapping up data analysis from the 2018 field season. You’ll be able to learn about results from the first year of this two-year project at winter meetings around NY, in extension newsletters, and here on this blog. Also, stay tuned for Part 2 of this post with details about how these biofungicides work (modes of action), and how to use them most effectively.
This post was written by Amara Dunn (NYS IPM), Sarah Pethybridge (Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University), and Darcy Telenko (Department of Botany & Plant Pathology, Purdue University).