Progress report for ONE24-443
Project Information
We aim to quantify the best management strategies that
sustainably reduce white
mold's impact on soybeans in Pennsylvania. Participatory on-farm
field trials will
assess the benefits of selecting shorter maturity group soybean
varieties and using
biological seed treatments, which will be paired with unmanned
aerial vehicle (UAV)
fungicide applications. Using UAVs to apply fungicides will
enable spot spraying of
white mold hot spots, reducing fungicide use and environmental
impact. UAV fungicide
application spray coverage will be compared with traditional
ground applications in
replicated strip trials. The use of UAV applications is
increasing, yet many questions
remain regarding their use and efficacy. Soybean growers across
Pennsylvania are
interested in testing these management strategies due to annual
yield losses from
white mold. Our farmer partners have expressed interest in
participating in these trials
using known white mold infested fields and drone technology. The
objectives are i) to
determine if a shorter soybean relative maturity group results in
lower white mold
severity, ii) to test the efficacy of a biological seed treatment
against white mold, and
iii) to determine if UAV-applied fungicides can effectively
minimize the amount of
chemical and number of applications needed to manage white mold.
Results from
these trials will be incorporated into extension talks and
handouts. We will conduct
soybean grower breakfast meetings to inform participants and
other local growers
about the results of the trials and inform them about more
sustainable management
strategies for managing white mold in soybeans.
-
To determine if a shorter soybean
relative maturity group results in lower white mold
severity. -
Test the efficacy of biological
soybean seed treatment compared to traditional
fungicides. -
To determine if UAV-applied
fungicides can effectively minimize the amount of chemicals and
number of applications needed to manage white mold compared to
current practices. -
To communicate results to our farmer
partners and other local growers through grower meetings and
extension materials.
Hypotheses
-
We hypothesize that the use of
shorter maturity soybean varieties will decrease white mold
disease incidence and severity. In a wet year, with conducive
conditions that allow for high levels of white mold
development, shorter maturity soybeans will have a short
flowering period, reducing the infection window, thus leading
to increased yield. -
The Heads Up seed treatment will
have a lower disease severity index than the untreated check,
but the application of fungicide at R2 will outperform the seed
treatment. Application timing is key in white mold management,
and we hypothesize that the seed treatment will not sufficient
residual activity compared to a well-timed fungicide
application. -
Finally, drone application of
fungicides will be more effective against white mold because
the propellers help to push the product into the soybean canopy
to protect flowers better. In particular, the DJI Agras T40
should perform better because its nozzles produce finer
droplets for better coverage. -
The Esker Lab and Penn State Field
and Forage crop team will present recent white mold disease
management data at crop days and other extension meetings. We
will provide growers with the best information on
cultural, biological, and precision management to more
sustainably manage white mold.
Problem
Soybean farmers deal with numerous diseases that impact plant
health and yield. White mold is a fungal disease caused by the
pathogen Sclerotinia sclerotiorum. It is the second most
yield-limiting disease of soybean in Pennsylvania, causing
approximately 5.29 million USD per year (Bandara et al. 2020).
The pathogen is a generalist that affects many other crops,
including legumes, canola, sunflowers, and weed species.
White mold in soybeans is a difficult pathogen to manage. The
overwintering fungal structures, called sclerotia, can survive in
the soil for up to 5 years (Heffer Link and Johnson, 2007). Once
a grower has white mold in a field, driving the inoculum down to
zero is challenging. In addition, spores from the fungal fruiting
bodies can travel up to one hundred meters from the point of
inoculum (Ben-Yephet and Bitton, 1985). The pathogen also spreads
on equipment and gets harvested along with the seed, causing
contamination. Weed species that act as hosts of the pathogen can
help increase the
inoculum in the soil. S. sclerotiorum prefers cool, humid, wet
weather during soybean flowering. These conditions promote
disease development during the time of soybean flowering.
Growers with a history of white mold often spray preventative fungicides to protect soybean flowers from the fungal spores. Growers commonly applied one or two fungicide applications during the primary soybean flowering period (R1 through R3 growth stages). Because the primary fungicides for white mold are preventative, the presence of symptoms means it is too late to spray. This presents the problem of growers applying fungicides when environmental conditions do not warrant it, and they apply broadly across the entire field.
Solution
While management tactics exist for white mold, growers must use
an integrated management strategy including scouting their fields
to identify hotspots. White mold is not uniformly distributed
across a field but tends to be more aggregated in cool, wet
spots. The spatial knowledge generated by scouting allows farmers
to consider more site-specific (and precision) disease
management.
Many IPM practices can help reduce the impact of white mold. Growers can plant shorter relative maturity group varieties and varieties that are tolerant to the disease. There are no completely resistant soybean varieties, though some are less susceptible. Cultural practices like growing a less bushy variety help to open the soybean canopy and prevent wet and humid conditions. Other cultural tactics to management include using wider row spacing and lower seed populations to decrease disease risk. Some biological approaches are available. Growers can spray biologicals, like Contans (Coniothyrium minitans), to reduce white mold in a field, although the cost and efficacy limit use.
We hypothesize that integrated disease management that integrates tolerant varieties, shorter maturities, and 30-inch row spacing can reduce the impact of white mold. Even with this, our stakeholders have indicated that applying some methods on their farm operation may not be feasible. For example, production practices like lengthening the crop rotation by adding a small grain would decrease viable inoculum in the soil. However, growers who do not typically grow small grains may not have the equipment to incorporate that practice on their farm. As such, they must rely on other cultural controls like variety selection and planting date. Evaluation of different management strategies is crucial for many growers who need help to afford to invest in other productions practices or rely on chemical applications. Incorporating several cultural management strategies against white mold is critical because of the lack of complete varietal resistance.
The technology of UAV pesticide application is advancing rapidly. Continual tests with application drones such as the DJI’s Agras T40 are being conducted to determine its coverage on crops and drift risks (Thompson et al. 2024). The Agras T40 applies chemicals using dual centrifugal atomizing discs rather than the traditional hydraulic Teejet nozzles of the Agras T30. The atomizing discs provide finer droplets and more easily apply variable rates than hydraulic nozzles (Gong et al. 2019). These advancements in spray nozzles may help improve coverage and efficiency white mold in soybeans because of the need to spray flowers lower in the soybean canopy.
Integrating scouting to identify white mold hot spots with drone technology offers farmers the potential to reduce prophylactic sprays across soybean fields. This has the added advantage of lowering fungicide, chemical, and labor costs, providing the applicator with a safer method (Gibbs et al. 2021; Kim et al. 2023). Precision applications are much more manageable with drones with better rate control and easier maneuverability than ground rigs. Pennsylvania’s hilly terrain and diverse soybean field shapes require increased mobility in pesticide applications. Recent advances in drone capacity have encouraged farmers to consider their use as an approach to make fungicide applications more efficient. During winter meetings in 2024, there has been an increase in inquiries from growers regarding the safety and regulations on drone application of fungicides. Agricultural drone technology is advancing quickly, and growers need clear, up-to-date information on the topic to determine its fit in their farm operations.
Cooperators
- - Producer
- - Producer
Research
2024 Annual report -- This is an in-progress report. We have approximately 12 winter talks highlighting the current efforts, plus several breakfast meetings. We hope to identify additional cooperators and will update the details in our report once the winter extension is completed.
Methods as proposed:
Field trials will consist of a randomized strip-trial design with two years of testing. In Centre County, the additional factor will be the soybean relative maturity trial. The additional factor in Cambria County will be the Heads Up biological seed treatment. All three locations (additional location is in Lawrence County) will incorporate drone. Please see the attached maps and treatment lists in the Supporting Materials.
At the Centre County location, the maturity group trial will be planted in strips by our farmer cooperator, Mountain Edge Farm, using a split planter with 6 rows planting a 2.6 maturity group variety and the other 6 rows will be 2.8 maturity group. Another planting strip will compare two different 3.3 maturity group varieties (6 rows each) to compare varieties with the same maturity group, but different white mold tolerance ratings. These planted strips will be separated into four plots using bamboo stakes and flags. These plots will each have disease assessments completed, with strips harvested separately. All other production practices will remain the same.
The biological seed treatment trial will be set up using a split planter by our farmer cooperator in Cambria, with half the planter with Heads Up seed treatment and the other half without Heads Up. The rest of the field will be planted using Heads Up. Plots will be set up using bamboo stakes and flags to mark the untreated area. These plots will each have disease assessments completed and be harvested separately. At the R2 growth stage, half of the untreated area will be sprayed with Aproach at 9 ounces per acre, and the remaining will remain the untreated check. If our farmer cooperator has time during planting, he will plant this trial at two different planting dates to address the question of early versus late planting dates on white mold development.
The comparison between UAV and ground rig application methods will take place at all three locations and consist of four treatments. Fields will be planted and follow typical production practices until the R2 growth stage. Treatments will be replicated four times, and the sixteen plots will be sprayed in strips by the drone and the backpack sprayer. Each of the thirty-two plots per location will be 50 feet long. Plots sprayed by the drone will be 27 feet wide, and the backpack-applied plots will be 15 feet. Backpack plots will be sprayed with the CO2 backpack prayer using traditional TeeJetÒ flat fan nozzles. The drone application at the Lawrence County location will be done using a DJI Agras T30 at 3 gallons per acre by our farmer cooperator Rick Telesz. The Centre and Cambria locations will be applied using a DJI Agras T40 at 3 or 6 gallons per acre by Tyler Fleck, a local custom applicator. During fungicide applications, weather data will be recorded, and wind speed and direction will be recorded prior to each treatment.
Fungicide treatments in the application comparison trial will include an untreated check for drone and backpack strips. Treatments will include 9 ounces per acre Aproach at R2 growth stage, 5 ounces per acre Endura at R2, and Aproach at R2 and 10-14 days after. An adjuvant of 0.25% v/v NIS will be used for all applications.
Data Collection
In the seed treatment trial, initial stand counts and Canopeo/Greenseeker data will be collected from the Heads Up-treated area and the untreated area. Throughout the growing season, photos will be collected regularly to note the canopy closure across all trials.
Fields will have the Sporecaster risk monitored throughout the flowering period to note the disease risk in all trials. Weather data will be collected from Bushel Farm, which provides precipitation and growing degree days from planting. Growth stages will be monitored closely to ensure accurate fungicide applications are made at R2.
At the time of fungicide application, water-sensitive paper will be placed in the middle three rows of each plot that will receive a drone or backpack application. SpotOn paper will be used, and the plot number, row number, and height of the paper will be written on the back of the card. Cards will be attached to plot stakes at the appropriate height- 6 inches or 2 feet above ground level. Immediately following the fungicide application, papers will be retrieved and photographed using proper PPE.
Disease assessments will be conducted at the R5 growth stage (beginning seed). Fifty plants in each plot will be assessed on a scale of disease severity between 0 and 3. “0” is no disease; “1” is disease on lateral stems; “2” is disease on the main stem; and “3” is dead plant/pod abortion. The disease severity index percentage will be calculated for each plot.
Harvest
At harvest, plot yield will be weighed using a weigh wagon scale. Weight will be divided by plot sizes to get pounds per plot. Test weights will be used to calculate the bushels per acre. A subsample from each plot will be collected to test for moisture and test weight. Notes will be made on the grain's quality regarding the amount of sclerotia in the seed lot.
Analysis
WSP images will be analyzed using ImageJ software, which provides higher-resolution data compared to the SnapCard app used in the preliminary study. Each image will have the region of interest identified to reduce imperfections (tears, drift, fingerprints, etc.) from being analyzed. ImageJ will identify the pixels that represent droplets and measure the size and overall coverage of droplets on the WSP image. These data will be analyzed to compare application method treatments.
Disease assessment data will also be used to continue the validation of the Sporecaster mobile application for forecasting white mold. The disease assessments for untreated checks for each field will be averaged and compared to the Sporecaster risks and weather data to determine the accuracy of the Sporecaster models. Weather data will be summarized and reported for each location to note the general disease pressure.
All disease and yield data will be analyzed using a generalized linear mixed model in R using the lme4 package in R. Means for each treatment (maturity group, seed treatment, fungicide application method, fungicide product, and possibly planting date) will be compared to untreated checks and separated to determine significant differences among treatments. Data from all location-years will be analyzed together where applicable.
Economic analysis will be completed after year two to determine if drone application of fungicide pays off compared to traditional ground rig applications. This analysis will consider the current product costs and custom applicator rates for drone and ground rig applications. These results will better provide growers with information about the economic feasibility of drone application of fungicides. The costs and payoff of fungicide application will be compared to the payoff from utilizing other cultural methods, such as seed treatment, maturity group, and planting date.
Education & Outreach Activities and Participation Summary
Participation Summary:
This proposal includes funding to host two breakfast meetings with our cooperators. The 2023 growing season was one of the worst years for white mold incidence in Central PA. Therefore, many growers have an interest in learning new management strategies for white mold. The small breakfast meeting style has allowed the best conversation between growers and researchers to receive valuable feedback and grower needs. With just a few growers participating, growers tend to be more open about their production practices and disease management on their farms. This project includes ideas from our farmer partners, and we want to provide trial organization and data collection to measure differences among the treatments they suggested. We have already established good relationships with these farmer partners, and we want to continue to get feedback on our research so they can improve their disease management practices and bottom lines.
These discussion meetings will be conducted at local cooperative extension buildings or restaurants. Since growers tend to be available during breakfast or lunch, a meal will be provided to those who participate. During the meetings, our team will present results from the previous year’s trial, and participants will have the opportunity to ask questions and voice comments and concerns about the research. Grower discussion meetings will be conducted using open-ended questions to determine their priorities and needs in future research projects. The meeting will focus on growers’ perspectives on white mold incidence and risk, and white mold management strategies will be evaluated against each grower's situation.
Beyond our partner farmers, this project will produce data relevant to soybean growers across Pennsylvania, and results will be shared at various extension meetings and Penn State crops days. Growers are often presented with various data about the effectiveness of fungicides and new UAV technologies. We need to provide unbiased third-party results they can trust to determine which management tactics to use. Using our trial data, our extension team has developed presentations on white mold in soybeans over the past several years. These results are shared with the entire Penn State Field and Forage crop team to be disseminated across the state. This research is valuable for informing growers about the latest management techniques from year-to-year.