2022
Assessing the Efficacy of Foliar Fungicides Applied Through Irrigation for Soybean Production
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Alyssa Koehler, University of Delaware
Co-Principal Investigators:
Project Code:
PLSC43292522011/PLSCDA2211
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:
This project investigates the addition of fungicides to irrigation in soybeans in the Mid-Atlantic. Delmarva farmers have been experimenting with fungigation for over 2 decades with few, if any, replicated studies. This work aims to quantify soybean foliar disease severity in response to fungicide treatments applied through irrigation, compare efficacy of soybean foliar disease management in ground rig versus irrigation applied fungicides and share the results.
Key Beneficiaries:
#agronomists, #Extension agents, #farmers
Unique Keywords:
#fungicide, #fungicide application, #irrigation, #soybean diseases
Information And Results
Project Summary

The relatively flat topography and sandy soils of the Mid-Atlantic tend to be ideal candidates for the center pivot type irrigation that is employed on over 85% of the irrigated acreage. Irrigation research has historically been conducted in the semi-arid Southwest US, but research from other areas of the U.S. often has limited adaptability to Maryland and Delaware due to climate and soil differences. In recent years there has been an effort to optimize irrigation practices specifically for the Mid-Atlantic. As improvements are made in irrigation timing and nutrient management, new questions, such as the addition of fungicides to irrigation, can be addressed.

The application of fungicides through irrigation has not been widely investigated in the Mid-Atlantic, but could provide farmers with the option for an additional application method. From 2019-2021, initial research on efficacy for management of foliar diseases in corn were conducted at the UD Warrington Irrigation Farm. This work has generated interest from growers to determine if fungicides applied via irrigation may also be viable in soybean production.

Project Objectives

1.Quantify soybean foliar disease severity in response to fungicide treatments applied through irrigation.
2.Compare efficacy of soybean foliar disease management in ground rig versus irrigation applied fungicides. 3.Disseminate research results to Mid-Atlantic irrigated farmers.

Project Deliverables

Objective 1. Quantify soybean foliar disease severity in response to fungicide treatments applied through irrigation.

Objective 2. Compare efficacy of soybean foliar disease management in ground rig versus irrigation applied fungicides.
All of the work in this study will be conducted at the University of Delaware’s Warrington Irrigation Research Farm in Harbeson, DE. A soybean variety will be selected and planted late April- early May at 140,000 seeds per acre. Using a combination of soil electro-conductivity mapping, aerial imagery, soil borings and historical yield maps, the field will be divided into 5 tiers (replications) of varying soil type (Tier 1 = 20% wettest/heaviest soil – Tier 5 = 20% driest/lightest soil). Within each soil type tier, the research field will be divided into 11 randomized treatments and 5 replications for a total of 55 individual 90’ x 90’ plots. Fertilizer will be applied based on the University of Delaware recommendations for irrigated soybean production. Weather data will be collected by a Delaware Environmental Observing System weather station located on the irrigation research farm.

Each plot will receive one of the following fungicide treatments via chemigation/fungigation or ground rig application and will be replicated five times:
1. No Fungicide
2. Miravis Top applied at R3 via fungigation
3. Miravis Top applied at R5 via fungigation
4. Miravis Top applied at R1 and R3 via fungigation
5. Miravis Top applied at R3 and R5 via fungigation
6. Miravis Top applied at R1 + R3 + R5 via fungigation
7. Miravis Top applied at R3 via ground rig
8. Miravis Top applied at R5 via ground rig
9. Miravis Top applied at R1 and R3 via ground rig
10. Miravis Top applied at R3 and R5 via ground rig
11. Miravis Top applied at R1 + R3 + R5 via ground rig

For foliar pathogens that are present, disease severity ratings will be collected throughout the season at various growth stages. We anticipate that foliar disease pressure may be low, but that differences in Septoria brown spot could be present. Although not historically associated with yield loss, recent trials in DE and further south have shown yield loss when Septoria brown spot moves up the canopy earlier in the growing season. Plots will be harvested with a plot combine to determine yield, moisture, and test weight differences. Disease ratings and yield data will be analyzed to determine treatment differences among fungigation and ground rig application methods and timings. Fungicide cost as well as application frequency will be analyzed for economic implications of each treatment. Data from this trial will be used to measure disease severity and yield response to assess potential of applying fungicides through irrigation for soybean diseases in the Mid-Atlantic.

Objective 3. Disseminate research results to Mid-Atlantic irrigated farmers.
Findings from this project will be shared through the University of Delaware’s Weekly Crop Update which reaches over 700 growers, consultants, and stakeholders and provides a platform to discuss disease concerns and other production issues. Data will also be shared through training events and extension presentations such as Mid Atlantic Crop School, and the 2023 Delaware Ag Week.

Progress Of Work

Update:
Soybeans were planted at the Warrington Irrigation Farm on 5/19/22. Plots were divided into 90'x90' blocks to receive one of the following treatments:

1. No Fungicide
2. Miravis Neo applied at R3 via fungigation
3. Miravis Neo applied at R5 via fungigation
4. Miravis Neo applied at R1 and R3 via fungigation
5. Miravis Neo applied at R3 and R5 via fungigation
6. Miravis Neo applied at R1 + R3 + R5 via fungigation
7. Miravis Neo applied at R3 via ground rig
8. Miravis Neo applied at R5 via ground rig
9. Miravis Neo applied at R1 and R3 via ground rig
10. Miravis Neo applied at R3 and R5 via ground rig
11. Miravis Neo applied at R1 + R3 + R5 via ground rig

R1 applications were made 7/10/22 for fungigation and 7/13/22 for ground rig. Mechanical issues with the tractor delayed ground rig application. R3 applications are scheduled for 7/28/22 ground rig and 7/30/22 for fungigation and R5 will be initiated once the growth stage is research. After R5 application, plants will be rated for any foliar disease. We are also hoping to use drone imagery to capture any differences in canopy visible from aerial view. Plots will be harvested to compare yields across treatments.

Final Project Results

Update:

View uploaded report PDF file

Center pivot irrigation is widely used across the Mid-Atlantic. Irrigation research has historically been conducted in the semi-arid Southwest US, with limited adaptability to Maryland and Delaware due to climate and soil differences. In recent years there has been an effort to optimize irrigation practices specifically for the Mid-Atlantic. As improvements are made in irrigation timing and nutrient management, new questions, such as the addition of fungicides to irrigation, have been raised. The application of fungicides through irrigation has not been widely investigated in the Mid-Atlantic, but could provide an additional application method to farmers. Project objectives included: 1) Quantify soybean foliar disease severity in response to fungicide treatments applied through irrigation. 2) Compare efficacy of soybean foliar disease management in ground rig versus irrigation applied fungicides. 3) Disseminate research results to Mid-Atlantic irrigated farmers. In 2022, disease pressure was limited with insufficient disease levels to take severity ratings. Ground rig applications had higher NDRE values indicating higher chlorophyll content in plants receiving fungicide application by this method. Although there were visual differences in NDRE, no effect on yield was observed. Further replications of this experiment will be conducted in 2023 to gain additional data comparing fungicide application by ground rig versus fungigation at various timings in soybean. The goal of this project is to assess the efficacy of fungicides applied via fungigation in comparison to ground rig applications at multiple application timings to inform application method recommendations for soybean farmers.

Benefit To Soybean Farmers

Research on irrigation of agronomic crops in the Mid-Atlantic region has been limited until recent years. Delmarva farmers have been experimenting with fungigation for over 2 decades with few, if any, replicated studies. Adkins, Whaley & Sylvester explored fungigation of corn at the UD Warrington Farm in 2018 to evaluate the accuracy of the chemigation system and provide initial data for setting up more advanced tests. This work was continued by Koehler and Adkins from
2019-2021, where it was shown that fungicides applied through irrigation reduced disease severity of grey leaf spot in corn, with variable yield effects. To date, there have been no replicated trials assessing efficacy of fungicides for foliar diseases of soybean when applied through irrigation.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.