We propose to conduct on-farm trials and laboratory experiments that 1) use
low-cost, DIY spore trapping instruments and a quantitative PCR method to
determine the presence and quantity of the fungal pathogen Cercospora sojina
(i.e., the causal agent of frogeye leaf spot of soybean) and 2) monitor on-site
environmental conditions that correlate with disease progression during soybean
growing season for the development of an open-access decision support system
through building airborne inoculum surveillance networks in Virginia’s soybean
production areas. To aid in fungicide application decision-making, 3) we also
plan to assess the benefit of variety resistance with and without fungicide
applications for managing frogeye leaf spot.

1) Determine the presence and abundance of fungal pathogens in air samples
and environmental conditions that correlate with the development of frogeye
leaf spot disease and yield reduction in soybean fields.
2) Construct mathematical models including factors that predict frogeye leaf
spot disease development to guide fungicide application.
3) Assess the benefits of foliar fungicides used to control frogeye leaf spot on
soybean varieties with varying levels of resistance to the disease.

We will use the results of this project to make recommendations on the selection
of soybean variety and fungicide application/timing for Virginia soybean
growers. The qPCR assay developed from this project will be provided to our
growers through the PI’s website (zenglab-pdepmi.com). Each participating
grower will be provided with a unique link for accessing weekly pathogen
population data and on-site weather information.
The in-season C. sojina airborne inoculum will serve as an early warning indicator
of soybean frogeye leaf spot disease development. Through this project, we will
construct an initial fungicide application decision support tool that takes C.
sojina population density into account for the observed and predicted frogeye
leaf spot severity that influences soybean yield. In addition, the value of
fungicides applied to susceptible and frogeye-resistant soybean varieties will be
assessed as a fungicide application decision aid.
This project will increase undergraduate student interns’ awareness of integrated
pest management. They will gain basic knowledge of plant pathology, plant
disease epidemiology, molecular biology, and statistics through this project.