Because of this, it is imperative to study the many aspects of various diseases affecting the crop in Delaware and throughout the mid-Atlantic region.
Such work requires a collaborative effort and a team has been assembled thanks to a five-year, $1.5 million U.S. Department of Agriculture (USDA) Specialty Crop Research Initiative grant.
The grant awarded to the University of Delaware includes researchers from UD, Delaware State University, the University of Maryland, Ohio State University, Cornell University and the University of California Davis (UC Davis) who will begin studying the various effects of plant disease on lima beans in the First State.
The many aspects of this grant will include studies that are being conducted for the first time in history.
There are six components to the grant, each with various researchers studying different parts of the problem. They are conducting research on downy mildew, pod blight, white mold, root knot nematodes and germplasm resources and developing an economic analysis.
Downy mildew is a fungal-like disease of the lima bean caused by Phytophthora phaseoliand the goal of the research team is to improve disease forecasting and look at genetic diversity of the population of the pathogen. In this way, researchers will be able to inform farmers of their risk of occurrence of the disease and have a better understanding of the genetics of the pathogen.
Tom Evans and Nicole Donofrio, professors of plant pathology in the Department of Plant and Soil Sciences in UD’s College of Agriculture and Natural Resources, and Nancy Gregory, plant diagnostician for UD, will work together on this part of the project.
Pod blight is caused by the pathogen known as P. capsici and Gordon Johnson, assistant professor of plant and soil sciences at UD, will work on this part of the study with Evans and Gregory.
Unlike downy mildew, which is a disease that generally affects only lima beans, P. capsicihas a very wide host range. Once it strikes a particular crop, it is very difficult to get rid of, with pathogen’s spores lasting up to 10 years in the soil. Because of this, pod blight is an increasing problem for growers. The disease occurs in low-lying areas of fields and is more frequent in wet years. Therefore, this part of the project has three goals: to look for a fungicide to deal with the disease, to monitor the disease, and to look for alternative or organic non-pesticide driven strategies for control.
The study is also looking at risk management strategies, including information for growers in the state about the best time to spray for disease control and consideration of alternate control strategies.
Gregory, who diagnoses field samples collected by the research team and growers, maintains cultures of the pathogens and produces the inoculum for the studies, said that the researchers are eager to “learn more about the epidemiology and the spread of pod blight and downy mildew, that will enable us to do a little bit better job on forecasting.”
She also noted how great is to have so many expert researchers involved, noting that she is looking forward to making significant progress on problems that have plagued the region for years. “To pull together a strong team of researchers like this and many new graduate students is really going to pull a lot of this research together and we’ll really come up with some great results.”
Kate Everts, an adjunct associate professor of plant and soil sciences at UD and a Cooperative Extension specialist with both UD and the University of Maryland, is leading research on alternative ways to control white mold, another disease that is very difficult to eliminate.
With an even broader host range than P. capsici, and an even longer life — persisting in soils for 20-30 years — finding out as much about the disease as possible, as well as possible ways to control it, is imperative.
Everts will look not just at lima beans but other crops, as well, as she tests biological control strategies and alternative control strategies for dealing with the white mold.