Principle Investigator: Carl Bradley

National Research Service/National Institute of Food and Agriculture

Plant diseases are considered one of the most important yield-limiting factors in the production of soybean and small grain crops (i.e., barley, rye, and wheat) in Kentucky and the surrounding regions of the United States. Diseases annually reduced Kentucky soybean yields by an estimated 7.26% and reduced soybean yields across the entire United States by an estimated 8.74% from 2015 to 2019. Top yield-limiting diseases that contributed to these losses that affect Kentucky soybean farmers include charcoal rot, Diaporthe seed decay, frogeye leaf spot, Phytophthora root rot, root-knot nematode, seedling diseases, Septoria brown spot, soybean cyst nematode, stem canker, and sudden death syndrome. Diseases annually reduced Kentucky wheat yields by an estimated 1.61% and reduced wheat diseases annually across the entire United States by an estimated 7.49% from 2018 to 2022. Important yield-limiting diseases that contributed to these losses that affect Kentucky wheat farmers include Fusarium head blight, Septoria leaf blotch, Stagonospora leaf blotch, rust diseases, and viral diseases.

The goal of this research is to minimize the negative effect of diseases on soybean and small grain crops grown in Kentucky. The objectives are to: i) develop effective management strategies for important diseases of soybean and small grain crops; ii) establish fungicide resistance monitoring programs for important fungal pathogens of soybean and small grain crops in Kentucky; and iii) monitor for new pathogens and new variants of pathogens of soybean and small grain crops in Kentucky.

The target audience includes farmers, crop consultants, university extension personnel, industry representatives, government agencies, commodity board representatives, and others working in agriculture and plant pathology. The activities described in this project will result in the research and development of practices that will improve disease management.

Disease management practices often utilized by Kentucky farmers to mitigate losses include planting cultivars with genetic resistance to specific diseases, rotating with non-host crops, and applying chemical crop protectants (fungicides and nematicides). In some cases, intensive use of specific host resistance genes and fungicides have led to high selection pressures on pathogen populations. These pressures have sometimes led to the selection of strains of pathogens that may be less-affected by specific resistant genes (selection of virulent races) or by specific fungicide active ingredients (selection of fungicide-resistant strains). Changes in pathogen populations can lead to a level of complexity when farmers are implementing disease management plans. Therefore, it is important that new sustainable disease management practices and technologies be developed to limit losses caused by ever-changing pathogen populations. It is also important that pathogen populations are periodically monitored for their sensitivity to current disease management practices.