Project Overview

Reports

Commodities

• Agronomic: soybeans

Target Pests

• Target Pests: fungus, other

Practices

• Pest Management: host resistance

Aerial blight is a major yield-limiting disease of soybean in the mid-South. Favorable weather conditions and cropping practices make the causal agent – Rhizoctonia solani AG1-IA, a soil borne fungus – thrive in the tristate area of Arkansas, Louisiana, and Mississippi, and in 2020 resulted in $12 million estimated losses. The pathogen is impossible to eradicate once established in the field and requires effective management tools to ensure the profitability of soybean. In Louisiana, the pathogen population is known to have evolved resistance to the commonly used fungicides, and fungicides with alternate modes-of action may be necessary for control. These alternate fungicide chemistries, however, are very specific in their activity, and development of fungicide resistance is inevitable. Thus, to support growers in Louisiana and the mid-South tackle aerial blight, there is an urgent need to develop other tools that can be used in an integrated disease management approach.  

A core component of integrated disease management, host resistance, is currently underutilized against aerial blight. There is little information on whether commercially available soybean cultivars can resist R. solani AG 1-IA. This is partly because field rating for aerial blight (in germplasm screenings) is difficult due to the patchy distribution of the pathogen in the field. Thus, although variety trials conducted across Louisiana indicates susceptibility of cultivars to aerial blight, cultivars that escape disease may appear resistant. To address this knowledge gap, we have developed a greenhouse cultivar screening protocol. The protocol is relatively quick, reproducible, and provides a gradation of symptoms in susceptible and resistant checks. The present proposal aims to use this protocol to screen commercial cultivars, to test the feasibility of using host resistance to manage aerial blight. The project will also include publicly available cultivars (Plant Introductions, PIs) in the screening to lay the foundation for studies on the mechanisms of host resistance to aerial blight. The first objective of the proposal is thus to screen commercial soybean cultivars and PIs for resistance to aerial blight to develop short and long-term tools to manage the disease.

To develop regional solutions for aerial blight management, building collaborative projects involving all relevant stakeholders is key. As a first step towards this, we will develop research and extension publications on aerial blight and its management, and present our findings to stakeholders and the scientific community. Through these discussions with new and existing collaborators we will develop regionally collaborative projects to address various aspects of aerial blight management. The second objective of the proposal is thus to communicate research findings to growers and scientific community and develop larger collaborative projects on aerial blight management.

The current project requests seed funding to develop host resistance as a management tool against aerial blight of soybean. Since soybean varieties change annually, screening commercial soybean cultivars will provide only short-term (though much needed) solutions. For long-lasting solutions, there is a need to generate information useful for breeding for resistance and develop collaborative projects that tackle aerial blight more holistically. This seed project will thus generate foundational tools to study aerial blight, add well-trained students to the plant pathology workforce, and pave the way for new collaborative projects to address field crop diseases in the Southern United States.