LSU AgCenter plant pathologists are working on a number of projects to help Louisiana farmers make better disease management decisions.

Zhi-Yuan Chen, AgCenter plant pathologist, has been working to find new ways to control soybean rust. He and his graduate students are comparing differences in soybean gene expression levels between a pair of soybean breeding lines — one that is resistant to rust and one that is susceptible to the disease.

“We found about 20 genes that could be involved in soybean resistance to rust and are trying to ‘turn off’ each of them individually to see which one is important for plant resistance to rust,” Chen said.

One of his students has also found three new genes in the rust pathogen that can be manipulated to slow rust disease development on infected soybean leaves, Chen said.

AgCenter scientists continue to focus on Cercospora leaf blight — a disease caused by a fungal pathogen called C. kikuchii — which for years has been a major concern for soybean producers. No fungicides effectively control the disease and no resistant soybean varieties are available.

Chen and his students have been searching for a more effective way to control Cercospora leaf blight. One of Chen’s students recently discovered a gene in that pathogen that can help regulate the level of cercosporin, the toxin produced in infected soybean plants that causes diseases symptoms.

“Our lab is now looking for a way to suppress toxin production by the pathogen in infected soybean plants,” Chen said.

Plant pathologist Clayton Hollier is studying how both fungicides and cultural practices can be used to reduce the impact of Cercospora leaf blight and frogeye leaf spot on crop yield and quality.

“Cercospora blight does not react to fungicide use consistently, so I began to incorporate the use of cultural practices, especially plowing to bury crop residue,” Hollier said. “If it works, the plan is to reduce the amount of initial inoculum from crop residue available for attacking next year’s crop.”

Hollier is also working on a project that involves scouting fields around Louisiana to determine the presence of major soybean diseases and their severity. That information is sent to AgCenter extension personnel, agricultural consultants and producers so they can make informed management decisions.

Plant pathologist Trey Price is conducting trials as part of several ongoing projects at the AgCenter’s research stations in Alexandria, Winnsboro and St. Joseph as well as on producers’ farms. He is evaluating crop hybrids and varieties in the AgCenter Official Variety Trial program for resistance to naturally occurring plant pathogens in Louisiana.

Price is also evaluating commercially available and experimental fungicides — including seed, in-furrow and foliar treatments — to find the best options for disease management in Louisiana’s field crop production.

He is quantifying yield and quality losses caused by disease, determining when and if fungicide applications are necessary and monitoring pathogen populations for fungicide sensitivities.

Read about plant pathologist Ray Schneider’s research on Cercospora leaf blight on page 4. Olivia McClure