South Carolina Soybean Rust Update – 7/21

July 21, 2023


21 July 2023

FROM:  Jonathan Croft, Clemson Extension Agronomic Agent, Joe Varn, Clemson Extension Agronomic Agent, Rogan Gibson, Clemson Extension Agronomic Agent, and Dr. John Mueller, Extension Soybean Pathologist, Edisto Research and Education Center.

This is the first weekly Soybean Rust News Note for the 2023 growing season.  At this time, Asian Soybean Rust has NOT been identified in South Carolina.

We began sampling soybeans in the Savannah Valley region this week.  Maturity group four soybeans have set and are filling pods, and early planted maturity group seven soybeans have just begun to flower.  There are a lot of later planted beans that are still in the early to mid-vegetative stages at this time.

Downy mildew was observed while sampling and our current weather patterns are conducive for Downy mildew development; however, yield losses to downy mildew are typically minimal, and no fungicide applications are recommended.

If you would like information on foliar diseases of soybeans in SC, see our Land Grant Press publication “Identifying and Managing Foliar Fungal Diseases of Soybean”

If you think you have rust or other foliar diseases in a field, collect 25 to 50 of the leaves you are “suspicious” of.  Place them in a “ziplock” type bag.  Keep the bag out of direct sunlight and in a cool place if possible.  Do not allow it to freeze or get close to freezing.  Contact your local county agronomic agent for evaluation.