Jonathan Croft, Agronomic Row Crop Agent for Orangeburg county found rust in a sample of 80 soybean leaves collected today from a soybean field at the R 5.4 growth stage in the Norway area. There were 5 pustules on one leaf and 3 pustules on another leaf. The pustules are just starting to sporulate.
Rust has now been found in Colleton, Bamberg, and Orangeburg counties.
Counties that have been surveyed but no rust found now include: Allendale, Anderson, Barnwell, Calhoun, Clarendon, Dillon, Darlington, Dorchester, Hampton, Horry, Jasper, Lee, Marion, Newberry, Richland, Saluda and Sumter Counties.
I think there should be a new saying about the weather in South Carolina: “if you don’t like your weather just drive 20 or 25 miles in any direction.” Near the Edisto REC the weather has been perfect for the development of rust and many other foliar, stem and pod diseases such as Anthracnose, Phomopis and Purple Seed Stain.
Long dews and overcast, foggy weather in the morning are very favorable for disease development. However, I am told in other parts of the state we are back to clear and dry. If you have soybeans with good yield potential that are between growth stages R-3 and R-5 this would be a great time to spray before any diseases develop.
Remember, once you hit R-6 in a given field you cannot spray any fungicides.
Here are a few more survey results from the last few days:
Jonathan Croft, Orangeburg County Agronomic Row Crop Agent also collected 75 leaves from a field in Dorchester County that was at the R 5.3 stage on September 16. No rust was found.
Andrew Warner, Allendale/Hampton Agronomic Row Crop Agent collected 200 leaves on September 19 from a field in Allendale at R 4; no rust was found.
If you would like an update on the occurrence of soybean rust across the United States check out this site.