Southern Corn Rust has showed up in the last week or so and is present in at least 3 counties. It is scattered through the state and could be present anywhere. Our corn in Wilcox County is pushing to the dough stage, but no quite there.
When do we treat for Southern Rust?
UGA Extension Pathologist Dr. Bob Kemerait says corn that has reached hard dough stage and beyond is safe.
This image is of corn below Pitts yesterday. It is in the dent stage (R5) and moving toward dough stage. At this stage the kernels have a hard starch layer on the outside and a soft starch core.
When you break the cob, you can see the ‘milk’ line forming. It starts at the crown of the kernel and moves toward the base. We refer to it as, 1/4 milk line, 1/2 milk line or 3/4 milk line as it moves to the cob.
The lighter part is still milky and the darker part is turning to dough. When corn is stressed at this stage it’ll reduce starch accumulation and kernel weight.