A website from UGA Cooperative Extension

Southern Corn Rust Confirmed – 6/9/21

Southern corn rust (SCR) has been confirmed in Coffee County as of Wednesday of this week, and yesterday in Colquitt County. Updates can be checked at: https://corn.ipmpipe.org/southerncornrust/. Following is current information from Dr. Bob Kemerait:

Which growers are at highest risk?  Because the rust (which was well established in the field) was found in Coffee County, I would say any corn in the southern Coastal Plain part of the state is at risk.

Should a grower spray?  If corn has not reached VT tassel or is at R6 hard dough, do not spray. If the field has been sprayed in the last 2 weeks, don’t spray. If the field is being SCOUTED and no southern rust is found, I wouldn’t spray.

I would recommend spraying if: 1) at tassel stage or beyond, 2) irrigated with high yield potential, 3) rust has been confirmed in the area, AND 4) field is not carefully scouted. Weather is favorable for spread of SCR and we have beaucoup corn this year in the state.

What to spray?  Single mode of action products like tebuconazole, tetraconazole, azoxystrobin and pyraclostrobin are good products for about 2 weeks or so.  Mixed mode of action products are better and last longer. Are there “best” products?  Yes, but NOTHING works once rust is well established in a field of corn.

Peanut Disease Update – Kemerait

Much of our peanut crop is approaching (or has reached) 30 days after planting.  30-45 days after planting is CRITICAL for initiating a fungicide program, especially now. Whether you start at 30 days or wait until 45 days after planting depends on:

1. Peanut Rx Risk Index scores, especially variety and rotation factors

2. What products you will spray first (some need to be sprayed at 30, some can wait until 45)

3. Whether or not Velum was used in furrow

Given that conditions are favorable, it wouldn’t hurt to include something early-season for white mold control, though most major white mold programs begin at 60 days. PLEASE! Do not wait beyond 45 days to begin your fungicide program; growers who wait beyond that may be playing “catch up” for the rest of the season. The Peanut Rx 2021 can be found at: https://peanutrx.org.

Soybean Disease Update

We know soybean rust is active now in kudzu across southern Georgia. That is the “spark”.  This weather is like “gasoline” to that spark, so I expect soybean rust to spread further in kudzu and eventually to soybeans.  Soybean growers will need to be prepared to protect their soybeans when the beans start to bloom. Check for updates on soybean rust at: https://soybean.ipmpipe.org/soybeanrust/.