Today we received an update from Dr. Bob Kemerait about crop disease and favorable weather conditions. In his email he stressed that the current weather conditions (including the possibility of a tropical system in the gulf) , warm temperatures and high humidity, are favorable for the spread of fungal diseases.
Note for Soybean growers… Asian Soybean Rust has been found on new growth in Miller county. It is hard to determine the source of the infection but it may be linked to spores from an overwintering source in Miller county. Scouting your fields is a must in our southern subtropical climate where the weather stays favorable for so many diseases.
Note for Corn growers…Common rust has been found in many fields, including some in Randolph, Calhoun, and Terrell counties. Dr. Kemerait noted that this disease didn’t concern him as it doesn’t do much to hurt our yield. On the other hand Southern corn rust, which has more potential for yield loss, has not been found in Georgia this season. Northern corn leaf blight is present in some fields in our area but has not gotten to destructive levels as of yet. Keep in mind that this disease can be aggressive and current weather conditions favor the spread of this disease.
The movement of a tropical depression and associated rainfall could impact row crops and diseases in at least 4 ways.
1. Moisture (rainfall and humidity) will create perfect conditions for the development and spread of fungal diseases. as our corn crop and our peanut crops continue to grow, there is increased chance that the leaf-wetness period will increase within the canopy of leaves. Long leaf-wetness periods coupled with greater humidity creates a paradise for fungal spores- more infection, more growth, more spore production, more disease.
2. The movement of leaves within a storm helps to further spread the spores from infected leaves to new leaves. The force of raindrops spreads spores from infected leaves and also from soil debris.
3. The movement of storms from the Gulf of Mexico to Georgia may also mark the movement of rust spores (soybean rust and southern corn rust) from the Caribbean and Florida to Georgia.
4. Rainfall will cool soils and help to reduce impact of Aspergilllus crown rot in peanut.
So whot does this mean?
1) Growers should be aware that the conditions for the next few days will be more favorable for disease.
2) If growers were planning on making a fungicide application in the next few days, it will be better to be ahead of the storm.
3) This does not mean that every grower needs to be spraying a fungicide now, but growers should keep their eyes open after the storm for any diseases that may develop.
Jay, Nick and I will keep posting updates about disease and other pests as the season continues.