Below are a few comments from Bob Kemerait, UGA Plant Pathologist, about the current row crop disease situation. There has been angular leaf spot observed in Colquitt County.
ANGULAR LEAF SPOT (aka bacterial blight): Angular leaf spot is a bacterial disease caused by the pathogen now known as Xanthomonas axonopodis pv. malvacearum. We have not seen a major outbreak in many years but are seeing it more frequently this year. Here are the points I want you to know:
A. The disease is caused “angular leaf spot” because the water-soaked lesions are typically defined by the veins of the cotton leaf and take on an angular appearance.
B. As the lesion develops, it can take on an appearance more like target spot (see third picture) but is typically differentiated from target spot because of a yellow halo around the spot and because the initial water-soaked lesion is still discernable in the larger lesion.
C. Angular leaf spot CAN NOT be managed with a fungicide or anything else applied to the leaf.
D. While the bacteria can be spread through moisture and splash from irrigation and rain, reducing irrigation is likely to cause more harm to the crop during hot weather than it will help manage the disease.
E. Angular leaf spot may produce rapid defoliation of the cotton crop in severe cases. However, yield losses are not reported to be catastrophic and in a worst-case-scenario may approach 10% (notes; worst-case-scenario).
F. The angular leaf spot found thus far in Georgia has been south of Tift County and west of I-75; it is currently relatively confined.
Conditions (crop growth stage, environment (hot with chance of rains)) are now PERFECT for white mold on peanut. Growers, especially those with good canopy development/closure in their fields should be aggressive in managing this disease. Again, protecting the peanut crop from white mold critical now.
Below are links to the 2015 Peanut RX
Asian Soybean Rust has not been found in Georgia to date; however conditions are no generally favorable for the disease to spread. It has been found as close as Quincy, Gadsden County, Florida. Growers in the very southern part of the state whose crop is at late bloom/early pod set may want to consider a preventative application of fungicide if they are making a trip across the field now.