Row Crop Disease Update
Corn: Southern corn rust has been confirmed in Coffee County. The extended period of wet weather we had a week ago helped to bring on rust. Even though there is currently not a lot of rust to be found, this could change quickly with our recent passing storms and high humidity.
Although rust has been found, do not panic. Corn already into dough/dent stages should not need to be sprayed for rust. Corn in late milk stage is likely safe as well. Corn at early milk, pollination/silking, and tassel is likely at risk. Tebuconazole is a “good” rust material with a protective window of about 2 weeks. Domark (tetraconazole) is also a good-single mode of action product. The mixed mode of action products like Aproach Prima, Headline AMP, Priaxor, Stratego YLD, and Trivapro, have a longer protective window (3 weeks or so) and likely broader-spectrum activity. If you are going to spray a fungicide, sooner is better. The more disease that gets established in a field, the harder it is to control.
Keep in mind that even if you don’t spray, you may not have a problem with rust, but should a grower gamble on that? Deciding on spraying a more-expensive fungicide or a less-expensive fungicide can be tough. Two things to consider: 1) How are your yields looking? How much do you want to protect it? 2) What growth stage is your corn, the older the corn, the less risk to disease.
Irrigated corn in the silking/pollination stage needs spraying. Dryland corn in the same growth stage would only need spraying if yields can realistically and economically cover the cost of fungicide treatment.
Soybeans: Asian soybean rust is present in kudzu across the Coastal Plain. Conditions (windy and passing storms) are perfect for moving it to soybeans. Applying a fungicide at the R3 stage is highly recommended.
Peanuts: We are in perfect conditions for development of white mold. Across the state there are reports of white mold in all ages of peanuts. Very warm soil temperatures followed by moisture and now by hot temperatures create the most ideal white mold conditions. Stay timely with fungicides.
Cotton: No target spot or areolate mildew has been found, but conditions are favorable. First bloom is an important time to check your crop for target spot. Even if you don’t spray, be aware. Also, keep your eyes open for reddened, stunted, distorted plants that COULD be our new viral disease. If you find plants like that, please let me know so we can check them out.