Earlier today I found Southern Corn Rust in a field in Mitchell County. What’s funny is I found the same disease in corn last year June 6th! One day earlier than last year!
Remember Southern Corn Rust is the most important disease on corn! Rain is back in the forecast for next week, which will be favorable for development of rust. Any corn that is approaching (or has passed) the tassel growth stage is worth protecting if the yield potential is there.
Here are some points last year from Dr. Kemerait;
- Southern corn rust (SCR) reduces the photosynthetic capacity of infected leaves. More importantly, a field where SCR is not controlled may develop extensive lodging problems as the stalk is cannibalized for nutrients to feed the ear.
- Dr. Dewey Lee and I agree that protecting a crop from rust though the dough stage is beneficial.
- I recommend that growers spray by tassel growth stage and then again 2-3 weeks later, depending on the product used in the first application.
- On corn where rust is a severe problem, we have seen fungicides protect 25+ bu/A.