Experts urge growers to monitor disease pressure before spraying corn
Corn growers are entering a key decision-making period for fungicide applications as the crop progresses through important growth stages. Experts say disease levels should be carefully evaluated before investing in treatments.
The most common recommendation for fungicide application is between the tasseling stage (VT/R1) and the milk stage (R3). This period helps protect the ear leaf, which plays a critical role in grain development and final yield.
One disease being closely watched is Southern Rust. Reports indicate that infections remain limited to southern areas and have not become a widespread concern in major corn-producing regions. Because the disease cannot survive winter conditions in most parts of the United States, spores must travel north each year. Current risk levels remain low, making immediate fungicide applications difficult to justify in many locations. Growers with later-planted corn should continue monitoring conditions, especially during periods of warm weather.
Tar Spot is another disease that is receiving attention. Early-season infections have been observed at low levels, primarily in lower crop canopies. Recent hot weather may slow disease development. However, disease pressure could increase if temperatures return to more favorable levels for fungal growth.
In addition to Southern Rust and Tar Spot, reports from Gray Leaf Spot and Northern Corn Leaf Blight have also surfaced. While these diseases are generally confined to lower leaves, growers should monitor their movement toward the ear leaf area.
Experts note that fungicide applications made too early or outside the recommended growth stages often provide limited economic benefit. Growers are encouraged to evaluate disease risk, yield goals, crop value, and application costs before making treatment decisions.
New research also suggests that drone-applied fungicides may provide disease control and yield protection comparable to, and sometimes better than traditional aerial applications. As drone technology becomes more available, growers may gain greater flexibility in managing disease threats throughout the growing season.
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