The extended period of wet weather a week or so ago helped to bring on rust after it was much delayed this year. All corn across the southern Coastal Plain is currently at risk for infection. We cannot find a lot of rust right now, but that could change quickly with our recent passing storms and high humidity.
Southern corn rust is still at low levels, so don’t panic. Corn already into the dough/dent stages should not require a fungicide for rust. Corn in late milk stage is likely safe, as well.
However, corn at early milk, pollination/silking, and tassel is likely at risk. That would be my opinion if it was my corn.
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. Premix products have a longer protective window (3 weeks or so) and should provide broader-spectrum activity. These include, but aren’t limited to, Approach Prima, Headline AMP, Priaxor, Stratego YLD and Trivapro.
If growers intend to spray a fungicide, sooner is better. The more disease in a field, the harder it is to control.
AgFax Weed Solutions
Even if a grower doesn’t spray, he may not have a problem with rust. But does he want to gamble on that?
Deciding on spraying a more expensive fungicide or a less expensive fungicide can be tough. Two things to consider:
- How are your yields looking and how much of that potential do you want to protect?
- What growth stage is your corn. The older the corn, the less risk to disease.
As of today (6/25), southern corn rust is confirmed in these counties: Early, Laurens, Dooly, Atkinson, Coffee and Baker.
Again, though, it could be anywhere on the Coastal Plain of Georgia and is likely building.