Watch Out for Tar Spot

Fungus is just starting in fields and scouting right now is extremely important. The hot button for the last couple of years has been tar spot and currently we have not seen any in Marion County. The conditions for fungal growth have been there with all this moisture and heat, so we expect the disease to show up.

Tar spot has a three-week latency period, meaning once infected we won’t see symptoms for three weeks. Generally, once you see the tar spot symptoms, effective control is too late. The big question is when will tar spot show up this year? If tar spot shows up late, like last year, we don’t see a lot of yield reductions, but it will still increase the severity in the coming year.

Tar Spot overwinters on corn stalks so if you had the disease last year you will likely see it again this year. With the condition of the crop, I still recommend spraying fungicide on highly producing fields. Even in a low commodity market fungicide can give you the 10+ bushel needed to pay for the application and provide greater stay green and better standability.

When commodity prices are low, we don’t necessarily spray every acre with fungicide but even with cheaper corn we can still find places to have a good ROI. Reach out to your SFG Agronomist and discuss if there are places on your farm that may benefit from a fungicide application.