Guess the Pest!

Bill Cissel, Extension Agent – Integrated Pest Management;

Week #17 Guess the Pest proved to be a challenge and no one correctly identified the disease. The correct answer is tar spot. Thank you to everyone that participated in Week #17 Guess the Pest.

Click on the Guess the Pest logo below to participate in this week’s Guess the Pest! Guessing correctly will automatically enter you into a raffle for $100 gift card at the end of the season and one lucky winner will also be selected to have their name entered into the raffle five times. For Guess the Pest # 18, we will also be giving away A Farmer’s Guide To Corn Diseases ($29.95 value) to one lucky participant.

Guess the Pest Week #17 Answer:

Tar Spot on Corn
Tar spot is a relatively new disease to the United States. The disease originates from humid, mountainous regions of Central/South America and was first identified in the United States in 2015. Currently the disease has not been detected East of Indiana. Tar spot is caused by the fungus Phyllachora maydis. Symptoms start as oval to irregular brown lesions. Over time the lesions become black spots, which cannot be rubbed off like rust pustules. Lesions can expand and coalesce to form large, blighted areas of tissue. The fungus is not known to cause yield loss except when a second fungus, Monographella maydis, co-infects tissues. Luckily we have not yet observed this second fungus in the United States.

Dr. Nathan Kleczewski, Extension Plant Pathologist


Guess the Pest Week # 18

What caused this damage?

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