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How Clethodim to Injure Corn? (06/22/17)

Question: A grower sprayed glyphosate plus clethodim (select) on his soybean to kill weeds and volunteer corn. The grower did not clean the tank after the last load and filled the next tank with just glyphosate to spray his RR corn. The results looked like the photo to the right. Can there be enough clethodim in the spray system from the previous load to cause this injury?

How Clethodim to Injure Corn?

Question: A grower sprayed glyphosate plus clethodim (select) on his soybean to kill weeds and volunteer corn. The grower did not clean the tank after the last load and filled the next tank with just glyphosate to spray his RR corn. The results looked like the photo to the right. Can there be enough clethodim in the spray system from the previous load to cause this injury?

Answer: Yes, the clethodim residue in the tank can cause corn injury. The symptoms in the photo are classic Group 1/ACCase inhibitor herbicide symptoms. Chlorotic leaves and even white spots appear on new growth. A very low dose, the concentration from lack of sprayer cleanout, can cause these symptoms. Full phytotoxicity will take 10 to 14 days. I cannot determine if the plants will recover or remain stunted and result in possible stand loss from death. It may take up to 14 to 21 days to determine the end result.

 Zollinger.2

Rich Zollinger

Extension Weed Specialist

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