The Alabama cotton insect situation has started to pick up over the last few days. We have received several reports of grasshoppers in fields across central Alabama. Our observations and reports are that grasshoppers have reached the adult stage in some of the fields, which is a little earlier than normal, but the winter was also somewhat mild. This is important to note, because adult grasshoppers are harder to kill and are not affected by the growth regulator Dimilin. The presence of wings is the only way to identify adult grasshoppers as the immature stages do not have them. We do not have a threshold for grasshoppers. With that in mind, treatment decisions are made based on the level of risk a grower is willing to take in a given field (how many grasshoppers are out there?). In some fields, grasshoppers do not eat cotton while in others they may destroy dozens of acres. Field history can provide some indication of what may happen this year. If grasshoppers have eaten cotton in a field previously, they seem to be more likely to do so again.
Treatment Decisions
At this point, I would probably assume adults are present in
fields. That means acephate (0.67 lbs ai/A) is the go-to product. I would
also tank-mix Dimilin (2-3 oz/A) to provide residual control of nymphs
still emerging. Pyrethroids have provided poor to sporadic control of adult grasshoppers
in previous years.
If we can be of any help, please don’t hesitate to reach out
and let us know (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay
up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton
Shorts Newsletter,
Alabama Crops Report Newsletter,
and the Syngenta Pest Patrol Hotline.
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| Adult differential grasshoppers |
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| Cotton seedlings damaged by grasshoppers |
