The first insects I’ve seen feeding on seedling cotton this season are grasshoppers. I have spotted newly emerged grasshopper nymphs feeding on cotyledons and the first true leaves in localized areas of the South Plains. These young grasshoppers seem to be migrating in from nearby natural vegetation and weedy areas such as bar ditches.
If grasshopper numbers are high enough to threaten stand
establishment, an insecticide treatment is recommended. Many areas—especially
in the northern counties—will also need an over-the-top insecticide application
for thrips. Products like acephate and dicrotophos (Bidrin) offer some control
of grasshoppers, but their effects may not last long enough (especially if
applied at the rates recommended for thrips) to prevent damage from new
grasshoppers moving in. Therefore, it is important to keep a close eye on
fields for continued grasshopper movement and be ready to make a second
application if needed. Among all options, diamide insecticides offer the best
grasshopper control, but they’re more expensive than pyrethroids or
organophosphates. There are also products available with premixes of two or
more insecticides, such as acephate + bifenthrin (e.g., Acenthrin), which
provide control against both thrips and grasshoppers.
Besides grasshoppers, I’ve also seen chewing damage on
cotyledon-stage cotton caused by Blapstinus darkling beetles and flea beetles
in a few areas. This kind of insect feeding damage is more noticeable in fields
planted without insecticide seed treatments. While minor cotyledon feeding
usually isn’t a major concern, the damage becomes more serious when Blapstinus
beetles chew on the stems—potentially knocking the seedlings loose.
Blapstinus beetles are the adult form of the false wireworm,
a common pest across the South Plains. While there are no rescue treatments for
the larvae (wireworms), adult beetle activity that threatens stand
establishment may justify a pyrethroid spray.
Click here for the fact sheet on grasshoppers and their control
