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Extension Entomology

Tag: green clover worm

Soybean Update – Green cloverworms and Stink bugs

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Green cloverworm adults are quite numerous and are laying eggs in alfalfa and soybeans.  So, there are, or will soon be, small larvae present.  Feeding by green cloverworms will probably not impact alfalfa or most soybean fields unless there are significant larval populations in really late planted fields.

 

 

Stink bug populations seem to be increasing in north central Kansas but most beans should be far enough along in their development that stink bugs should be of little concern.

 

For management decisions for all soybean pests, please refer to the 2017 Soybean Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF743.pdf

Soybean Pests Update

–by Dr. Jeff Whitworth, Dr. Holly Schwarting and J.R. Ewing

Green cloverworms have moved into the pupal stage, for the most part, and thus have finished feeding on leaves.  There will probably be another generation of green cloverworms so any late planted soybeans may be at risk for defoliation again although it probably not enough to warrant an insecticide application.  Adult bean leaf beetles and stink bugs may also still be present in soybean fields and feeding on beans as long as they are still filling inside the pods, so monitoring should continue until pods are mature.

Soybean Pests Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Green cloverworm larvae have been rapidly increasing all throughout the eastern 2/3rds of Kansas.  These worms are very well camouflaged and usually feed on the underside of leaves, thus are not always evident until holes start showing up in leaves.

green cloverwomr larva

soybean defoliation

There has been concern relative to this leaf feeding but generally it is not until the density reaches 10-12 larvae/ row ft. with about 30% defoliation, and larvae are still small (1/2 inch or less) that an insecticide application may be justified.  However, in past years when those cloverworm densities have been achieved there has been an entomopathogenic fungus that rapidly decimates the populations.  This seems to be starting this year, as the first fungal-infected green cloverworm larvae were noticed on 23 August in several counties in Kansas.  This fungus causes the green cloverworm larvae to stop feeding after 12-24 hours of infection and causes death 24-48 hours later.  Sometimes, these infected larvae still look alive even in death, which is one of the characteristics of this fungus.  There will probably be at least one more generation of green cloverworms to come.

fungal GCWfungal GCWs

Don’t forget to continue monitoring for adult bean leaf beetles, stink bugs, and podworms, all of which may feed on pods and/or seeds.  There will probably be one more generation of podworms this year.  For more information on soybean pests please see Soybean Insect Management 2016, available here: https://www.bookstore.ksre.ksu.edu/pubs/MF743.pdf

 

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