Tarnished Plant Bug Update

Angus Catchot, Extension Entomologist
By Angus Catchot, Extension Entomologist and Jeff Gore, Research and Extension Entomologist June 23, 2012 08:44

This week has been the turning point on plant bugs and appears to be the week for the mass movement of migrating adults into cotton fields in many areas. Compared to previous years we are 10-14 days behind schedule. There have been quite a few sprays going out for tarnished plant bug this year but as a whole numbers have actually not been as high to date as many of us would have thought with the warm winter. However, I believe we are on track to have about the same number of sprays as usual in the Delta region but instead of treating 3-4 X threshold numbers we are treating just threshold numbers in many locations so far.

This year we could find nymphs in henbit as early as January which pointed to at least one, possibly two extra generations this spring for big numbers to move into our crops. So what happened? We went through several droughty periods early in the Delta that was not good for the wild hosts that plant bugs build on prior to moving into the crops. That is why it will always be difficult for entomologist to predict what bug numbers will be based on winter conditions.  In fact, it is more about the spring then the winter often times.

I have had three calls this week about low square retention and no plant bugs can be found in the field. Admittedly, there is not many things that cause squares to fall off of a plant outside of insects, but this four bract square phenomena we have been dealing with the last couple of years is definitely one of them that will.  It is frustrating if you are a consultant because it is blamed on plant bugs a lot of the time when it has nothing to do with bugs (see Darrin Dodds article on four bract squares).  If square retention is low and no plant bugs can be found, be sure and check for the presence of four bract squares.

So moving forward here are a couple of things to think about. Tank mixes or premixes have performed much better than single products in the Delta. In the Hill region of the state, single products are still preforming well. The addition of a pyrethroid can definitely improve the control you will get with organophosphates and carbamates. Try not use the same mode of action every week, break the cycle. Remember that when you are dealing with migrating adult plant bugs, finding the same numbers or higher 4 days after application does not necessarily mean you have had a failure, it could very well be new bugs moving into the field. It will be necessary to use square retention counts to judge how your applications are working. Remember, things can change rapidly.

 

 

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Angus Catchot, Extension Entomologist
By Angus Catchot, Extension Entomologist and Jeff Gore, Research and Extension Entomologist June 23, 2012 08:44
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