Insecticides for Plant Bugs

With cotton squaring and flowering weeks away, it is a good idea to think about treatment options for plant bugs.  Generally the neonicotinoid-class insecticides perform well early in the season before flowering and often at lower rates.  These include products such as Admire Pro, Belay, Centric, Intruder, Trimax Pro, etc.  The advantage to using these products is that they generally do not flare secondary pests, such as spider mites, and may preserve some, but not all, beneficial insects.  In general, a product that is killing a plant bug will likely kill related beneficial insects such as minute pirate bug and insidious flower bug, damsel bugs, assassin bugs, and big-eyed bugs.  However, these products are still much less harsh on the system than pyrethroid and organophosphate-class insecticides.

Cumulative plant bugs per row foot 14 days after treatment.

Cumulative plant bugs per row foot 14 days after treatment.

Later on in the season, neonicotinoid insecticides generally do not work as well.  However, Belay seemed to performed in a plant bug trial during 2010.  That being said, I am recommending that you do not spray a pure neonicotinoid product more than once a season (common examples of Admire Pro, Belay, Centric, Intruder, Trimax Pro are listed above) or a mixed product more than twice a season (common examples include Brigadier, Endigo, and Leverage 360).  Aphid resistance to neonicotinoids is on the rise and was confirmed in Eastern NC in 2012.  All cotton seed treatments targeting thrips are neonicotinoids and pre-mixed product use in cotton is widespread.  Hence, the increase in neonicotinoids in cotton is increasing aphid resistance to these products.  Therefore, to counteract this resistance I am recommending that you rotate insecticides.

Here is an example of a spray plan.  Of course, before any spray, you should have scouted the field and exceeded the recommended threshold for spraying.  Consult this article by Jack Bacheler for scouting information and an update on what this year might have in store for plant bugs.  For the first plant bug spray pre-bloom, at squaring or first flower, consider using a stand-alone neonicotinoid product (common examples include Admire Pro, Belay, Centric, Intruder, Trimax Pro).  If plant bugs are still a concern later on, or require a second spray, first check to see that aphids are not common in the field.  If they are, you should not use a neonicotinoid again.  Switch to a product like Carbine or Transform.  Remember that aphids first occur in field “hot-spots”.  So you might not see a population and resistance developing until it is full-blown.  Be sure to scout these fields intensively.  If aphids are not a concern, you should still not use a stand-alone neonicotinoid product for a second spray, but should switch to one of the pre-mixed products or an organophosphate/carbamate-only product (e.g., Bidrin, Orthene or Vydate).  Many of these products are also effective against stink bugs; eliminating stink bugs can be beneficial during the period of boll formation.  The downside to these products is that they kill beneficial insects and put you at risk for bollworm and spider mites.

If you end up spraying plant bugs this year, will this article influence your use of insecticides in any way?

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