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Earworm Spikes plus Stink Bug Complicate Management

Posted: August 14, 2012

The dramatic increase in corn earworm intensifies, and management options get complicated by stink bugs.
Earworm larvae feeding in sweet corn

Earworm larvae feeding in sweet corn

The DRAMATIC and RAPID increases in corn earworm captures that started during in early August are INCREASING FASTER now, throughout Pennsylvania and in neighboring states.  Visit www.pestwatch.psu.edu to track data from sites near your farm, developed from collaborations of Extension and PVGA.  Many sites now show greater than 11 moths per night, suggesting a 3 to 4 day spray schedule.  Multiple sites exceed 50 per night, suggesting a 2 to 3 day spray schedule.

 

Meanwhile, STINK BUGS are now moving into vegetable crops, including sweet corn. Some sites report 5 to 6 bugs per ear, from a mix of the Brown Marmorated Stink Bug and the Green Stink Bug.

 

Insecticide management gets complicated if you are dealing with both earworm and stink bugs.  Insecticides with newer modes-of-action are helpful for managing high populations of earworm – these include chlorantraniliprole (Coragen, or part of Volium Xpress), flubendiamide (Belt), and spinetroram (Radiant).  Older materials that do not rely solely on pyrethroids include Cobalt Advanced (which includes chlorpyrifos) and Lannate (which is methomyl).   Bt sweet corn that relies only on the cryIA family of genes should not be viewed as sufficient to control high earworm populations, although many fewer sprays (1 or at most 2 sprays) has worked very well in trials in Pennsylvania.

 

However, in some fields that growers relied on newer options without any pyrethroids, that’s where bug problems appeared.   The IRAC Code 28 materials (chlorantraniliprole and flubendiamide), and Bt-sweet corn, will not control stink bugs.  Pyrethroids are effective against stink bugs.  At least one premix exists (Volium Xpress) that is a premix of a newer option for earworm (chlorantraniliprole) plus a pyrethroid.

 

You may need to consider mixtures of modes-of-action to control both high earworm populations and stink bugs.  We don’t have tests of these mixtures.  Based on information from the materials alone, mixtures that include a pyrethroid (for the stink bugs) and the newer options for earworm (Coragen, or Belt, or Radiant) should work.