Insecticide Efficacy for Corn Earworm, Beet Armyworm and Looper in Soybean

This experiment was applied on 13 August, in Tyrrell County soybean.  It was sprayed using a Hi-boy at 12.5 gallons to the acre.  Lepidopteran pests present included corn earworm, beet armyworm and soybean looper.  Contrast these results with those for corn earworm in 2011 (click here) and 2010 (click here) and for loopers in 2010 (click here).

For corn earworm at this location, pyrethroids were working well (Baythroid and Tombstone). This will not be the case in every location (see this post). The addition of chlorantraniliprole (Besiege- not registered in soybeans, but registered in corn and cotton) and Bt (Dipel) was not needed for pyrethroids to be effective. Dipel was also not needed for efficacy on corn earworm in 2011.  Some chemistries other than pyrethroids worked well, such as chlorantraniliprole (Prevathon- not registered in soybeans, but registered in cotton. Release expected in 2013) flubendiamide (Belt), and indoxacard (Steward).

Chemicals including chlorantraniliprole (Besiege and Prevathon), flubendiamide (Belt), and indoxacard (Steward) worked well. Although results from tests across the Southeast and Midsouth show that methoxyfenozide (Intrepid) works well, it did not control beet armyworm well in this experiment.  It can be applied up to 16 oz/A and 8 oz/A is the highest recommended rate on the label for beet armyworm.  Therefore, Intrepid may work better at these higher rates.  Pyrethroids are not effective for managing beet armyworm.

Indoxacard (Steward) was the best insecticide for soybean looper. This is consistent with results from 2010. Results from chemicals including chlorantraniliprole (Besiege and Prevathon) were mixed. Pyrethroids have some efficacy on soybean looper, but will not control them alone.  Often times a pyrethroid will flare looper populations by killing natural enemies that may have eaten them.  Regardless, the addition of a pyrethroid to Prevathon seemed to help. Flubendiamide (Belt) worked well, albeit at higher rates, consistent with results from 2010.  The recommended labeled rates for methoxyfenozide (Intrepid) and loopers are higher (10-16 oz/A) than those that were tested in this experiment (4-6 oz/A).  It is likely that this chemical would have worked better at higher rates. The addition of Dipel to a pyrethroid did not improve soybean looper control.

 

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Insecticide Efficacy for Corn Earworm, Beet Armyworm and Looper in Soybean — 4 Comments

  1. Would have been interesting to have seen Tracer @ 1.5 oz tankmixed with a pyrethroid, and Tracer @ 2 oz in this trial for lep efficacy.

    Will there be a A 7 day post treatment efficacy rating?

    • Check the links in the above article for the 2010 data. Tracer looks good at 2 oz. and is part of our recommendations. Not a lot of folks spraying it, however.

  2. Field observations on looper control with Intrepid @ 6 oz indicate very gfod control. Intrepid, of course is a molt acclerator and works via injestion. Sometimes, three day control observations will detect what are called “dead worms walking”…….loopers that have quit feeding and are undergoing premature molting, then mortality. Intrepid gives realistic resdiual activity of up to 10 days and symptoms can be deteced in loopers up to 14 days post
    treatment. Given the mode of action for Intrepid, 5-7 days post treatment evaluations usualy are the best way to measure the overall performance. The 6 ounce rate has proven to be a robust field proven rate that is competitive and economical.

    Tracer is an excellent option tank mixed with a pyrethroid @ 1.5 oz or stand alone @ 2 oz where pyrethroid resistant corm earworm or budworm are in the mix. Tracer has displayed effective soybena looper control as well.

    Both Intrepid and Tracer are in good supply and readily available at ag-chem retailers across North Carolina.

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