Calculating your Spray Rate

Most pheromone trap-based guidelines have been developed primarily to make silk spray decisions for corn earworm (CEW) control. Generally, an insecticide spray is applied to green silking corn as soon as more than one moth is captured over a five day period on a farm. Repeated applications are made at 2 to 6 day intervals depending on the cumulative number of CEW moths captured and the type of trap used.

The below recommendations are for pheromone trapping using the Scentry nylon mesh trap and Hercon Heliocoverpa zea lure. For more information, and trap monitoring for other traps check the full Sweet Corn Decision Manual.

Sprays are normally discontinued when the expected final harvest is less than six days away.

Average number of CEW moths captured per trap Recommended control action or days between sprays
per day per 5 days per week
less than 0.2 less than 1 less than 1.4 spray at green silk then reassess
0.2 - 0.5 1 - 2.5 1.4 - 3.5 6
0.5 - 1 2.5 - 5 3.5 - 7 5
1 - 13 5 - 65 7 - 91 4
>13 >65 >91 3

Maryland Moth Count