Treatments at cultivation time are sometimes delayed in wet fields, allowing severe root damage to occur before insecticides can be applied. The delay may extend beyond the time that effective soil treatments could be applied. Granular formulations of insecticides are usually preferred over liquid formulations for controlling rootworm larvae, because of their better effectiveness and safety. When Applied at Planting Many factors will reduce control of larvae, especially if the insecticide is applied at planting before May 15. Prolonged dry conditions of soil may limit chemical release.
Alkaline soils cause insecticides to deteriorate faster than neutral or slightly acid soils.
High populations of microorganisms may accelerate breakdown of some insecticides in certain soils. High soil organic matter content may reduce efficacy. Control with most insecticides will be reduced if they are applied in narrow bands, if granules are not covered with soil, or if wind blows granules off the rows. Application is less than the labeled or suggested rates. All of these factors are of greater importance with early planted corn.