Registrants include Chemtura Corp., DuPont, Glades Formulation Co., Rotam Ltd. and Sinon Corp.
The measures will cancel the use of methomyl on barley, oats, and rye and restrict its use on wheat to Idaho, Oregon and Washington, according to a release.
In celery, head lettuce and peppers, the number of applications will be reduced by 20 percent and the seasonal maximum rate will be reduced by 12 percent to 20 percent.
The number of applications for leaf lettuce, field corn, popcorn and seed corn will be reduced 25 percent to 50 percent.
Although Florida and California area the greatest areas of concern for drinking water, the registrants have agreed to implement the measures nationwide.
Methomyl, a carbamate, is a restricted-use broad-spectrum insecticide. Among its brand names are Lannate, Lanox, Methavin and Nudrin, according to Cornell University.