Excess mixture is the diluted pesticide that is leftover in your spray tank after a pesticide application. Whenever possible, excess spray mixture should be applied to a crop or site permitted by the label. Do not exceed the labeled application rate, and follow all directions.
Excess spray mixture should not be stored in the spray tank. If environmental conditions are not conducive for immediate application on another registered site, maintain periodic or continuous agitation as recommended on the label, so that the pesticide does not settle in the tank.
If you cannot use the excess mixture per label directions, you must decide its waste classification before disposal. Some pesticide-containing mixtures can be disposed of directly through sewage-treatment facilities. However, this depends on the specific product and the specific facility. Therefore, the applicator must notify local authorities to obtain permission. Permits may be required. Other pesticide-containing mixtures may be regulated as wastewaters, solids, or hazardous wastes (see The Law on Pesticide Wastes)
See Reduce the Need for Disposal for ideas on how to minimize excess mixture.
Excess Water after use in packinghouses or greenhouses: In certain packinghouse or greenhouse situations, pesticide mixtures are included in the treatment regimen. As in other situations, it is important to minimize the amount of mixture created so there is little to no excess remaining and, if a pesticide-containing mixture cannot be used in accordance with label directions, the applicator must evaluate its waste classification before disposal.
Some pesticide-containing mixtures (e.g., from packinghouse dump tanks) can be disposed of directly through sewage treatment facilities. However, this depends on the specific facility and therefore requires that local authorities are notified and permission obtained. Permits may be required. Other pesticide-containing mixtures may be regulated as wastewaters, solids, or hazardous wastes (see The Law on Pesticide Wastes). Many states regulate the various wastes from packinghouses through other agencies in the state government. Here are headquartered, regional, and state contacts for NPDES wastewater disposal.