[Image: Pesticide]Farmers rarely use all the pesticides they buy in a given season. Often the question arises the next spring as to whether the chemicals are still useable. With a few simple precautions, pesticide quality can be easily maintained in storage during the winter.
Proper storage begins with having storage facilities that are well-ventilated, dry and lockable. Proper warning signs must be clearly visible. Pesticides should be stored separately from seed, fertilizers, and potting media, since these materials can absorb volatiles from the pesticides. Always read the pesticide label for information on storage and handling. Before storing, check pesticide containers for cracks, tears, or leaks and make sure they are securely sealed.
Dry pesticides such as wettable powders, dry flowables, and granules are not affected by cold or freezing temperatures. They need to be kept dry because moisture can cause caking and breakdown of the materials. When storing dry and liquid products in the same area, the dry materials should be stored above the liquid materials to prevent problems in case the containers of liquid should leak.
Liquid formulations vary in response to cold temperatures. For example, freezing does not damage Roundup, but can reduce the effectiveness of Gramoxone. Freezing can cause the pesticide container to burst. Low temperatures often cause the emulsifiers to separate from the active ingredient, leading to crystallization or coagulation of the active ingredient.
In the spring before using the pesticides, always check their condition. Thoroughly break up caked portions of dry materials. Liquid products that have separated, crystallized, or coagulated should be placed in a warm area (60EF or above) for several days and shaken or stirred periodically during that time. The warm temperature and agitation should re-mix the product. Do not apply heat directly to the container. If the solution does not re-dissolve, it probably should not be used.
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