Growers who stocked up on fungicides for the 2005 growing season due to the threat of Asian soybean rust will likely be facing fungicide storage issues this winter, especially since it is likely that most products cannot be returned. The good news is that most fungicides have a shelf life of at least two years--and probably longer--assuming they are stored correctly. Optimum storage conditions are cool, dry conditions, away from sunlight. Storage temperatures should not go below freezing; however, if a fungicide does freeze, then slowly thaw it out at room temperature.
Read the label
Some formulations or products have special storage requirements that are printed on the label. Most liquid pesticides should not be stored at temperatures below 40 °F since low temperatures can cause the product to break down and/or the containers to break. Pesticides can separate during storage; therefore, they should be well agitated before they are added to the spray tank.
Other important points to ensure safe storage of fungicides (and all other pesticides) include:
- Store each type of pesticide on a separate shelf or in a separate area. That is, herbicides should be stored away from insecticides; both should be stored away from fungicides.
- Keep pesticides in their original packaging. Make sure the caps are tightened and that the containers are not cracked or leaking. Dispose of damaged containers according to the label recommendations.
- Place opened containers in clear plastic bags or see-through plastic containers. This will allow for easy identification of products and also will contain leaks and help avoid accidental spills
- Make sure that the original pesticide label is readable and attached to the product container. Do not store products with lost or illegible labels.
- Write down the date of purchase or delivery on the label of each product. Use the open products and then the oldest products first.
- Do not store flammable material with pesticides.
The above tips were compiled from Iowa State University's publication Store Pesticides Safely  (PDF), Cornell University's Shelf Life of Pesticides , and The Ohio State University's Pesticide User's Guide .