While safety, security and environmental impact are the major concerns when storing pesticides, maintaining the quality of pesticides is also important during winter storage.
Here are some tips for winter storage of pesticides:
- Plan pesticide purchases so that supplies are used by the end of the growing season.
- Keep pesticides at temperatures above freezing, under dry conditions and out of direct sunlight. UMass Extension greenhouse BMPs recommend that pesticide storage should be restricted to a first story room or area which has direct access to the outside (according to the Board of Fire Prevention). Pesticides should not be stored in basements or outdoors.
- Read the label. Special storage recommendations or restrictions will be printed on the label.
- Write the purchase or delivery date of the product on the label with waterproof ink. Products may lose their effectiveness over several years.
- Ventilation is important for storage of most pesticides.
- Store herbicides separately from other pesticides to avoid cross contamination.
Below is a list of pesticide formulations and their general sign of quality deterioration:
- Emulsifiable Concentrate (EC) – Evidence of separation of components such as sludge or sediment. Milky appearance does not occur when water is added.
- Oils – Milky appearance does not occur when water is added.
- Wettable powder (WP) and Soluble powder (SP) – Excessive lumping; powder does not suspend in water.
- Granular (G) – Excessive lumping or caking
If a pesticide freezes, place it in warm storage (50° to 80°F). Shake or roll container every few hours to mix product or eliminate layering. If layering persists or if all crystals do not completely dissolve, do not use product. If in doubt, call the manufacturer.
Adapted from: New England Vegetable Management Guide
Resources
UMass Extension Greenhouse BMPs, Pesticide Storage, Handling and Disposal by Natalia Clifton, UMass Extension Pesticide Program
Pesticide Storage by John Bartok Jr., Agricultural Engineer and Emeritus Extension Professor, University of Connecticut
Tina Smith, UMass Extension and Leanne Pundt, UConn Extension
