As winter tightens its grip, it is important to keep in mind how cold temperatures may affect a Pest Management Professional’s (PMP’s) treatment tools. Although winterizing equipment is often a priority, sometimes PMPs forget the importance of correctly storing their pest control products. If a PMP has access to heated chemical storage or doesn’t carry seasonal formulas during the winter, the effects of low temperatures on the products will be minimal. However, some products are kept on hand for use even during the coldest months. These products may encounter freezing temperatures as a result of being stored in unheated areas such as a chemical storage building or overnight in a service vehicle. When a pest control product is left to the elements, it is important to understand the impact of cold temperatures.
Temperatures below 32o F may alter a pest control product in several ways, including:
- Reduce product performance
- Permanent formulation damage
- Crystallization or coagulation of the active ingredient or one of the inert ingredients
- Leakage from a damaged container
- Temporary separation of the formulation components after thawing
- Water soluble packaging becoming brittle and with a risk of breaking when handled
Product Formulation and Freezing
It is important to understand that each product possesses specific formulation characteristics which influence that specific product’s performance after exposure to cold temperatures. Two key characteristics are the type of product (liquid, bait or granule) and the specific formulation, such as emulsifiable concentrates (EC) or suspension concentrates (SC) or micro-encapsulations (CS). For example, EC formulations have a relatively low freezing point because they contain a higher content of petroleum-based solvents and little if any water. SC formulations are more likely to freeze because they are generally water based.
Sprayable Liquids
Sprayable liquid formulations vary widely in the inert ingredients category, which largely governs a product’s freeze tolerance. Liquid formulations that have become frozen vary in their ability to remain functional after thawing. Some products may freeze and thaw without any effects on the performance or the structure of the formulation. In other formulations, the ingredients may separate after thawing and never go back to their original condition.
Wettable Powders
Solid, non-bait formulations such as wettable powders (WP), water-dispersible granules (WG or WDG) and granules are typically not impacted by cold temperatures. However, it is important for these products to remain dry because moisture can cause caking.
Micro-Encapsulated/Capsule Suspension
Micro-encapsulated products, also known as capsule suspension (CS) formulations, are usually unaffected by freezing and thawing. However, this largely depends on the manufacturing process and the specific formulation. Demand® CS and Demand EZ from Syngenta are two examples of high quality formulations that withstand the effects of freezing and thawing, as well as the challenge presented by high temperatures.
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Demand CS is formulated as a CS which contains 9.7% lambda cyhalothrin (the active ingredient), water and other inert ingredients, including ones that minimize the effects of freezing. The active ingredient is contained in tiny polymer microcapsules (about 12 micron average diameter) which protect it from harsh environmental conditions, including freezing.
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The Demand EZ formulation is similar but contains 2.4% lambda cyhalothrin (the active ingredient), water and inert ingredients.
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The difference in concentration lends a higher freezing point for Demand EZ, 23.7o F, compared with 21.9o F for Demand CS.
Bait
Bait formulations also vary in the degree to which they are affected by freezing. Since bait products require the pest to ingest the product to be effective, the primary concern with cold temperature exposure is whether the palatability remains intact. Although products vary, most solid baits are less affected by freezing than gel or liquid baits.
Steps for Handling Frozen Pest Control Products
- To prevent product leakage, place the container of frozen product inside a larger bucket.
- Inspect the container of product to determine if it is broken or cracked.
- Thaw at room temperature; do not heat.
- After thawing, carefully shake the container.
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If the product has the same appearance as before freezing, it is usually fine to use.
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If the formulation separates, does not reconstitute after shaking or becomes discolored, you should be suspect of the integrity of the product. Contact the product manufacturer for specific instructions.
Product Storage Recommendations
Always consult the product label for specific storage recommendations. For Syngenta products, the label recommendations are listed in the table below.
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