Pesticides formulations: Micro-encapsulated Pesticides
A pesticide formulation is a combination of active and inert ingredients that forms an end-use pesticide product. Pesticides are formulated to make them safer or easier to use. This is because many pesticide active ingredients, in “pure” (technical grade) form, are not suitable for application. In their concentrated form, some are extremely toxic, many do not mix well with water, some are unstable, and some are difficult (or unsafe) to handle, transport, or store. To address these problems, manufacturers add inert ingredients to end-use pesticide products. Inert ingredients have no pesticidal activity, and some simply serve as diluents or carriers.
Micro-encapsulated pesticides are dry particles or liquid droplets surrounded by a coating. Coatings may be plastic, starch, or some other material. Micro-encapsulated pesticides are mixed with water and applied as a spray. Once applied, the pesticide is released from the capsule. In some situations, the encapsulation process can provide “timed” slow release of the active ingredient. Depending on the physical properties of the coating, release of the pesticide active ingredient may be weather-dependent. If the release is slower than normal (for example, due to dry or cool weather), residues may remain on treated plants or surfaces longer than expected. As a result, some micro-encapsulated products have relatively long restricted-entry or preharvest intervals.
Some micro-encapsulated pesticide products contain highly toxic materials with a coating to increase handler safety. Others are micro-encapsulated for different reasons; for example, to reduce staining or odor or to protect the active ingredient from photo-degradation Highly toxic micro-encapsulated pesticides may be very hazardous to bees if the particles do not break down quickly and are the same size as pollen grains. For aging bees may collect them and carry them back to the hive. Later, when the coatings break down and release the pesticide, the colony may be poisoned. Some micro-encapsulated soil-applied products may be more prone to leaching.
- Coatings help protect the applicator.
- Easy to mix, handle, and apply.
- Timed release of active ingredient prolongs effectiveness (i.e., may result in fewer applications; application timing may be less critical).
- Reduced volatility.
- Reduced odor.
- Less likely to stain or otherwise damage treated surfaces.
- Reduced phytotoxicity.
- Constant agitation may be necessary in spray tank (depending on the properties of the coating).
- Risk of injuring or killing bees (if the micro-encapsulated product is toxic to them).
- Long restricted-entry or preharvest intervals for highly toxic products.