Editor’s Note: This article was reprinted with permission from Techletter, a biweekly training letter for professional pest control technicians from Pinto & Associates.
Granular pesticide formulations are dry products similar to dust formulations except that granules are larger and heavier and can’t be applied with a duster. A fine granular pesticide pours like sugar or salt. The active insecticide is coated onto or absorbed into carrier particles made from an absorptive material such as clay, pieces of corn cobs or walnut shells. The amount of active ingredient in granular pesticides is relatively low, ranging from 1 to 15 percent by weight. The symbol “G” is often used on the pesticide label to denote a granular formulation.
In the structural pest control industry, granules are used mostly around building foundations to prevent outside insects such as crickets, cockroaches, ants and millipedes from moving indoors. They also can be broadcast on lawns to control fire ants, mole crickets, larval fleas, ticks and other pests. Some granular baits are also labeled for indoor use, with special restrictions on use in food areas. Some granules are applied to soil but act as systemics, meaning they are taken up by a plant into its leaves to kill pests feeding on the plant. Granular pesticides are sometimes applied to bodies of water to kill larval mosquitoes and other aquatic pests.
Granular pesticides are applied outdoors with a rotary or drop spreader, or by hand. Some granular products are designed so that they can be shaken out of the package without requiring any special application equipment. Granules can also be placed inside bait stations. Once applied, granular pesticides release the active ingredient slowly; some must be watered-in after (or before) application to activate the insecticidal action. However, granular baits for cockroaches, crickets, ants and snails must remain dry.
Why Granules Are A Good Choice:
- when you need to kill ground-dwelling pests around an exterior foundation
- when controlling flies around Dumpsters and other garbage areas, if so labeled
- when you want a ready-to-use product; no mixing needed
- when you want a lower drift hazard than with dusts and sprays
- when you want lower hazard for the applicator because of reduced drift
- when you want to avoid concerns associated with solvents
- when you want a product that performs well on both porous and non-porous surfaces
- when you need to treat soil around heavy foliage; granules will drop to the ground below
- when a light rain is expected; you can skip the watering-in step on some labels
- when you want to apply fertilizer at the same time; mixing the two saves effort
Why Granules Might Not Be The Best Choice:
- when you are not adept at calibrating application equipment
- when treating plant foliage for pests since granules do not stick to the leaves
- when time is a factor; granules may require additional post-application steps of watering or raking into soil
- when cost is a factor; granules can be more expensive than other formulations
- when treating a property with outside pets; choose a smaller granule that doesn’t look like dry pet food and keep pets out of the area until the granules are watered-in and the area has dried
- when you are treating a newly seeded area or bare ground where birds are feeding and might pick up the granules
- when the indoor application site is a porous surface, some granules can leave a temporary stain if they get wet
- when you are applying granular bait outside and heavy rain is expected
- when there are serious drought conditions; the active ingredient may not be released in sufficient quantities to control the pest
- when you must apply close to the edge of a body of water
The amount of active ingredient in granular pesticides is fairly low, lower than an emulsifiable concentrate but usually higher than a dust. Because of the absence of pesticide drift, granular pesticides are relatively safe for the applicator. Wear gloves and long sleeves and avoid contact with your skin.
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