Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, May 27, 1993 TAG: 9305260129
SECTION: CURRENT PAGE: NRV6 EDITION: NEW RIVER VALLEY
SOURCE: Joe Hunnings
DATELINE: LENGTH: Medium
Gardeners and farmers are encouraged to implement alternative controls wherever possible.
However, when chemical controls are necessary, the user should be very knowledgeable about their proper application.
To apply pesticides correctly, you must know about formulations.
The formulation describes the physical state of a pesticide. A chemical may be available in variety of formulations.
Pesticides rarely are applied full strength.
The chemical in the pesticide formulation that actually kills the pests is called the active ingredient. The added chemicals, those that make the product easy and safe to formulate or apply, are called inert ingredients.
The following common pesticide formulations are divided into two groups - formulations that require mixing, and formulations that are ready to use when they are purchased:
Formulations requiring mixing
\ 1. Emulsifiable concentrates (EC or E): The active ingredient is mixed with an oil base (often listed as petroleum derivatives), forming an emulsion that is diluted with water for application.
Because they're easy to mix and use, ECs are common in the home-garden trade. They can cause minor surface bronzing of light-colored fruit.
These pesticides should be protected from freezing temperatures that can break down the emulsifier.
\ 2. Flowables (F or L): A flowable, or liquid, can be mixed with water to form a suspension in a spray tank.
\ 3. Wettable powders (WP or W): Wettable powder formulations are made by combining the active ingredient with a fine powder. They look like dusts, but they are made to mix with water.
These formulations need continuous agitation to maintain a suspension that makes them difficult for home gardeners to use.
When mixing a WP, first mix the measured quantity with a small amount of water, forming a slurry. (A paper cup with a popsicle stick makes a good disposable mixing container.)
Then, add the slurry and the additional water to the spray tank.
Shake the spray tank frequently to maintain the suspension.
\ 4. Soluble powders (SP): A soluble powder formulation is made from an active ingredient in powder form that dissolves in water.
Ready-to-use formulations
1. Solutions (S): These formulations are pre-mixed, ready to use. They are often found in household pest products.
\ 2. Aerosols (A): These are very low-concentrate solutions, usually applied as a fine spray or mist.
They are generally sold in aerosol cans and are a very expensive pesticide source.
\ 3. Dusts (D): Dust formulations are made by adding the active ingredients to a fine inert powder or talc.
They are generally used dry.
\ 4. Granules (G): Granular formulations are made by adding the active ingredient to coarse particles (granules) of inert material like fired clay particles.
\ 5. Baits (B): A bait formulation is made by adding the active ingredient to an edible or attractive substance.
Baits are often used to control slugs, snails, or small ground insects and rodents.
Gardeners often confuse sprays and dusts. Dusts are a type of formulation, but sprays are one means to apply several different formulations such as wettable powders or emulsifiable concentrates mixed with water.
If you would like to know more about safe and proper pesticide usage, ask for a copy of the 1993 Pest Management Guide.
This guide provides the latest recommendations for controlling diseases, insects and weeds.
It's available through your local Virginia Cooperative Extension Service office.
by CNB