Casoron is the trade name for the chemical herbicide dichlorobenzonitrile, which is used for selective and total weed control. This herbicide forms a vapor obstruction in the soil's upper layer that is activated by contact with rainfall or irrigation water. The chemical causes weeds to die, and germinating seeds located in or below the barrier zone are destroyed when their new roots and shoots come in contact with the barrier.

Application of Casoron to Soil

Casoron or dichlorobenzonitrile must always be applied to soil even if it is to be applied as total weed control under trees, and it can be applied in the form of granules or distributed loosely as a wetting powder agent during ground or aerial application, according to Cornell University Cooperative Extension. Granules of the herbicide are used to destroy weeds in ponds and lakes.

Casoron/dichlorobenzonitrile evaporates very quickly from the soil if variables such as high temperature, wet soil and low relative air humidity exist; however, from dry soil, evaporation is subject to soil types and temperature influences. The chemical should be applied just before rainfall on dry soil to heighten its efficiency, and further enhancement is attainable by irrigation after the herbicide's dry soil application.

Expert Toxicity Insight

Tests on chronic toxicity of the herbicide, including liver function tests as well as an investigation into embryonic effects, revealed that the lowest nontoxic effect level was measured at 20 ppm on rats, and no significant local skin reactions were discernible on animals at any dose level of dichlorobenzonitrile.

No adverse effects on wildlife were evident during the product's herbicidal testing measures, and no toxicity levels were observed for mammals; nor is there acute toxicity to fish when the chemical is applied at herbicidal strength.

No Ecological Danger

Dichlorobenzonitrile's evaporation is guaranteed because of the high and volatile qualities of the chemical and its shared distillation properties with water; thus, the loss of the herbicide from soil surfaces is quite rapid and presents little ecological danger, according to Cornell University Cooperative Extension. Application of recommended herbicidal rates provides lasting coverage for a period of two to six months and, under favorable conditions, up to one year.

Chemical Exposure Warning

If you suspect poisoning by dichlorobenzonitrile has occurred, immediately contact a physician or get to the nearest hospital or poison control center. Be aware that this herbicide might produce moderate irritation to the respiratory tract and the skin, and you should wash contaminated skin with soap and water.

Compatibility and Storage Caution

Dichlorobenzonitrile when applied as a suspension in water does not deteriorate and is compatible with most wetting powder herbicides, and you should not mix this product with other water-soluble fertilizers or emulsified herbicides.

The shelf life of this product is at least two years when stored in a cool and dry area, and make sure to enclose dichlorobenzonitrile in tightly closed containers because of the product's volatility. In the event of an emergency, day or night, call the Chemtrec emergency line: 800-424-9300.