Cannabis Pesticide Management
Cannabis Pesticide Management – Cannabis pests vary according to cultivar (variety), whether the plants are grown indoors or outdoors, and where the plants are grown geographically. The pests included in this review are preliminary and based on the following sources: a presentation given in 2013 by Whitney Cranshaw, an extension entomologist at Colorado State University, and a review article by John M McPartland, a professor of family medicine at the University of Vermont.
We also received input from Kevin Hoffman, former Primary State Entomologist, California Department of Food & Agriculture (CDFA).
PRODUCTS THAT CAN BE LEGALLY APPLIED TO CANNABIS PRODUCTS IN CALIFORNIA
A pesticide product can legally be applied to cannabis under state law if the active ingredients found in the product are exempt from residue tolerance requirements1 and the product is either exempt from registration requirements2 or registered for a use that’s broad enough to include use on cannabis. Residue tolerance requirements are set by U.S. EPA for each pesticide on each food crop and are the amount of pesticide residue allowed to remain in or on each treated crop with “reasonable certainty of no harm.” Some pesticides are exempted from the tolerance requirement when they’re found to be minimal risk. Active ingredients exempt from registration requirements are mostly food-grade essential oils such as peppermint oil or rosemary oil.
For damage caused by greenhouse pests, we used information from Cranshaw’s presentation; for that of outdoor pests when there wasn’t any overlap, we used McPartland’s list and information from UC IPM for various crops. Accounts of damage by rodents are anecdotal
PESTS NOT OFFICIALLY IDENTIFIED IN CALIFORNIA
Several cannabis pests in other states are not yet known in California. These pests would add to the russet mites, aphids, cutworms, budworms, borers, and flea beetles already in California. As more and more cannabis is planted throughout the state, collecting potential pests will enable entomologists to identify new species.
THE IMPORTANCE OF CORRECT IDENTIFICATION.
It’s essential to identify the potential pest or you may launch a futile program for a mite or insect that isn’t a pest. And likewise, you need to know the correct species or you may use the wrong management strategy. For accurate identification, bring specimens to an entomologist.
HOW TO PRESERVE SPECIMENS FOR IDENTIFICATION.
If the insect specimen is hard-bodied (e.g., a beetle or moth), carefully place it in a small pill vial and cushion with crumpled tissue paper. If your specimen isn’t yet dead, put it in a jar and place in a freezer overnight. Do not wrap specimens in tissue and seal them in plastic bags or you’ll end up with smashed bug parts. Place soft-bodied specimens (e.g., mites, leafhoppers, aphids, caterpillars) in a jar filled with rubbing alcohol. Include written information such as where on the plant you found the specimen, the general location of the plant, and date captured. Note original color and texture, since these will change once you immerse the specimen in alcohol. Also helpful are photographs of the specimen in its original habitat.