Are Spider Mites More Dangerous Than Space Invaders From Mars?

That’s essentially the unapologetic Russian first strike doctrine: protect the Motherland at all costs and annihilate the enemy at the first sign of territorial encroachment. The Western democracies, on the other hand, coyly pledge not to be the first to introduce nukes in combat. Save for black helicopters hovering over your outdoor grow, there is no greater threat to your Cannabis harvest than an infestation of Spider Mites. (http://www.ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html)

If past USA administrations had been bio-savvy about the so-called “War on Drugs” they would have bred massive populations of Spider Mites in a secret location – like Area 51- and then used C-130’s or B-52’s to carpet bomb distribute the pests on Cannabis fields, rather than spewing persistent poisons and herbicidal defoliants. Or even funnier, what if Uncle Sam had grown a few hundred acres of Industrial Hemp, collected the pollen, and crop dusted feminine Cannabis from California to Mexico . . . buh-bye Sensimilla, eh ? But I digress.

Before their telltale silky webs envelope your precious buds spider mites can be hard to detect since they are so tiny; I urge you to carry and use an inexpensive but highly effective LED Illuminated 30X Jeweler’s Loupe or even a hand held mini-microscope on your daily inspections. Check the underside of any leaf which exhibits yellowish speckles or stippling which may be caused by Spider Mites wounding the plant in order to feed on the juices within. The warmer and drier the weather, the faster Spider Mites reproduce.

Dense infestation can quickly weaken, wither and ruin any host plant. Indoors, exclusion is the best preventative. Quarantine new plants, disinfect tools, use HEPA filters on incoming air ducting; generally respect the cleanliness and integrity of your grow space like a medical clean room. Consider soil-less, hydroponic grow methods to reduce the chance of introducing insect pests. Outdoors, occasional applications of Neem oil during the vegetative growth phase can help to keep things in check.

As with any pest, I prefer to work my way up the ladder of mechanical and organic responses to keep the cannabis clean, green and free of harmful residues come harvest time, but with Spider Mites you may have to escalate very fast. Prune away, quarantine and safely dispose of any early isolated infested material; don’t be shy about sacrificing a few leaves, Colas or even an entire plant for the sake of your remaining crop. Next up, consider introducing one or more of the many natural enemies of Spider Mites including Predatory Mites, Minute Pirate Bugs and Lacewing Larvae. Avoid nuking Spider Mites with broad spectrum insecticides because when any survivors bounce back, all their natural enemies will have been killed off and the Spider Mites will party like it’s 1999, game over.

Insecticidal soaps and herbal oils such as Sesame, Clove and Cinnamon work well to kill Spider Mites. Don’t be stingy, you’ll need to thoroughly spray drench the plants; get deep into the canopy and under the leaves, soak every nook and cranny.

Master Growers, experienced sealed room indoor horticulturists, sometimes deploy a Sulfur Burner during the vegetative growth phase so long as no oils such as Neem are used for a few weeks before and after the application. The fumes of burning Sulfur are very effective against many destructive pests, but they’re also quite hazardous to humans; do your homework before unleashing this ultimate doomsday weapon of pest control.

Disclaimer: Any advice and opinions offered about the cultivation of cannabis by Bruce N. Goren are his own and do not represent the University of California or the Master Gardener Program.