Mites is our focus in this week’s How to Grow Pot series where Mel Thomas, the author of Cannabis Cultivation: A Complete Grower’s Guide, answers your questions. Mel’s a world-renowned cannabis cultivator, and at one time was the largest producer of marijuana in the UK. Have a question for him? Then email us at stuffstonerslike[at]yahoo.com.
QUESTION: Looks like I have bugs. There’s discoloration that doesn’t wipe off the leaves. My grow is on day 51. Any advice?
MEL THOMAS: It’s spider mites from what I can see from the pics, bad infestation, bro. This will kill them in one hit, I don’t like using it close to harvest but if you don’t zap them you will have an infestation that will explode. Not sure about US availability, however. (1 oz. on ebay)
You’re very close to harvest and it may be better to pick out the infested leaves and keep the problem contained using neem oil or a similar organic treatment, the main concern is killing the mites so they don’t infect the next crop and the treatment I recommended is the most effective but its not organic and is better used during vegging. If you have a rotation setup going you will have to use the chemical treatment
Pick up a neem oil concentrate and dilute it per instructions, usually 3 capfuls to a gallon of water. Use a pump sprayer and spray the leaves, starting with the undersides, neem oil is safe to handle and non-toxic. It will control the problem but won’t zap all the eggs. Not really a problem as you are so close to harvest. Try and avoid spraying the buds unless they appear infected as well, it can encourage bud rot. Bag all the infected leaves carefully and dispose of them. You can pick up ready mixed sprays but it works out cheaper just getting the concentrate. Once you’ve harvested give the grow area a good clean and spray the area with neem. If your next crop shows symptoms opt for the chemical treatment during veg, i don’t much like using the chemical treatments but it is effective, one treatment during early veg will nuke them and save you a lot of problems later on.
A single dose of Floramite will last on the plant for 28 days ensuring all stages of mites from egg to larvae to adult will be eradicated. Spray Floramite at the first sign of a mite infestation and help control the situation before it spreads to other plants.
Usage Instructions: Wear breathable mask and protective clothing while treating crops. Mix 1 litre of water to every 1ml of Floramite. Shake well before use. Spray evenly to wet the leaves. Spray upper and lower surfaces of the leaves covering the entire plant. If the plants are soil grown spray soil surface as well. For maximum effectiveness this product requires thorough coverage of upper and lower leaf surfaces.