Neem Oil

Marijuana Horticulture

by Jorge Cervantes

Ingredients – Purified extract from neem seeds. Buy only cold-pressed oil that is stronger and contains all the natural ingredients. Do not use heat processed neem oil. Cold pressed oil also contains azadirachtin, the active ingredient in neem. Brand names include Neemguard, Triact, and Einstein Oil.

Controls – Effective against spider mites, fungus gnats, and aphids. It is also a fungistat against powdery mildew and rust.

Caution – Neem oil is very effective against spider mites.

Mixing – Mix just before using in water with a pH below 7 and use a spreader-sticker. Agitate constantly while using to keep emulsified. Throw out excess.

Application – Spray on foliage, especially under leaves, where mites live. Apply every few days so hatching larvae will eat it immediately. Spray heavily so mites have little choice but to eat it. Avoid spraying the last few days before harvest. Some growers report a foul taste when applied just before harvest.

Persistence – Contact neem stays on foliage for up to a month or until it is washed off. Stays in plant system up to a month when absorbed via rots.

Forms – Emulsifiable concentrate.

Toxicity – Toxicity to beneficial insects has been reported. Not toxic to humans.

Safety – Irritates eyes, wear a mask and gloves.