My outdoor marijuana plants are about a week away from harvest, but I’ve just noticed that a few of the top flowers are dying. They are dry and discolored. After investigating further, I noticed a larva chomping away. It looked almost indistinguishable from the leaf itself. What can I do to save my remaining flowers?
I’ve got a caterpillar that’s started eating away at my female marijuana plants. It’s about 1 to 2 mm in length with an off-white color. It spends most of its time crawling on the top side of the leaves, sucking them dry gradually and turning the affected areas brown. There are also a few tiny black specks and some honeydew contaminating the leaves. When my air-cooling system stopped working and the temperature increased from 70 to 78F to 80 to 92F, these pests increased. The humidity also rose another 20% because of the heat. Is there anything I can do?
Get rid of any caterpillars you come across, and check for more that you can just handpick. Once you’ve exhausted that avenue, try chemical or biological extermination agents.
Pyrethrum is an all-natural plant pesticide that comes from the concentrated secretions of a plant in the chrysanthemum family. Caterpillars and grubs are effectively killed by this pesticide. Just spray it onto the marijuana plant and watch as any remaining caterpillars stop eating and die. The pesticide won’t harm warm-blooded animals but it can be detrimental to cold-blooded animals like fish or reptiles. Thus, you shouldn’t use it around any cold-blooded pets or near any lakes or streams. Pyrethrum is useful for a limited time and comes in organic concoctions. Many marijuana growers use it for quick knockdowns. Read any instructions on a particular brand because some solutions are different than others. You can generally use most brands up until harvest time.
Another way to rid yourself of caterpillars is with bacillus thuringiensis (BT). It acts as an insect-specific plague that won’t harm anything but your grubs and caterpillars. In comes in many different brand names like Dipel. When sprayed on the plants, insects ingest it, get sick, stop eating, and die relatively quickly. When the insect dies, it releases more bacilli so that the infection is recurrent.
Botanigard is a fungus-based insecticide that is highly effective, but takes a couple days to really work its magic. You can use BT and Botanigard in conjunction with pyrethrum to cover all your bases.
I need to kill caterpillers ASAP…IT IS ALMOST HARVEST…BUDS ARE TRYIN TO GET HUGE…I have to almost destroy all my buds to find and remove them…how do i apply Pyrethrum, can you taste it when smoking… will it get to the deeply embedded caterpillers? how can i prevent them next year?
Be concerned about fungus. Bud rot from grey mold may start with caterpillar poop. Spray with diluted 3% hydrogen peroxide, maybe 50/50. Consider spraying with Seranade bacillus for mold, but on separate days as the peroxide can kill off the bacillus. Captain Jack’s or Spinosad has a bacillus that kills the caterpillars.
Is there any harm to ingest Spinosad if sprayed close to harvest? I’ve got these little bastards…just popped out this week. I found a few on leaves, but I assume these are the same kind that burrow into bud and cause rot.
Thanks!
Ok, going at this pest issue from a few different directions. They have had ZERO pest issues until now, of course. Outdoors. No cover. Just Mother Nature.
Should I do my pest management in the following order?
Hydrogen Peroxide H2O spray
Safer BT Cat Killer 11 (is there a difference BT-K between this and the Safer BT-K talked about? or one in the same?)
Spinosad (Like Capt Jacks) I use this on my chickens and coops actually to control mites.
Keep in mind that the hydrogen peroxide that we all use kills (sterilizes) microbes, such as BT and other helpful bacillus. Recommend waiting a day after peroxide before spraying bacillus products.
Spinosad is broken down rapidly by sunlight. In the presence of sunlight, half-lives on leaves are 2 to 16 days and less than one day in water. When applied to leaves, some spinosad can be absorbed. However, it does not readily spread from leaves to the rest of the plant. In the absence of sunlight, spinosad breaks down very slowly in water. Half-lives of more than 30 days to 259 days have been reported. However, it binds rapidly to sediment. The halflife in sediment, where no oxygen is available, ranges from 161 to 250 days.
Spinosad also sticks to soil and has a very low potential to move through soil towards ground water. In field studies, no break down products of spinosad were found below a soil depth of two feet. In the top layers of soil, spinosad is rapidly broken down by microbes. Soil half-lives of 9 to 17 days have been reported. After it is applied, spinosad is not likely to become airborne.
Can spinosad affect birds, fish, or other wildlife?
Spinosad is practically non-toxic to moderately toxic to fish depending on the species. It is slightly to moderately toxic to aquatic invertebrates. However, spinosad is very highly toxic to eastern oysters. Spinosad is practically non-toxic to slightly toxic to birds, based on studies with bobwhite quail and mallard ducks. It is moderately toxic to earthworms. Spinosad is very highly toxic to bees. However, evidence suggests that spinosad has little or no effect on honey bees and other beneficial insects after sprays have dried.