Pests and Predators

Marijuana Horticulture

by Jorge Cervantes

Once your plants are in the ground, well-fed, and watered, check them weekly for pest and fungal damage. Inspect the top and bottom of leaves for stippling (small pots) from mites or damage from chewing insects and slugs and snails. First identify the pest, and then determine a curse of action.

Properly grown outdoor cannabis has few problems with pests. Low tech, natural approaches to pest control work well. A few large pests like caterpillars and snails can be hand picked from the foliage. Caterpillar populations can be reduced at the source by installing bat houses.

Resident bats will eat moths and decrease the numbers of chewing caterpillars. Birds will eat caterpillars too, as well as aphids and other insects. Attract birds with suet, bird houses, baths, and feeders but cover tender seedlings and clones with wire or nylon mesh to protect them from birds too! Ladybugs and praying mantis are good options for insect control and can be purchased from nursery supply stores.

barns owls eat mice, gophers, and voles, but are hard to come by in the city. If you are lucky enough to have them nearby, take advantage of their ability to eat plant pests. On the other hand, some rodents, like moles and shrews, help your garden by dining n slugs, insects, and larvae.

Marigold cultivars of the Tagetes erecta and T. patula species, will repel nematodes, also known as eelworms, from the soil for two to three years if they are planted in an infested area and then tilled under. Just planting them in an area doesn’t accomplish anything. Numerous tests indicate that they do not have an effect on insects above the ground.

Frogs and Toads

Frogs and toads eat insects and slugs. The frogs will need a water source, while toads are more terrestrial. Large snakes in the garden will eat gophers, squirrels, and mice as well as the moles and shrews. Snakes can give you a good scare if you come across one unexpectedly! The snake will also want to eat your frog. Plan carefully before committing to any mini-predator solution to pest infestation.

Birds

Although most birds are welcome guests in most gardens, there are some that can make quick work of tender seedlings or new clones.

The most effective way to keep birds from freshly planted seed and transplants is to cover plants with plastic wire or plastic netting. When installing the netting, make sure it is securely fastened around the perimeter of plants so hungry birds do not get underneath.

Deer and Elk

Deer and elk love newly formed growth f cannabis pants. In addition, they may destroy crops by trampling them. Elk are somewhat of a problem, and deer are a problem!

A cage around pants is the best deterrent. But remember, the wire may be easy to spot if it is not discreet in color. Deer are repelled by the smell of blood and human hair. Pace handfuls of dried blood meal in cloth sacks and dip in water to activate the smell. Hang sacks from a tree to discourage dogs and other predators from eating them.

Handfuls of human hair can be placed in small cloth sacks and hung fro a fence or tree branch as a deterrent. Do not use your own hair; it could turn into evidence for police! Scented soaps have repelled deer from some gardens. But if deer are very hungry, the smell of blood meal, human hair, scented soap, or anything else will not deter them.

Always urinate in several locations around the perimeter of the garden so animals take your presence seriously. Some growers save urine all week and disperse it at regular visits to their patch.

Deer easily bound over eight foot fences. A good deer fence is eight feet tall with the top foot sloping outward, away from the garden at a 45 degree angle. Electric fences and large dogs are also excellent deterrents.

Gophers

Pocket gophers are small burrowing rodents that eat plant roots and foliage. These herbivores find fleshy roots a real treat and occasionally attack cannabis. Should a family of gophers move int your area, get rid of them as son as possible. Females can bear up to five litters of four to eight offspring a year. A family of gophers can clean out a large garden in a matter of weeks.

The only sure way to get rid of gophers is by trapping. There are several gopher traps available, including ones that capture them alive. It will take some skill before you are regularly able to catch gophers with traps. You must avoid getting human scent on any part of the traps. if gophers sense the human odor, they will simply push soil over the trap to spring it or render it otherwise ineffective. Traps are put in gopher runways and so don’t need to be baited.

A fence f poultry wire f 0.5 inch hardware cloth buried one foot deep and standing 3 feet above ground will exclude gophers. Line panting holes with chicken wire before filing with soil. Driving metal sheets around the perimeter f planting holes will also prevent gopher damage.

Mice and Voles

Mice and voles can chew back from around the base of cannabis plants. If this is a problem, keep mulch a foot away from plants, and install a wire mesh around the trunks. Mice and voles make nests in large piles of mulch, and they are attracted to stored water. Cover all water sources to exclude them, but keep in mind that they might chew through the container if water is super scarce.

The best mouse deterrent is a cat that is serious about hunting. Mousetraps also work well on smaller populations. Removing a large number of mice with traps can be tedious and unpleasant.

Do not use poison! Scavenger animals will eat the dead rodents and may become poisoned themselves.

Moles

Moles are minor pests. They are primarily insectivores that eat cutworms and other soil grubs, but their tunnels may dislodge cannabis roots.

Repel moles with castor plants or gopher plants Euphorbia lathyris. Castor bean eaves and cantor oil, as well repel moles if put into their main runs.

Blend two tablespoons of castor oil with three tablespoons of dish soap concentrate and ten tablespoons of water. Mix in a blender. use this as a concentrate at the rate of two tablespoons per gallon of water. Apply as a soil drench directly over mole holes.

Barrel traps, scissor traps, and guillotine traps are effective and kill moles instantly.

Rabbits

Rabbits eat almost anything green, and they multiply like rabbits! Repel rabbits with a light dusting of rock phosphate on young leaves of dried blood sprinkled around the base f plants. Manure tea sprayed on leaves and soil may keep them from dining on your plants. Rabbits find plants dusted with hot pepper or a spray of dilute fish emulsion and bone meal repulsive. There also are a number of commercial rabbit repellents, but be wary of using these on consumables!

A dog will keep rabbits in check, but the only surefire way to keep rabbits out of the garden is to fence them out with one inch poultry wire. The poultry wire should be buried at least six inches in the ground to prevent burrowing and rise two to three feet above ground. Wrap trunks with a wire mesh to keep rabbits from chewing bark in winter and early spring.