Thursday, 6 January 2011

Insects and Other Pests

Outdoors, where it functions as part of an ecological system, marijuana is less susceptible to insect attacks than it is indoors. In an outdoor environment, insects are subject to the vagaries of the weather, food supply, and predators. And marijuana grows so fast that insects usually do little damage. Plants, plant eaters, and predators usually maintain an equilibrium which minimises damage. But this balance is disturbed by tilling and gardening, and may take a while to re-establish itself.

The soil surrounding your plants may be teeming with insects, and it would be unnatural not to see some on your plants. Most insects do not eat marijuana. The few that do are the food which helps to keep a small population of their predators alive. Insects in the garden need to be controlled only when there is a real threat of damage.

Marijuana is most vulnerable in its early stages. After the plant increases production of the cannabinoids and resins at the eighth or ninth week, most insects are repelled. When the plants are small, an occasional munch affects a relatively larger part of the plant. That same bite affects a relatively smaller part when the plant is larger.

The insects that infect marijuana indoors - aphids, mealy bugs, mites, and whiteflies - do best in humid conditions with constantly warm temperatures. Outdoors they rarely inflict much damage on marijuana. The pests that are most likely to damage marijuana are leafhoppers, treehoppers, cucumber beetles, thrips, flea beetles, several kinds of caterpillars, snails, and slugs. The younger the plants are, the more susceptible they are to attack. Your prime goal is to protect the plants during the first two vulnerable months. You need to keep the pest population low, so that the damage is relatively light. The pests don't have to be eliminated, only kept under control.

There are many ways to keep pests from damaging your crops. These fall into one or more of several categories: biological control; capture traps and barriers; home remedies; and chemical insecticides.

Biological Control
The theory behind biological controls is that methods for control of pests can be found within nature. These methods are safer to humans and less damaging to the environment than commercial insecticides. Gardeners have many forms of biological control at their disposal, including companion planting, use of predators, and sprays made from plant extracts or ground-up insects.

Companion Planting
Some plants, including marijuana in its later stages, produce resins or essences which repel or kill plant pests. Some of them are general repellents that affect a broad range of plant pests; others affect specific species. Generally, the heavily scented plants, such as spices, mints, and other herbs, are most likely to have these qualities.

Some of the more familiar plants used to protect gardens are the Alliums, or onion family, with garlic, chives, green onions, and other oniony-type plants as members. This group repels a broad range of plant pests such as aphids, spider mites, flea beetles, potato bugs, bean beetles, and many other insects, as well as rabbits and some deer. They are easily planted around the garden or between the marijuana plants. Just plant onion bulbs or the cloves from a garlic bulb so that the top of the bulb is about one inch deep. One garlic bulb yields quite a few cloves; so a large garden requires only a few bulbs.

Geraniums are reputed to repel leafhoppers and many kinds of beetles. These plants prefer a dry soil, thrive in full light, and usually grow two feet tall. Geraniums should be interspersed with the marijuana, or potted geraniums can be set out if problems develop. Tansy (Tanaetum vulgare) is a tall, fragrant, woody perennial which grows five feet tall. It protects against cut-worms, beetles, cucumber beetles, and other eaters and borers.

Mints repel many insects and are sometimes used as mouse repellents. They are especially useful for the control of the flea beetle. They thrive in semi-shaded areas with rich soil.

Marigolds can be planted to eliminate nematodes. They are fast-growing annual plants which flower profusely. They come in many varieties, ranging in height from six to 30 inches. They grow in a wide range of soils and do best in the sun. The scented varieties - usually nonhybrids - offer the most protection.

All companion plants must be planted close to the plants to be protected, since their repellent qualities spread only a short distance beyond their circumference. They are effective when they are planted before the damage is apparent, and offer long-tern protection. They are used when a pest is expected. For instance, growers in the San Francisco Bay Area expect rose leafhoppers to attack their plants. Since geraniums grow in the area as perennial plants, some growers plant them permanently in the garden. As the geraniums develop into small bushes, the hoppers leave, never to return.

Many of the insects in your garden are called beneficials, because they perform a useful service in the garden. Some of them eat decaying matter; others help in the pollination process; and some pry on insects which damage crops. Almost everyone is familiar with the ladybug, which eats aphids and insect eggs and has a voracious appetite. They are available commercially by the pint. The praying mantis eats slow-moving insects. When it first hatches, it starts out on aphids and mites. But as it grows larger, it eats bigger insects and worms. Mantis-egg cases are foam-like, straw-coloured masses which contain 100 to 300 eggs. These cases are sold commercially but can also be found in the late fall in bushy areas. Another insect which is sold commercially as a plant protector is the green or brown lacewing. It has golden eyes, looks fragile, and flies erratically. But in their larval state, lacewings eat thrips, mites, caterpillar eggs, scale, leafhopper nymphs, aphids, and mealybugs. The trichogamma wasp is an egg parasite which lays its eggs in the eggs of over 200 species of insects, including many moths and butterflies which hatch into worm pests. Cryptolaemus is used to destroy mealybugs. Adults are released when mealybugs appear in the spring. They seek out the mealybug colonies and lay their eggs. When the eggs hatch the larvae wander around the infested area and eat the young mealybugs.

The use of commercially bred or gathered predators is most feasible in large gardens or fields. The insects may not have much effect on small gardens, since they wander off to find food and may never return. Try to buy from manufacturers who intentionally do not feed their product before shipping. Hungry predators are more likely to stay and eat the pests.

Insects are just one groups of predators. Birds such as purple martins, robins, blue jays, chickadees, and even starlings and English sparrows eat large quantities of insects and other small pests. They can be attracted to the garden by placing a feeder, bird houses, and water in the area. When plants get larger, some gardeners let chickens, ducks, or geese run through the garden. In a short time, they pick it clean of pests and weeds. Reptiles and amphibians, including frogs, toads, snakes, lizards, and turtles, all eat garden pests and should be encouraged to make a home in the garden.

Homemade Repellents and Insecticides
Another way to control garden pests is to make sprays from plants which repel insects by using a juicer or blender or by baking a tea. Ingredients can be found in most kitchens. Chile pepper, garlic, coffee, horseradish, radish, geranium, and tobacco are the usual mainstays of herbal sprays, although most strong-smelling herbs and spices have some repellent qualities. Many gardeners experiment to see what works in their garden. For instance, if an insect which bother marijuana stays clear of a nearby weed, a tea or blended spray made form that plant may control the pest. But try it on only one plant (or part of a plant) first, because the spray may also be harmful to the marijuana.

Garlic is probably the most popular ingredient for general-purpose sprays made from kitchen ingredients. A typical formula is to soak three ounces of chopped or minced garlic in a covered container of mineral oil for a day. Then, slowly add a pint of lukewarm water in which a quarter ounce of real soap (Ivory will do) has been dissolved. Stir and let stand several hours, than strain. Use as a concentrate, adding between 20 to 100 parts water to one part concentrate.

Other recipes call for boiling the garlic or for grinding or juicing it. Some brewers add other spices to the basic formula. One recipe calls for one clove garlic, three cayenne peppers, one onion, a quarts ounce of soap, and sufficient water to blend. Let it sit for three or four days before using, and use one part concentrate to 20 parts water. Homemade tobacco teas are sometimes used as insect sprays. Use one cigarette in a quart of water. Let it brew 24 hours before using.

Snails and slugs are attracted by yeast solutions, which are easily prepared from cooking yeast, sugar, and water. This is also why gardeners have success trapping these leaf munchers in bowls of stale beer. Place deep-sided containers at the soil level. The pests slide in and drown.

Gardeners should not overlook handpicking as a viable method of pest control. The foot or a quick thumb and forefinger can eliminate large numbers of pests and can keep a small garden pest-free. Collect the bugs and drop them in a tin can with some alcohol to kill them. Early morning is the best time to collect pests, since they are slower-moving until the sun warms them.

Snails, slugs, earwigs, and some other insects gather in cool, moist areas during the heat of the day. By providing just such a space in a garden, many of these pests can be located and destroyed. Place pieces of cardboard or boards around the garden; look under them each day.

Home Remedies
Gardeners and farmers have discovered and invented ingenious ways to control insects without harming the environment. Some of the more popular ones are listed here, but there are many more, each suited to a particular situation.

Soap and water is an effective control measure for mealybugs, mites, leafhoppers (nymph stage), leaf miners, and aphids. Simply wash the plants thoroughly with a solution of two tablespoons of soap dissolved in a gallon of water. Rinse the soap off thoroughly. (Some growers feel that the addition of kerosene or alcohol makes the solution more effective, but these can harm the plants and dissolve THC.) This treatment does not eliminate all of the pests, and may need to be repeated weekly, but it does keep them under control.

Sprays are sometimes made from healthy insects, which are caught, ground up, and then sprayed back onto the plants. When the pests come in contact with the spray, they become infected with the pathogen and get sick. This method is very effective, and is considered safe, but it is not easy to capture sick insects. A variation in this technique was described in the October 1976 Organic Gardening and Farming Magazine, in which a spray was made from healthy insects. In a followup article in the May 1977 issue, the authors theorised that any population of insects contains pathogens. If enough insects are collected, some of them are sure to be sick, and they contain enough germs to spread the disease. To make an insect spray, capture about a hundred pests. (Make sure not to include any beneficial insects or the spray may also work against them.) Using a blender, mix them with a cup of spring water, strain, and dilute with enough water to spray your garden.

Whenever making or storing sprays, use a glass container. Metal or plastic ones may react with the chemicals that the liquids contain.

Another home remedy for the control of mites and aphids is a mixture consisting of a half cup of milk in four cups of wheat flour, added to five gallons of water. When it is sprayed on the undersides of the leaves, it suffocates the insects and then flakes off as it dries.

Some growers use mulches to control insects. Cedar chips repel beetles, moths, mites, and mealybugs. Aluminium foil is used for aphid and thrip control on small plants; the reflected light disorients them and they do not land on the plants. A sprinkling of cream of tartar eliminates ants, and boric acid kills roaches. Sulfur powders, available at nurseries, are used to control mites and fungus infections.

Organic Insecticides
Pyrethrum, rotenone, and ryania are effective insecticides which come as powders (dusts) or sprays. They are concentrated form of naturally occurring plant substances, and are considered harmless to warm-blooded animals when used as directed.

Ryania, which is found in the roots of a tropical shrub, is most effective against chewing insects, worms, and larvae, which it incapacitates, rather than kills.

Rotenone is a general-purpose insecticide with little residual effect; that is, it breaks down soon after application, and is therefore one of the safest insecticides. Two or three dustings during the seedling stages afford protection against most insects and bugs.

Pyrethrum is one of the most powerful natural insecticides, and is effective against a wide range of pests. It is also relatively nontoxic to bees and ladybugs. Pyrethrums are found in the pyrethrum plant as well as in chrysanthemums. They are non-persistent, and in small doses may make the insects sick without killing them. These insecticides are available at many nurseries and may provide the surest, easiest form of protection against serious insect attack.

Barriers and Traps
In gardens and small farms, insects and other pests are sometimes controlled by the use of traps and barriers that prevent them from reaching the marijuana. When the plant are young, they can be protected from cutworms, caterpillars, snails, and slugs by a collar that is buried an inch into the ground and is six inches high. Some growers face it with aluminium foil, which many insects seem to dislike. One ingenious grower painted collars with molasses to capture the crawlers. She also caught a significant number of leafhoppers. Commercial stickums such as Tanglefoot can also be used to trap insects.

Snails, slugs, and some crawling insects are repelled by a border perimeter of lime, potash (wood ash), sulfur, sharp sand, or cinders. Place a thin layer, six inches wide, around the perimeter of the garden, or around each plant. Flea beetles and some other flying insects are repelled by wood ashes dusted on the leaves. The powders are water-soluble; so they should be replaced after a heavy rain. Crawling pests sometimes have a hard time reaching plants grown in containers or raised beds.

Flying insects, such as leaf and treehoppers, can be prevented from getting to plants by barriers made from cheesecloth. Other growers place cardboard sticky with glue between plants, and then shake the plants. The cardboard catches a good proportion of them. One innovative grower in Palo Alto, California, placed a furniture crate, with the top cut off and with Tanglefoot spread on the inside, around each of his six plants. He said that by shaking the plants, he eliminated leafhoppers in four days.

Chemical Insecticides
Insecticides were developed as an easy way to control pests. They have an immediate dramatic effect, but the long-range damage that they do to the entire ecological system is sometimes overlooked. The chlorinated hydrocarbons, such as DDT, DDC, Aldrin, Kelthane, and Dieldrin, were the most dangerous commercial insecticides. They affect warm-blooded animals and are no longer available. (In no case should any of these by used.)

Diazinon, Sevin, and Malathion are three insecticides which are often soil in nurseries to protect vegetable crops. They are considered safe for warm-blooded animals and have a limited residual effect, since they break down in a few days. But these insecticides are not too selective and may kill beneficials as well as pests. Sevin is the most toxic and kills the widest range of insects, including bees.

These chemicals come as sprays, powders, and baits, formulated for specific pests. They should be used only when an intolerable situation has developed. Plants should be harvested only after the required safety period has passed since application. This period is from two to 35 days, and is specifically listed on all insecticides that can be safely used. Insecticides should be used and handled carefully, following instructions, wearing protective clothing, with no children or pets around. It is advisable to use a mask when applying dusts and to work upwind.

Common Pests
Cucumber Beetles:

Cucumber beetles are about a quarter-inch long and look a lot like ladybugs. There are several species of cucumber beetles. The striped beetle is found east of the Rocky Mountains. It is yellow, has two or three black stripes running down its back, and has a black head. The spotted cucumber beetle has a yellow-green back with 11 or 12 black spots and a black head. There are related species, such as the banded cucumber beetle, throughout the United States. The larvae of all varieties are white, turning brownish at the ends, slender, about one-third inch long.

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Cucumber beetles do the most damage in the early spring, when the adults come out of hibernation and begin to eat the new growth and leaves. These leaf-eating adults damage young marijuana, especially when there is a scarcity of other food. They also transmit bacterial diseases and viruses to the plants. Within a few weeks after they come out of hibernation, they lay their eggs at the base of plant roots. The larvae of the striped cucumber beetle feed only on melon- and cucumber-type plant roots. The spotted-beetle larvae are fond of corn, and are known as the "Southern cornroot worm" in some places.

The best way to prevent cucumber-beetle attacks is to keep the areas that you plant isolated from corn and melon plantings. Heavy mulching or tilling destroys the pests when they are hibernating. Late plantings minimise damage inflicted by cucumber beetles.

Cucumber beetles can be controlled by use of Rotenone or Malathion. Dust several times during seedling growth. These beetles are also prey to many insects, including the common garden soldier beetle, predator flies, wasps, and nematodes. Hand picking is also an effective control for cucumber beetles.

Thrips are slender, yellow or brownish, winged insects about 1/25 inch long. They have fragile wings which keep them aloft while they are blown by the wind. Thrips have a cone-shaped mouthpart, which they use to cut stems in order to suck plant juices. The larvae look like adults, but are smaller and wingless. Most thrips feed on a range of plants, especially onion and other bulbs, and marijuana is at most a marginal part of their diet. A well-cultivated marijuana plant can outgrow and damage that thrips are likely to inflict.

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Thrips hibernate in plant debris during the winter and begin sucking in early spring. They lay eggs during warm weather, and can produce a new generation every two weeks. Since thrips eat a varied diet, keeping the garden area clear of weeds is an effective control. Thrips can also be controlled by turning debris under, so that their nesting sites are destroyed.

Thrips can be controlled by use of tobacco sprays. Rotenone, or Malathion. Aluminium-foil mulches are effective thrip repellents. The light reflected from the foil confuses their sense of direction.

Flea Beetles
There are many species of flea beetles. The adults range in size between one-twentieth and one-fifth of an inch, and are usually black or metallic green or blue. They are called flea beetles because they use their enlarged hind legs to jump like fleas when disturbed. Many flea beetles are host-specific, and probably only a few species munch on marijuana.

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Flea beetles hibernate in plant debris. By ploughing the debris under, their hibernation places are eliminated, and there should be few pests the following spring. Flea beetles are repelled by a mixture of equal parts of wood ashes and limestone sprinkled on foliage every few days. Containers of the mixture may also by placed around the plants. Garlic sprays also repel flea beetles. The chemical poisons used specifically for flea beetles are stomach poisons, which break down slowly and may not be safe to inhale. Home remedies are best for flea beetles.

Vertebrate Pests

Until it develops a hard fibrous main stem, usually at about two months, the young marijuana plant attracts rodents, including mice, rabbits, moles, squirrels, groundhogs, and rats, as well as raccoons. Cats are probably the best means of rodent control. They stalk small prey, go after any movement, and are active at night, when most of these animals forage. Young plants are often protected from rodents by placing a coffee can with top and bottom removed around each plant. When the plants get bigger, they can be protected from rabbits and other animals with a wire fence three feet in height. A double layer of one-inch chicken wire is most effective. But many animals can climb or burrow; so more ingenious methods are needed to protect the plants. Rodents, especially moles, are repulsed by castor beans and castor oil. A formula that gardeners sometimes use is two parts castor oil, one part detergent, mixed to a consistency of shaving cream in a blender. Use a tablespoon of concentrate per gallon of water. Spray or mist the solution on the plants.

Rabbits shy away from blood, bloodmeal, and tankage. To use, sprinkle the powder around the perimeter of the plot in a band about a foot wide. They can also be mixed into a concentrated solution and applied as a spray. However, the small of blood may attract mongoose or other predators, which dig up the garden in search of flesh. Noise from radios, chimes, and bells deter some animals, and human smalls such as hair and urine may also deter some animals. In dry areas, a half-filled bucket of water is an effective rodent trap. The animals fall in and drown.

Deer seem to go out of their way to munch on tender marijuana leaves, but generally don't bother marijuana after it has grown for a few months. Gardeners and farmers use many ingenious techniques to keep them away from crops. Sturdy fences are the best deterrent. The fences should be about 10 feet high: the bottom five feet should be made up of single strands of wire string at two-foot intervals. The wire strands prevent deer from jumping the fence


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