Post by Ask Jan on Nov 13, 2011 17:41:19 GMT -8
lady bug and hoverfly
This article is about pests -- the organisms that cause injury, not disease. The pests described in this second part include arthropods, mollusks, birds, and mammals. Some of these pests predominate in fiber crops, others prevail in crops raised for seeds or flowering tops. Some are specific to Cannabis, others are general feeders. . Some pests have many natural enemies so they only cause problems indoors under artificial lights, other pests cause problems anywhere.
Cannabis has a reputation for being pest-free. Actually, it is pest-tolerant. Many pests have been found around Cannabis, but they rarely cause economic damage. The most common pests are arthropods.
Six arthropod classes are particularly important to Cannabis agriculture: the Crustacea (including "pillbugs," with 5-7 pairs of legs), Symphyla ("garden centipedes," with 12 pairs of legs), Chilopoda (true centipedes, with 1 pair of legs per segment), Diplopoda (millipedes, "thousand-leggers," with 2 pairs of legs per segment and many segments), Arachnida (spiders and mites, with 4 pairs of legs), and the Class Insecta, with 3 pairs of legs.
Insects are the largest class. Twenty-seven orders of insects are currently recognized by entomologists, and half of them attack Cannabis. Mostafa and Messenger (1972) list 272 species of insects and mites associated with Cannabis! Of course, few of these species elicit serious concern. Probably the worst pests are stem-boring caterpillars, especially in fiber crops. Two economically important pests are the European corn borer (Ostrinia nubilalis), and the hemp borer (Grapholita delineana).
European corn borers (ECBs) attract a lot of scientific attention thanks to their amazing appetite for corn plants. ECBs are native to eastern Europe, where Cannabis sativa and Humulus lupulus (hops) served as original host plants. ECBs switched to maize after Zea mays cultivation began in Europe two centuries ago (Nagy 1976, 1986). About one century ago ECBs moved to North America and plagued American hemp, where they "nourished themselves upon the marrow within stalks" (Dodge 1898). More recently ECBs have infested marijuana crops (Bush Doctor 1987).
ECB feeding induces stem cankers, which are structurally weak. Stems supporting heavily flowering tops often break at cankers. Larvae boring into smaller branches cause wilting of distal plant parts. Under heavy infestations entire plants collapse. Emchuk (1937) states five to twelve larvae can destroy a hemp plant. ECB entry holes in stems are essentially open wounds, providing access for fungi such as Macrophomina phaseolina. Other insects may also crawl in. ECBs hatching late in the season may infest flowering tops instead of stems, where they spin webs and scatter feces.
Hemp borers (HBs) are smaller than ECBs. HBs cause similar stem damage and are much more destructive in flowering tops. HBs are also called hemp leaf rollers and hemp seed eaters. In Russia, HBs have destroyed eighty percent of a crop's flowering tops (Kryachko et al. 1965). Bes (1974) reports forty one percent seed losses in unprotected Yugoslavian hemp. Each larva consumes an average of sixteen cannabis seeds (Smith and Haney 1973). HBs appear host-specific on cannabis (Mushtaque et al. 1973), so they have attracted attention as potential biocontrol agents against marijuana. Baloch et al. (1974) determined that forty larvae will kill a Cannabis seedling (15-25 cm tall) in ten days. As little as ten larvae per plant cripple growth and seed production.
Other Cannabis caterpillars feed as stem borers (e.g., Cossus cossus, Zeuzera multistrigata, Papaipema nebris, P. cataphracta, and Endocylyta excrescens). Some caterpillars spoil leaves, seeds, and flowering tops (e.g., Mamestra brassicae, Autographa gamma, Melanchra persicariae, Spilosoma obliqua, Arctia caja, and Loxostege sticticalis). However, few caterpillars cause as much damage as ECBs and HBs. An exception is the budworm (e.g., Heliothis armigera and Heliothis viriplaca). Budworms wreck havoc on flowering buds, but leave stems alone.
Other insects may also bore into stems. Examples include the grubs of flea beetles (Phyllotreta nemorum), tumbling flower beetles (Mordellistena micans and M. parvula), longhorn beetles (Thyestes gebleri), weevils (Ceutorhynchus rapae and Rhinocus pericarpius), and the maggots of gall midges (Melanogromyza urticivora).
Beetle grubs and midge maggots also bore into roots and leaves. The former includes the hemp flea beetle (Psylliodes attenuata), a serious pest in eastern Europe and China (Angelova 1968). The latter are called "leaf miners." Some leaf miners are beetle grubs (e.g., Phyllotreta nemorum), but most are tiny maggots (e.g., Liriomyza strigata, L. eupatorii, L. cannabis, Phytomyza horticola, Agromyza reptans).
The most serious root pests are flea beetle grubs (Psylliodes attenuata) and white root grubs -- Japanese beetles (Popillia japonica) and chafers (Melolontha hippocastani and M. melolontha). Minor root pests include root maggots (Delia platura), ants (Solenopsis geminata), termites (Odontotermes obesus), fungus gnats (Bradysia sp.), and wireworms (Agriotes lineatus).
Seedling pests can completely annihilate a young crop before it makes a stand. Cutworms are the most common. There are many -- the black cutworm (Agrotis ipsilon), paddy cutworm (Spodoptera litura), beet armyworm (S. exigua), claybacked cutworm (A. gladiaria), common cutworm (A. segetum), and cabbage moth (Mamestra brassicae). Crickets may also cut down young seedlings. The worst are field crickets, Gryllus desertus and Gryllus chinensis, followed by house crickets (Acheta domesticus), and mole crickets (Gryllotalpa gryllotalpa).
All the insects discussed above are distinguished by chewing mouthparts.
Marijuana crops are also frequently damaged by piercing-sucking insects. Perhaps the stylet used by piercing-sucking insects enables them to bypass toxins on the leaf surface, so they can suck up sap from within the plant. Cannabinoids are produced in surface glands and possess insecticidal properties (Rothschild et al. 1977). These insecticidal properties have long been recognized and utilized, especially in India. Cannabis leaves have been scattered in grain bins to repel weevils (MacIndoo and Stevers 1924, Khare et al. 1974), and placed under mattresses to drive off bedbugs (Chopra et al. 1941). Kashyap et al. (1992) protected piles of potatos for up to one hundred and twenty days by coating them with a layer of Cannabis leaves. Sprays made from hemp leaves kill many insect pests (Bouquet 1950, Reznik and Imby 1965, Stratii 1976, Fenili and Pegazzano 1974, Bajpai and Sharma 1992, Jalees et al. 1993).
If Cannabis is so insecticidal, then how do insects eating it survive? Perhaps they interspace marijuana meals with less-toxic feeding on other plants. Spilosoma obliqua, for instance, often eats Cannabis leaves and flowering tops (Nair and Ponnappa 1974). But when Deshmukh et al. (1979) force-fed S. obliqua caterpillars a pure Cannabis diet, they died after twenty days. Rothschild et al. (1977) conducted interesting experiments with tiger moths (Arctia caja). Tiger moth caterpillars, like monarch butterfly caterpillars, feed on poisonous plants and store plant poisons in their exoskeleton. The stored poisons repel predators of the caterpillars. But THC stunted caterpillar growth, and a high-THC diet killed caterpillars. Nevertheless, Tiger moth caterpillars preferred eating deadly high-THC varieties to low-THC plants. Rothschild notes, "Should these compounds [THC] exert a fatal fascination for tiger caterpillars, it suggests another subtle system of insect control by plants."
The most common pests of high-THC plants are insects with piercing-sucking mouth parts, ostensibly enabling them to bypass surface cannabinoids. Many piercing-sucking insects also do well in greenhouses under artificial light, such as aphids, whiteflies, leafhoppers, mealybugs, scales, and true bugs.
Spider mites, while not insects, also suck plant sap, and are the most destructive pests of greenhouse-grown (indoor) Cannabis (Bush Doctor 1986). Outdoor crops may also become infested in warm climates -- Cherian (1932) reports fifty percent losses in field crops near Madras, southern India. Two species are the worst: the two spotted spider mite (Tetranychus urticae) and the carmine spider mite (T. cinnabarinus). T. urticae and T. cinnabarinus are similar in appearance, in life cycle, and fecundity, but T. urticae thrives in cooler temperatures than T. cinnabarinus. The latter species only causes problems in semi-tropical zones with temperatures above thirty four degrees C. The hemp russet mite (Aculops cannabicola) is equally destructive, but less commonly encountered. Other mites cited on marijuana include the oriental mite (Eutetranychus orientalis), privet mites (Brevipalpus obovatus and B. rugulosus), and Typhlodromus cannabis.
Six species of aphids ("plant lice") cause Cannabis problems (Bush Doctor 1985). Some are fairly specific feeders, such as the bhang aphid (Phorodon cannabis) and hops aphid (P. humuli). Others are general feeders, such as the green peach aphid (Myzus persicae) and black bean aphid (Aphis fabae). Aphids congregate on the underside of leaves. They cause leaf wilting and yellowing. Entire plants may wilt and die. Any survivors are stunted. Some aphids also infest flowering tops, which become distorted and hypertrophied. As an aphid feeds, it exudes small drops of a sugary sap from its anus. This "honeydew" causes secondary problems--it attracts ants and can support a heavy growth of black sooty mold. Besides feeding damage, aphids also spread plant diseases. They vector viruses, bacteria and fungi from diseased plants to healthy plants as they feed and migrate.
Whiteflies cause similar problems (Bush Doctor 1985). The greenhouse whitefly (Trialeurodes vaporariorum), sweetpotato (or tobacco) whitefly (Bemisia tabaci), and silverleaf whitefly (Bemisia argentifolii) are vexing pests. Leafhoppers and mealybugs can also become serious pests, especially the glasshouse leafhopper (Zygina pallidifrons) and the long-tailed mealybug (Pseudococcus longispinus).
True bugs, like the Homopterans (aphids, leafhoppers, whiteflies), have piercing-sucking mouthparts and feed on plant sap. They feed predominately on leaves, but also suck on stems, flowering tops, and unripe seeds. Bugs, unlike most Homopterans, are outdoor problems. The southern green stink bug (Nezara viridula) feeds on marijuana in India (Cherian 1932), hemp leaves in Europe (Sorauer 1958) and hemp seeds in the USA (Hartowicz et al. 1971). Other examples include the tarnished plant bug (Lygus lineolaris), false chinch bug (Nysius ericae), and potato bug (Calocoris norvegicus). Liocoris tripustulatus has become an emergent pest in the Netherlands, where it feeds on pollen.
Thrips are becoming a problem in modern greenhouses that use rockwool and hydroponics. In old soil-floored greenhouses, damp conditions encouraged the growth of Entomophthora thripidum, a soil fungus which infects and kills thrips when they drop to the ground to pupate. Now, with soilless growhouses, there is no damp soil and, therefore, no fungus to act as a natural biocontrol. Pests include the greenhouse thrips (Heliothrips haemorrhoidalis), western flower thrips (Frankliniella occidentalis), and onion thrips (Thrips tabaci). These are all general feeders. Oxythrips cannabensis is specific to Cannabis, but is rarely encountered (Bush Doctor 1989).
Non-arthropods are minor pests compared with insects and mites. Mollusks, such as slugs and snails, may cause horrific damage to seedlings in damp and cool bioregions (such as the northwestern and northeastern US). Slugs cut down seedlings and shred leaves of older plants.
Birds devour Cannabis seeds. Early reports from Kentucky describe the passenger pigeon (Ectopistes migratorius) feeding on hemp seeds (Allen 1908). McClure (1943) ranks wild hempseed as the most important food of mourning doves (Zenaidura macroura) in Iowa. Captive doves thrive for long periods of time on hemp alone. Bobwhite quail (Colinus virginianus) and ringtail pheasant (Phasianus colchicus) depend on wild hempseed in the American midwest (Hartowicz and Eaton 1971). The dependence of these game birds on wild hemp has led wildlife agencies to oppose police eradicating wild hemp (Vance 1971).
Birds were the most serious pest problem in the recent cultivation of hemp by the Hempstead Company in the Imperial Valley, and substantial losses have recently been registered in Tasmania (Lisson and Mendham 1995). Sorauer (1958) cites many seed-eating European birds, including the hemp linnet (Carduelis cannabina), magpie (Pica pica), starling (Sturnus vulgaris), common purple grackle (Quiscalus quiscula), tree sparrow (Passer montanus), English sparrow (P. domesticas), nuthatch (Sitta europaea), lesser spotted woodpecker (Dendrocopus minor), and turtledove (Streptopelia turtur).
Mammals may cause crop damage. Some are domesticated -- Siegel (1989) describes cows and horses feeding on flowering tops in Hawaii. Duke (1985) recounts the loss of several horses and mules who gorged themselves on illicit Cannabis in Greece. Non-domesticated mammals cause more problems. Such pests include deer in the USA (Siegel 1989, Frank and Rosenthal 1978), monkeys in South America (Siegel 1989), and dik-dik in Kenya.
Hartowicz and Eaton (1971) found Kansas cottontails (Sylvilagus floridanus) feeding on wild hemp. Siegel (1989) cites raccoons (Procyon lotor) eating Cannabis. In Europe, Sorauer (1958) reports field voles (Microtus sp.) and hamsters (Cricetus cricetus) feeding on sown hemp seeds. Siegel (1989) mentions mice breaking into San Francisco police vaults to feed on seeds in confiscated marijuana! Alexander (1984) describes mice eating young sprouts, and groundhogs ("woodchucks"), gophers, moles and voles destroying roots. Groundhogs can also quickly destroy a young Cannabis stand by feeding on some plants and rolling themselves around in the rest. Siegel (1989) adds Rattus rattus to this list. Rats kill plants by stripping bark from stems to build nests. In Western Europe, pre-adult Homo sapiens who confuse fiber hemp for marijuana are a notable pest (Van der Werf 1996).
Common Cannabis pests
Seed & Seedling
Flower & Leaf (outdoor)
Flower & Leaf (indoor)
Stalk & Stem
hemp flea beetle
European corn borers
hemp flea beetle
white root grubs
hemp flea beetle
termites & ants
green stink bugs
Preventing These Mammals and Rodents
Most mammals and rodents can easily be avoided with a three foot tall chicken wire fence that stands around the plant or plants. A double layer is the most effective. The two main types of repellents are contact and area. Contact repellents are applied directly to the plant and have an undesirable taste. Some are made of rotten eggs or cayenne pepper. Area repellents are placed close to the plant and repel by smell alone. Cougar urine is great for deterring deer. A bag of human hair and bars of soap both work well for awhile. Another form of prevention is to scare the pests off with propane cannons or any loud noise that goes off on a regular interval. Even fireworks or gunshots. Motion sensor strobe lights will work well for a short time as well.
HOME MADE REMEDIES FOR PESTS-
Neem oil - Fights most predators including cucumber beetles, aphids, spider mites, and more.
Companion planting (outdoors) of Pyrethrum , Marigolds, Gopher plant, etc.
Finely chop one onion and two medium cloves of garlic. Put in a blender with 2 cups of water on high. Strain the pulp and pour the mixture into a spray bottle. Mist the plants making sure to coat both the top and bottom of the leaves at least half of an hour before the lights come back on. Good repellent for most pests (especially aphids).
A spray bottle filled with soapy water using six drops/quart to be sprayed on the bottom of the leaves. This will clog most insects breathing organs and will kill them. Use before you see any insects.
Fatty acid salts or insecticidal soaps are very good against aphids. They apparently work to disrupt insect cell membranes. They require direct contact with the insects and leave no residual effect.
Nervous system insecticides, such as malathion, Dursban (chlorpyrifos), and Orthene (acephate), are labeled for use on many shade trees and ornamental plants for aphid control.
Take a copious amount (as many as you can collect) of the insect you wish to repel and grind up their bodies. Mix the resulting mess with one quart of water and spray as a repellent for the insect that you wish to repel.
A bleach water solution: 10 parts water to 1 part bleach (water temp. 95 degrees) in a spray bottle is great for misting the leaves (kills spider mites)and most other pests it reaches.
Mix one eighth of a cup of hydrated lime with one quart of water. This creates an effective spray against many insects, especially spider mites. Add a drop of non-detergent soap (Bonner’s peppermint) to act as a sticking agent and insecticide. Lime can cause serious harm to plants if you use too much, so always spray a test plant first and watch it for a few days, to check for any adverse effects on plants.
Flypaper is very effective in the garden for aphids and white flies. Make your own sticky cards by using bright yellow paper coated with “TangleFoot” or any very sticky substance.
Pheromones: These biological mating scents attract insects to a pheromone treated trap which has also been treated with a sticky substance. Pheromone traps are effective, but remember they are "attracting" the insects. Make sure they are at the perimeter of your garden site.
Mix one whole egg with a quarter cup of water and mix well. Pour the mixture into a pump bottle and spray it on your plants. Or you can purchase egg powder, or you can purchase a small bag of sulfur. This deterrent will withstand light rains because the egg sticks to the leaves. This will stop the deer but only for a short while.
Mix one tablespoon of liquid dish detergent with one ounce of hot sauce in one liter of water and spray directly on plants. To stop deer.
For larger volume applications of the above remedy, mix the following ingredients and put them into a pump sprayer. Spray on plants.
1 cup milk
2 gallons water (8 liters)
2 whole eggs
2 tbsp. cooking oil
2 tbsp. liquid detergent
Larvae- Remove the top layer of soil from your pots. Water them with Neem Oil . Mixture: three tablespoons/ gallon of water. Flood plants. Replace the topsoil with fresh soil. To deal with the adults sprinkle powdered garlic on the soil. Yellow sticky traps work well. Place on top of the soil (in the pot) during the night. "No Pest Strips" placed in your grow room. Turn the fans off for one day only.
Indoor plant growers have always struggled to protect their plants from infections and pests. Most people are hesitant to use commercial pesticides because of fears about chemical residues left behind. This left them with few options and difficult choices.
Over the last few years, available options have expanded and improved. Many traditional pesticides have been reevaluated or reformulated - some have been dropped from use and others modified so that less is used. Currently, there is a lot of development in new pest control methods. Integrated pest management (IPM) is the new buzzword.
IPM can include new and re-discovered developments using non-toxic, ecologically-friendly chemicals, micro-organisms and insects for plant protection. Some industrial products have been scaled down to give home gardeners the tools once available only to large greenhouse growers. Organic and hydroponic growers both face the task of replacing or cleaning their growing medium after each crop. Usually potting mixes and rockwool are replaced, while clay pebbles are washed. These measures are taken to prevent the spread of disease across generations.
Several newer chemicals for greenhouse and grow room sterilization don't pose the same types of environmental or toxicity problems as older pesticides or chlorine. Here are a few examples of current sterilizing and pest control methods. All of the products described below can be used on fruit and vegetable crops and are compatible with organic gardens.
• ELECTRIC SOIL STERILIZER: This unit holds a cubic foot (about 7.5 gallons) of soil or other planting medium. It works using heat controlled by a thermostat ranging between 100 and 200 degrees. At 160 degrees, the material is pasteurized, killing most of the harmful organisms and as few of the beneficials as possible. At 180 degrees, the medium is largely sterile, killing most organisms and weeds. Sterilization takes about 30 minutes from the time you load the sterilizer. Rated at: 500 watts or 4 1/2 amps. Weight: 27 lbs. Approximate cost: $280.
• PHYSAN 20 (TM): This is a broad spectrum disinfectant made from a salt, double quaternary ammonium chloride. It leaves no residue and breaks down into nitrogen, which plants use. It can be used as a soil drench and to sterilize trays, walls and equipment. It can also help prevent seedling and plant diseases when added to the irrigation water. Physan 20 has been used for over 25 years and is generally considered very safe.
Physan 20 can be used in the same way as ZETOL (see next item). It is excellent for clean up between crops, sterilizing irrigation water and spraying on plants to kill pathogens.
ZETOL (TM): This can be used as a one-time soil sterilizer or as a water additive to keep the water sterile. It is a solution of hydrogen dioxide, a very powerful oxidant. When this chemical comes in contact with insects, eggs, bacteria and viruses, it oxidizes them. It can be used as a wipedown for trays and walls or any other pathogen-containing surface. It sterilizes used soil and other planting mediums when used as a drench.
ZETOL cannot be used with any of the biologicals mentioned below but is convenient to use instead of bleach or hydrogen peroxide for sterilizing equipment and medium before planting. It takes about 2 days to degrade to water and oxygen.
The ZETOL (TM) people use the sterilization approach for plant protection. Rather than using friendly organisms, they keep the water and plant surfaces pathogen free by adding small amounts to all irrigation water.
The pests most likely to attack indoor marijuana plants are aphids, fungus gnats, mites, thrips and whiteflies. Outdoor plants are subject to hungry rabbits, deer, rodents, caterpillars, slugs and snails as well as insects. Organic growers have an arsenal of beneficial insects to choose from. Here are some of the pests and their controls:
CONTROL: Aphidius colemani is a tiny parasitic wasp, which lays it eggs in living aphids. The adult wasp emerges from the aphid's body in two weeks, ready to mate and start reproducing. Aphidius colemani prefers temperatures below 80 degrees. One introduction to your garden is all that is required..
SOURCE: IPM Labs, 315-497-2063, E-mail: email@example.com
CONTROL: Aphidoletes aphidimyza is a predatory midge. The midge will lay about 250 eggs over a ten-day period near an aphid colony. The bright orange larvae, about 1/10" long, will eat about 10 aphids a day but attack many more. The larvae then mature in the soil, emerging as adults to lay eggs. The total cycle takes about 3 weeks. One release of 250 midges is enough to get a colony started. The insect lies dormant during flowering (12 or fewer light hours). Note: Aphidoletes aphidimyza don't do well in a hydroponic medium.
1) IPM Labs, 315-497-2063, E-mail: firstname.lastname@example.org
2) At Nature's Control, Nature's Control, P.O. Box 35, Medford, OR 97501. 541-899-8318.
CONTROL: Aphidius matricariae is a small predatory wasp that lays its eggs in aphid pupae. The adult wasp emerges from the mummified aphid larvae ready to destroy 200-300 aphids. Life cycle is about 3 weeks. This insect does not provide total control but works well against aphids. Recommended use is one parasite per 3 square feet. One release will start the colony. Outdoors, the recommended release rate is about 5,000 per acre..
SOURCE: Nature's Control, P. O. Box 35, Medford, OR 97501. 541-899-8318
CONTROL: Gnatrol (TM) is a strain of Bacillus thuringiensis , which attacks only fungus gnats. The bacteria are mixed in water and applied to the medium three times a week. The bacterium kill the larvae so the gnats are eliminated over several weeks..
SOURCE: IPM Labs, 315-497-2063. E-mail: email@example.com
CONTROL: Nemasys (TM) is a strain of predatory nematodes, which attack gnats in the larval stage. One pack of 50 million nematodes covers an area of 3,600 square feet. The nematodes should be introduced weekly for 3 consecutive weeks to eliminate gnat infestations.
SOURCE: Bioscape, Inc., 4381 Bodega Ave. Petaluma, CA 94952. 707-781-9233. www.bioscape.com.
CONTROL: Scanmask (TM) is Steinernema feltros , a hybrid strain of nematodes that use chemical cues to find their prey. The nematodes enter the insect and release bacteria that kill them. Scanmask is available both as a spray (to be used as a drench) and in granular form to be mixed into your planting medium. One application is all that is needed..
SOURCE: IPM Labs, 315-497-2063. E-mail: firstname.lastname@example.org.
CONTROL: Spider mites can be controlled by Stethorus punctillum , a type of tiny ladybug that eats both eggs and newly hatched spider mites. Each bug eats about 40 mites a day as well as many eggs. About 100 bugs are needed to start a healthy colony.
SOURCE: Nature's Control, POB 35, Medford, OR 97501. 541-899-8318.
CONTROL: Orius insidiosus, a minute pirate bug, is a small insect that dines on thrips. They reproduce quickly (every 10-20 days) and will decimate the adult population.
1) IPM Labs, 315-497-2063. E-mail: email@example.com.
2) Nature's Control, POB 35, Medford, OR 97501. 541-899-8318.
CONTROL: Encarsia formosa is a tiny wasp, which feeds exclusively on whiteflies. The adult female lays hundreds of eggs. In approximately 3 weeks the adult whitefly emerges, ready to eat and start laying eggs. These wasps are very effective but go into dormancy under a flower-forcing regimen. Weekly introductions for 3-6 weeks are suggested at first sign of infestation.
1) IPM Labs, 315-497-2063. E-mail: firstname.lastname@example.org.
2) Nature's Control, POB 35, Medford, OR 97501. 541-899-8318.
CONTROL: Delphastus pusillus is a tiny black ladybug, about 1/32" long that eats all stages of whitefly. Each beetle eats about 150 eggs daily and they can quickly control a whitefly infestation. Only one introduction should be required.
SOURCE: IPM Labs, 315-497-2063. E-mail: email@example.com.
GENERAL INSECT CONTROL:
Steinernema feltiae and Heterorhabditis heliothedis are two species of tiny worms known as predatory nematodes. They attack and kill almost all soil dwelling insects. The purveyor recommends re-inoculation every 6 weeks, but the pest problem is usually solved with one introduction. Some gardeners use predatory nematodes to attack foliage pests, but I don't find this very effective. The worms come on a sponge and treat up to 2,500 square feet. They are released into water from the sponge and then sprayed, watered or irrigated into the medium. One million nematodes costs about $16.
SOURCE: Nature's Control, POB 35, Medford, OR 97501, Tel. 541-899-8318.
CONTROL: Snails and slugs can be controlled using Sluggo (TM), a new environmentally friendly blend of bait and iron phosphate. The snails are attracted to the bait. They stop feeding immediately and die with a few days. The active ingredient, iron phosphate, decomposes naturally in the soil. Two pounds will cover about 5,000 square feet.
SOURCE: Available from Bioscape, Inc., 4381 Bodega Ave. Petaluma, CA 94952.
During a four-year study at Rutgers University, researchers found that Deer Off (TM) was the, "most effective preparation for deterring deer..." The product also deters squirrels and rabbits. The product is EPA approved and praised by environmentalists.
The spray deters predators through negative reinforcement. Made from eggs, hot pepper and garlic, predators find it both smells and tastes bad. It is non-toxic to humans, pets and the environment. One application lasts several months and is not washed away by rain.
SOURCE: Deer Off, Inc., 1127 High Ridge Rd., Suite 204, Stamford, CT 06905.
BETTER GROWTH AND DISEASE PROTECTION:
Gardeners have an arsenal of friendly microbes they can use to protect their crops from pests and disease. These organisms use the plant pests as their food source and quickly dispose of the problem. Their diet does not include larger organisms so they are completely harmless to humans and pets. Many of these products are used to prevent disease rather than cure it. They acts somewhat like a vaccine by attacking invading disease organisms.
Plants live in a symbiotic relationship with certain bacteria and fungi. These organisms promote plant growth by making nutrients more available to the plant. They also often serve as plant protectors by blocking sites that pathogens would use to attack. Some of the microorganisms actively attack pathogens. These are all registered for organic gardening use. Using living organisms to keep other organisms under control is the keystone of IPM.
• BIO-PLEX is a liquid bio-stimulant consisting of vitamins, enzymes, hormones, micronutrients and growth regulators. It encourages root growth and plant vigor. It is combination of ingredients include a combination of fish and kelp, Ascophyllum nodosum, cold-processed kelp, humic acids, chelated iron, zinc, and a soil and tissue penetrant. The manufacturer claims that this is a superior product because the penetrant allows the nutrient to be absorbed more easily and quickly by the plant.
The result is plants with more resistance to stress and disease and an environment at the root level that encourages the growth of beneficial microbes. It allows more efficient absorption of nutrients so less fertilizer is required..
Manufactured by Turf Chemicals Plus, Inc., 2213 Huber Dr., Manheim, PA 17545. 800-441-3573.
• ECO SANE (TM) is an "enzymic activated stabilized biologic catalyst". It promotes increased plant growth and crop yield, as well increased tolerance to stress, especially in cold conditions. It has increased production on many crops from 20 to 500% when used every 2 to 4 weeks. Working directly on the plant, it promotes beneficial microorganisms. One ounce in 2 or 3 gallons of water treats about 1000 square feet..
The EKMA (TM) Companies, POB 560186, Miami, FL 33256. 305-256-5456.
• MAXICROP is a product made from Ascophyllum nodosum, Norwegian kelp. Kelp contains large amounts of trace elements as well as hormones, enzymes and sugars that act as stimulants, encouraging plant growth and health. In addition to working directly on the plant, it encourages beneficial microbial life. Supplementing with Maxicrop results in stronger, more stress-resistant plants. The enzymes encourage stronger root growth and more vigorous leaf growth. The supplement is added to the water periodically.
Maxicrop USA, Inc., POB 964, Arlington Heights, IL 60006. 800-535-7964. www.maxicrop.com.
• MYCOR FLOWER SAVER (TM) is a mix of four strains of vesicular-arbuscular mycorrhizal fungi and growth-promoting bacteria with organic biostimulants. The fungi develop a symbiotic relationship with the roots providing them with nutrients in return for sugars produced by the plant. This relationship promotes faster growth and enhanced resistance to stress and pathogens.
The dry powder is mixed into the medium at the rate of 3 lbs. per 100 square feet at planting and can be used indoors or out..
Plant Health Care, Inc. 800 421-9051. www.planthealthcare.com.
• PHC BIOPAK (TM) is a biostimulant containing several strains of bacteria which develop symbiotically with the roots. They promote fast feeder root development, which increases plant growth, uptake of fertilizer and bio-activity in the medium; reducing susceptibility to disease.
Plant Health Care, Inc. 800 421-9051. www.planthealthcare.com.
• PHC HEALTHY START 3-4-3 (TM) is a fertilizer derived from bone, blood and kelp meal, rice bran and other natural fertilizers. The formula, 3-4-3, is a good mix for starts and clones as it promotes rooting. The natural ingredients provide complete micronutrients for soil and soilless media.
What makes this blend truly unique is the addition of nitrogen and phosphorous solubizing bacteria that make nutrients available to the roots as needed. Humic acid in the form of leonardite, a mined mineral, is added to encourage growth of beneficial microbes. Under these conditions, plants are less likely to suffer from nutrient deficiencies and require less fertilizer because nutrients are more efficiently delivered.
Can be used indoors or out.
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The first line of defense against insects and other plant invaders is to prevent them from getting started in the first place.
Indoor growers can achieve this by carefully filtering air intakes. Keeping the grow environment antiseptic clean. Outdoor growers have a harder time preventing insects from being in the environment , however, in the out of doors insects have a much bigger variety of plant life to choose from and may not choose your plants at all to attack.
All growers should examine plants daily with a magnifying glass, looking for insects and insect damage. Environmental sanitation is important; growers should maintain a pristine environment: remove all plant debris, use sterilized equipment, do not bring dogs into grow areas, make sure water and water reservoirs are disinfected, do not enter a grow area in the same clothes after visiting an infected grow area.
If spider mites establish themselves in a grow area, it is virtually impossible to get rid of them without removing all equipment and plants from the area and totally cleansing the space. Beneficial predatory mites placed on plants before spider mite infestations take hold can help defeat spider mites. Spraying mite-infested plants with organic soap, garlic, or cinnamide spray also kill mites. The use of toxic poisons on cannabis, at any stage in its growth cycle but especially during flowering, is dangerous to patient health and unethical.
Thrips can be controlled using predatory organisms and sprays, especially sprays containing pyrethrum, nicotinic acid, organic soap, and garlic. Thrips often rely on the grow medium for reproducing. Be sure to treat grow mediums as well as plants. Whiteflies are attracted to the color yellow; one control for whiteflies is a commercially available yellow card coated with sticky material that attracts whiteflies and then traps them.
Parasitic wasps released before whitefly infestation can keep whiteflies from taking over a grow situation. Sprays containing pyrethrum and organic gardening soap kill some whiteflies, especially when they are airborne. Whenever using sprays, be sure to spray the underside of leaves thoroughly, as this is where many pests live.
Fungus gnats thrive in overfertilized, over-watered grow mediums, especially those where organic fertilizer high in nitrogen has been used. Gnats can be killed by: disturbing the soil, heating the soil, predatory wasps, and applying: insecticidal soap, neem oil, rotenone, garlic oil, diatomaceous earth.
Budworms and caterpillars can be controlled by shaking plants several times a day to dislodge the insects. Then applying preventive sprays containing insecticidal soaps and/or organic toxins. Okay to use during the vegetative stage—not to be used during the budding stage.
It is usually best to watch for the gray mold-like symptoms of budworm and remove the bud or section of bud where the worm resides, rather than to risk spraying any kind of toxin on a bud.
New growers should bear in mind that pest attack symptoms can look exactly like those caused by nutrient disorders, overwatering, underwatering, overfeeding, pH fluctuation or heat stress. In fact, the 'bite mark' damage commonly associated with pest attack does not always occur. This is because instead of eating the plant, some pests will suck on the plant leaves, flowers, branches and stems.
In some pest attacks, the plant's leaves simply change color or curl. Leaf color changes or distortions like leaf curl are often associated with nutrient disorders or overfeeding, so before you make a nutrient disorder diagnosis you should examine your plants carefully for signs of pests. It is good practice to get in the habit of doing this anyway every time you check your plants. Carry a hand lens in your pocket at all times.
The main difference between a pest attack and a non-pest related disorder is the presence of the pests themselves. Since pest damage is highly variable you cannot rely on the damage alone to identify the pest. You need to find the pest, identify it and eradicate it.
In indoor spaces especially, acting quickly is critical. Try to commit the signs of infestation described in this section to memory, as this will help you to identify them quickly if you come across a pest attack in your grow. Remember though that not all insects are bad for your garden. Some experts make the mistake of listing pests that actually do not harm cannabis. Some of these insects instead prey on pests that you may want to get rid of.
Ants are small insects from the family Formicidae. They are usually wingless except during mating season. Ants are colony pests, are well known for their cooperativeness and industriousness and can destroy cannabis plants quickly. Ants eat cannabis leaves and carry portions of the plant back to the colony for food storage and construction. Ants are easy to spot because of their size, speed of movement and numbers. Along with leaf discoloration an ant-attacked plant may exhibit bite marks on the edges of the leaves. Ants also farm aphids, another type of pest that growers will want to eradicate. Ants can be removed using boric acid or any popular colony killer pesticide.
Aphids are small soft-bodied insects of the family Aphididae. Aphids are the single most common pest experienced by cannabis growers both indoors and out. They mainly live on plant juices by sucking sap from stems, branches and leaves. They are about 1/8 of an inch long and can be any color but yellow/green is most common. Some aphids have wings.
Aphids tend to secrete frothy or foamy waste material, called honeydew, around their feeding areas on the plant and are most likely to be found attacking new growth or the underside of leaves near a node region, but they can be anywhere. Aphids are generally surrounded by their young and they reproduce at an extremely rapid rate and spread quickly. In addition, some aphids transmit viral diseases. This pest must be eradicated from your grow as soon as possible.
Aphids are small and do not move very quickly so growers need to take extra care when checking their crops for aphids. Signs of infestation: stunted, curled leaves, ants. Aphids use piercing mouth parts to suck sap from the phloem. Aphid attacks cause leaf wilt. Ants often accompany aphids around (herding them and eating the “honeydew”).
Aphids can be removed from your grow using any pyrethrum-based insecticide. Spraying your plants with pyrethrum-based insecticide before flowering will help prevent future aphid attacks but a full spraying tends to cause a certain amount of plant stress and growth stunting. If you want to keep aphids out of your grow room, then you should spray down the grow room with a pyrethrum-based insecticide before introducing the plants to the environment, making sure that you cover the corners and door frame.
To treat a mild aphid problem, only spray the infected areas of the plant. An aphid attack on flowering plants can be a problem because spraying can damage the bud and separate your trichome glands from the cannabis flowers. Try to solve aphid problems before flowering at all costs. Chances are that if you have prevented an aphid attack before flowering then you should not get one during flowering unless aphid contaminated items are brought into the grow room.
A soapy pesticide like Safer's Soap can also be used to deter aphids. A mixture of dishwashing detergent in hot water can be used to clean down the grow room and by suffocating them. As stated in the introduction to this section, soap and detergents should not be used during the flowering period. Ladybugs are a natural predator of aphids and should be used to control them.
Cutworms, Caterpillars and Larvae
Insects that are in their early stages of development are problem pests because they are insatiable and will eat anything green that they can get their tiny mouths around. Their appetite is surreal when you actually discover how much a caterpillar can consume in a single day. One caterpillar can reduce an ounce cola to stem and stalk in less than four days. These pests pose a huge threat to your crop and must be stopped right away. Caterpillars especially like to eat young seedlings and new growth. They are also known to leave holes in leaf but other pests can do this too.
The only sure way to get rid of cutworms, caterpillar and larvae is to use a cutworm, caterpillar or larvae repellent. Usually the same product will affect all three pests. Cutworms can also be hand -picked from your grow. At night they sleep in a XC' shape in the soil or under the cover of a piece of wood or other debris.
Deer are so curious that even electric fences won't stop them over time. Deer will eat leaves, stems, flowers and branches. Damaged areas are usually large including complete topping of the main cola from the stem. There are much kinder ways to keep deer away from your crop. You need to get a hold of predator urine (cougar urine) from hunting shops. Find out which urine works best with deer to keep them away without attracting other plant-eating animals. Simply spray the urine on your patch and this will help keep the deer away. This method has a very high success rate at keeping deer from your grow.
Gnats are insects with long, thin fragile legs from the family Culicidae. Gnats can eat leaves but mostly suck sap from the phloem. The damage from a Gnat attack is similar to that of an aphid attack and can be treated in the same way: pyrethrum-based insecticide. Gnats cause less damage than aphids but need to be treated quickly nonetheless.
Generally harmless to cannabis unless they are found in large numbers, grasshoppers are insects from the Acrididae family with legs designed for jumping long distances. The males make a high pitch clicking sound.
There is a particular species of grasshoppers often called Mocusts'that form in large migratory swarms and are highly destructive to nearly every kind of vegetation. Locust attacks are so severe that they can strip a plant down to its stem and branches within a few hours. During a locust attack the grower can only take cuttings from his or her plant and continue the strain elsewhere. Locusts will even eat pesticide-laden plants when traveling in large numbers so pesticides are rarely effective against these types of attacks.
Grasshoppers are treated as tourists in small numbers. They stay around only for a short period of time and move on. Grasshoppers are best hand- picked from your plants if you wish to control them. Birds also eat grasshoppers.
Groundhogs are a burrowing colonial rodent of the genus Marmota. They eat the shoots and leaves of the cannabis plant. Dry chlorine helps keep groundhogs away from your plants. If you find any groundhog holes near your grow area, apply the dry chlorine around the hole.
Mealy bugs are insects from the Pseudococcidae family. They are often described by growers as hard aphids' because of a waxy powder that makes their backs look shell-like under a microscope. They attack plant tissue and suck sap from the phloem. Mealy bugs are treated in the same way as aphid attacks: using a pyrethrum-based insecticide.
Rabbits are burrowing plant-eating mammals of the Leporidae family. They can be recognized by their long ears and short fluffy tails. Rabbits are voracious eaters and can reduce a crop to nothing in a couple of days. They will continue to feed from the same patch until they are done or the patch is destroyed. The best way to keep rabbits from your grow is to use predator urine. Rabbits also shy away from cats and dogs.
Scale is closely related to the aphid and comes in several different forms. Scales are born mobile but will eventually solidify (at any plant location but mostly on the branch and stem) and insert a small hollow tube into the plant to tap into the juices. They also spread mold. Scale can be hand -picked from your plants with ease because, when they solidify, they stay on that area of the plant. Ants farm scale so ants need to be removed from your grow room before you treat a scale problem. Scale can also be scrubbed from the branches, using a scouring pad. Dormant oil sprays, a form of organic pest control, also kill scale. You should be able to obtain dormant oil from any good grow store.
Slugs and Snails
These pests are molluscs of the class Gastropoda and characteristically have a flattened ventral bottom that they use for movement. They eat the leaves and stem and will kill cannabis seedlings. Slugs and snails are best hand- picked from your grow area. Another way to remove them is to make a circle of table salt about four feet away from the base of your plants. Then make another circle a foot in from that. Salt is deadly to snails and slugs and will keep them out.
Always keep a bottle of pesticide that kills spider mites on hand because marijuana plants are extremely vulnerable to mite attacks. Spider mites can reduce your plants to garbage within a couple of days so you should never bring a plant inside that has been outside.
Spider mites are tiny, about half the size of this period. Spider mites cannot be seen without a magnifying aid but are normally spotted because they gather in large numbers to form clusters on areas of your plant. Spider mites feed off plant juices and leaf wilt is a common symptom of a mite attack. Leaves get a stippeling (silvery) look on them. If the attack continues the plant will eventually die. Spider mites spin webbing on the affected areas of the plant (colonizing).
Specialized spider mite pesticides like Avid will curb attacks. Sulfur also deters spider mites. Raising the humidity above fifty percent (indoor). Mites hate to be misted. Even if you just spray them off with cold, clear water. What mites love is a hot, dry, and dusty environment. During vegetative growth, spider mites can be exterminated using soaps. After aphids, spider mites are the second most common pest experienced by cannabis growers both indoors and out.
Termites are a type of Isoptera and live in colonies. Termites are very destructive, even in small numbers. They have the ability to chew through wood rapidly and can chop a plant at the base of its stem within a few days. Termites do not like water. If you overwater the soil around your plant, termites will leave but then you will be left with an overwatered (soggy) plant.
There are commercial products available that kill termites but most of these are not for plant use or human consumption. The best way to kill termites is to find the nest and flush it with water.
Thrips are a member of the Thysanoptera family and are minute dark-colored insects with slim bodies that have wings in adult form. They usually attack the flowering parts of the cannabis plant and suck juices from the leaves. Thrips infestations usually cause the cannabis flowers to fall apart and look silvery in patches. Thrips are not typically around for long because their natural predators are beetles, ladybirds, lacewing and mites. Thrip infestations can be treated with any good thrip pesticide or pyrethrum. Thrips also do not like garlic.
Whitefly are from the Aleyrodidae family and are usually about 4 mm in size, although there are more than 200 species of this insect vary in shape, size and color. One particular species even likes to spend its entire life within greenhouses — hence its name 'Greenhouse Whitefly'. Whitefly normally have waxy white wings and use these to fly over short distances. If you shake your plant you should be able to hear them before you see them. They make a buzzing sound when moving in small groups. The whitefly can be deadly to your crop and can reduce your plant to trash in days. They feed on plant juices and secrete a honeydew, which has the natural ability to develop a dark mold on the secreted areas. This mold will also affect your plants' health if left untreated.
Safer's Soap™ helps to kill whitefly and can be bought in most grow shops. Other soaps and sprays will also kill whitefly. The whitefly's natural predators are spiders, ladybirds and beetles. Yellow Pest tape can also be quite effective against whitefly. Whitefly are the third most common pest experienced by cannabis growers both indoors and out.
Woodchucks and Other Small Rodents
Woodchucks will nibble your stems and collapse the plant. The way to solve this is by either using predator urine (see also deer and groundhogs) or building a very small mesh fence around the base of your outdoor plants.This will keep the wood-chucks from eating your stems and branches. Use more than one layer of mesh and make sure that you keep it tight. Planting marigolds near your grow will also help keep the woodchucks away.
There are many predators of pests that, at first glance, may appear to be plant pests but will not actually damage your crop. You should keep these friendly pests around, since they are nature's way of eliminating many of the pests listed above. Beneficial pests can even be bred or bought so that you have a constant supply of these pest killers.
Ladybeetles (LadyBugs) will breed on their own if they have a constant supply of aphids and other insects to feed on. Many places stock pest predators. Contact your local agricultural supply store to find out where predatory pests might be available. There are companies out there that provide this service and will even send some predator pests by mail order.
Ground beetles are usually black, brown or have a bluish tint along with wings and solid covers that surround the wings on their backs. Beetles usually work best at ground level eradicating most types of snails, slugs, cutworms and other insect pests. They are usually found in soil or hiding under debris like rocks and wood.
Braconid wasps are from the hymenopterous family of insects. Their eggs actually act as a parasite on unwanted pests like aphids, scale, cutworms and other kinds of larvae. In most instances this occurs shortly after the wasp has injected several of the pests with its own eggs. Injected cutworms will eventually develop several microscopic cocoon-like pods on their back and sides. The braconid wasp larvae sucks the insect dry as it develops inside these cocoons.
Certain types of what gardeners refer to as 'true' bugs will curb unwanted pests. 'True' bugs will actually suck all the bodily fluids out of their victims. The assassin bug (red underside), big-eyed bugs (has big eyes), pirate bugs (checkered black and white or gray and brown) and damsel bugs (long and large front legs and are gray, brown or tan in color) are the most common true bugs you will find although there are many more. Pirate bugs are especially effective against spider mites and thrips. Bugs are usually more than one half inch in size and will move relatively quickly around your plant.
It is worth mentioning earthworms here even though they are not pest predators. Earthworms help to aerate your soil along with depositing nitrogen, calcium, phosphorus and potassium in the soil. One organic type of feeding product is called 'Worm Casting' and is mostly made from earthworm waste material. If you farm earthworms you can create your very own organic fertilizer.
Lacewings will eat aphids and spider mites. They are usually green with large semi-transparent wings that extend well past the length of their bodies. They have two long and thin protruding antenna from their heads, 2.5 cm in length and can be approached and handled without much difficulty.
Ladybirds or 'ladybugs' are amazing predator pests because they eat a lot of other insects that are damaging to cannabis. They eat aphids, mealy bugs, scales and spider mites. Ladybirds must eat aphids and other insects in order to lay eggs. The more they eat, the more eggs they lay. As a result, the amount of new ladybirds born is directly proportionate to the amount of pests they consume. One female ladybird can consume up to 4,000 aphids in a lifetime and lay 2,000 eggs as a result of this. Ladybirds are the cannabis grower's pest predator of choice.
Unfortunately a common garden-variety spider is not enough to prevent a pest attack from occurring in your crop. You need them in large numbers to prevent any damage and even then spiders are very slow in their work. They also tend to spin webs in places where you do not want them and are not very controllable — however one type of spider that flies is of enormous benefit to your grow and is easy to control. That spider is the common *daddy long legs' and will consume nearly any insect in your grow room. Because this spider flies, it is not restricted to building webs in awkward places nor is it likely to cover your bud with spindle fibers like other spiders do. Also, those with arachnophobia don't seem to mind this type of spider as much because they are not very vicious looking and are easy to spot.
RECOVERING FROM A PEST INVASION
Sometimes the pests win. No matter how much you might spray to control or kill them, they keep coming back to your grow area. To solve this you may have to create a clean room or simply find another path, which may mean a complete do over— you don't want to re-introduce any pests or diseases into your new crop.
If you are growing indoors, first set up another grow room of smaller size, just enough to support some cuttings and clones. Take cuttings from the plants you have and move the cuttings to that room. You will use the cuttings again eventually in your clean grow room if you want to continue those strains. Next, take all the grow equipment excluding the electrical equipment to the bathroom. Clean down all of the equipment with bleach. Fill a tub with water and bleach and allow the grow equipment to rest there for a day. Do not wash electrical equipment. Clean it down with a slightly damp cloth (bleach solution).
In the grow room, first start with the walls. Clean the walls down with bleach (10% solution) if possible. You may have to paint them (flat white is good). If you use Mylar — replace it. Do not neglect the corners and clean out any holes, crevices, pipe fittings, any place where pests can hide. Then clean around the rim of the room. If your floor can be lifted up then you can also do this to get at the corners a bit better. I always start by vacuming thoroughly, then I go to the actual cleaning. I have a small steam cleaner that I use too. Then I use the bleach solution almost everywhere. Be sure to wear clothes that can be thrown away. I get my bleach solution on every surface. I also flood the flooring with bleach solution. It takes several days for the room to dry out.
After this cleaning, smoke the room (set off a pesticide bomb). Various pest-killing smoke bombs can be bought in most grow stores. Follow the instructions carefully and smoke bomb the room. This will guarantee the demise of any bugs, eggs or larvae, but remember eggs can remain safe from these sprays. That is why the labels recommend a reapplication seven to ten days after the initial treatment. Once this is completed, clean the room as you did the first time. Repeat the process if needed. The more you clean it, the better it will be.
Next, your cuttings need to be checked for bugs. You will not move any plants back into the grow room until you have taken cuttings from these cuttings. Grow the cuttings out for a week or two and check them every day for bugs. If you find any then you may have to use a pesticide on the cuttings. When you are sure your cuttings are clean, take new cuttings and place them in a growing medium. Take these to your grow room and watch their progress, being wary of any signs of pests and bugs. If you have done this correctly you should have eliminated all pests in your grow room.
Spider mites and other small pests can lay their eggs in cuttings and can be missed when you look for pests, because they are not as obvious. The pesticides should have killed them but some pests, like powder bugs, lay their eggs inside the stem and seem to always come back. If you cannot get rid of bugs like these then you may have to toss your plants away and get new ones. For breeders this can be a difficult task. A long-term project can be terminated by a few bugs wreaking havoc in the grow room. Breeders should pay strict attention to maintaining the cleanest growing area possible. Remember, never take anything that has been outside into the grow room.
Using (IPM) Integrated Pest Management principles and practices sets the standard for how all growers should be conducting business.
IPM is an effective and environmentally sensitive approach to pest management that relies on a combination of common sense practices. IPM programs use current, comprehensive information on the life cycles of pests and their interaction with the environment. This information, in combination with available pest control methods, is used to manage pest damage by the most economical means, and with the least possible hazard to people, property, and the environment.
The IPM approach can be applied to both agricultural and non-agricultural settings, such as the home, garden, and workplace. IPM takes advantage of all appropriate pest management options including, but not limited to, the judicious use of pesticides. In contrast, organic food production applies many of the same concepts as IPM but limits the use of pesticides to those that are produced from natural sources, as opposed to synthetic chemicals.
1. How do IPM programs work?
IPM is not a single pest control method but, rather, a series of pest management evaluations, decisions and controls. In practicing IPM, growers who are aware of the potential for pest infestation follow a four-tiered approach. The four steps include:
o Set Action Thresholds
Before taking any pest control action, IPM first sets an action threshold, a point at which pest populations or environmental conditions indicate that pest control action must be taken. Sighting a single pest does not always mean control is needed. The level at which pests will either become an economic threat is critical to guide future pest control decisions.
o Monitor and Identify Pests
Not all insects, weeds, and other living organisms require control. Many organisms are innocuous, and some are even beneficial. IPM programs work to monitor for pests and identify them accurately, so that appropriate control decisions can be made in conjunction with action thresholds. This monitoring and identification removes the possibility that pesticides will be used when they are not really needed or that the wrong kind of pesticide will be used.
As a first line of pest control, IPM programs work to manage the crop, lawn, or indoor space to prevent pests from becoming a threat. In an agricultural crop, this may mean using cultural methods, such as rotating between different crops, selecting pest-resistant varieties, and planting pest-free rootstock. These control methods can be very effective and cost-efficient and present little to no risk to people or the environment.
Once monitoring, identification, and action thresholds indicate that pest control is required, and preventive methods are no longer effective or available, IPM programs then evaluate the proper control method both for effectiveness and risk. Effective, less risky pest controls are chosen first, including highly targeted chemicals, such as pheromones to disrupt pest mating, or mechanical control, such as trapping or weeding. If further monitoring, identifications and action thresholds indicate that less risky controls are not working, then additional pest control methods would be employed, such as targeted spraying of pesticides. Broadcast spraying of non-specific pesticides is a last resort.
Dr. Clark video:
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mite infestation aphids thrips white flies two-spotted spider mite