Chemicals -- The Last Resort
Chemicals
The last management practice and most harmful to the environment is the use of chemicals. This is the method of last resort. Unfortuanately, many people turn to systhetic chemical as the first method for problem management. Organic and synthetic chemicals are both powerful substances to be used with caution for specific reasons.
Chemical applications are organic or synthetic, contact or systemic. Herbicides, pesticides, fungicides, miticides are used to kill. "Cide" means "kill." Most “cides” are contact-type chemicals that are sprayed or applied on to the plant or into the air. Systemic pest controls are applied to leaves, stems or through the soil for the plants absorption into its system. One should not eat any plants, leaves flowers or vegetables that have taken in systemic insecticides. Likewise, one should not eat plants, leaves, flowers or vegetables that have been sprayed with chemicals. Be on the safe side (read the label carefully for full instructions).
Organic Chemicals
Organic “cides” are made from natural substances and break down quickly. Repeat applications may need to be made. Organic pesticide examples are insecticidal soaps, horticultural oils, and botanicals such as neem oil, sabadilla, rotenone, ryania, and pyrethrum (sometimes spelled pyrethrin).
Insecticidal soaps, such as Safer, are contact controls that work on soft-bodied insects like aphids and mites by drying their outer layer. They have minimal impact on beneficial insects.
Horticultural oils, or dormant oils, are generally applied in late winter and act by smothering the insects breathing pores, killing both the active and over wintering stages. Horticultural oils are contact controls and will also kill beneficials. Horticultural oils have been developed for summer use, and are lighter oil concentrations. To avoid premature leaf drop due to burn, do not apply oils and soaps often when temperatures are above 80º; that is, more than twice within a 7 day period. As with all substances designed to kill, follow label instructions carefully.
Twenty percent vinegar solution is an organic herbicide. There are other organic herbicides on the market as well; one new product introduced to the market last year is AllDown (www.sumrset.com). Some products are available locally. If you’re not able to find them, ask for them.
Before you turn to synthetic chemicals, consider using natural pest remedies. Study up on them, there are many books available today and many naturally based products (www.invisiblegardener.com, www.dirtdoctor.com, for example). Because many people now are choosing to live healthier lifestyles in their home and garden, the “Green Industry” is emerging, offering products that claim to be ecologically, environmentally friendly, previously referred to as organic. As with anything, the possibility for fraud exists. But there are sources consumers can access to help them in making informed, earth-friendly choices.
The Organic Materials Review Institute (OMRI) is a 501(c)(3) nonprofit organization that specializes in the review of substances for use in organic production, processing, and handling. OMRI conducts materials review according to the standards established with implementation of the USDA National Organic Program (NOP) in October 2002. Brand name review is conducted as a transparent, third party review of products intended for use in certified organic production, handling, and processing. After review by OMRI staff, applications are submitted to an independent Review Panel of experts who evaluate a product’s compliance with the NOP National List. Products that have passed review are included on the OMRI Brand Name Product List. The OMRI Listed™ seal, which these products can display on labels and in advertising and promotions, assures their suitability for use in certified organic production. (www.omri.org). Consumers and gardeners alike can access their website for additional information.
Keep in mind that natural or organic remedies also kill beneficials along with the problem insects or weeds. Follow directions carefully and in recommended concentrations only. The label is the law. The users of these products are responsible for any damage, including drift damage. Use hand held spray bottles to spot treat the area to minimize toxic effect. Spray only on calm, windless days. A small, disposable sponge craft brush comes in handy in painting on “cides” (organic or synthetic) among ornamentals and even vegetables in close quarters.
Synthetic Chemicals
Use synthetic pesticides, herbicides, miticides or fungicides as the last resort. Synthetic “cides” are made from chemical compounds not found in nature. Many have long-lasting residual effect; some have a shorter residual life. Over time, pests develop resistance to these synthetic substances and rebound even stronger. In addition, these synthetic compounds contribute or cause unintended and harmful environmental effects.
Use specific remedies for the problem in the most vulnerable stage of growth to the pest or invasive weed. Using these products require specific knowledge of the pest and/or pathogens. Some chemicals are broad spectrum; others target specific pathogens, pests or weeds. As with organic “cides”, follow directions carefully and in recommended concentrations only. The label is the law. The users of these products are responsible for any damage, including drift damage. Use hand held spray bottles to spot treat the area to minimize toxic effect. Spray only on calm, windless days. A small, disposable sponge craft brush comes in handy in painting on “cides” (organic or synthetic) among ornamentals and even vegetables in close quarters.
Beneficial insects, organisms and plants are affected adversely as well as the bad. Removing the bad insect, fungus and/or weed along with beneficials sometimes will give room for secondary problems to move in and multiply, thereby exchanging one problem for another.
Resistant insects develop as a result of an incomplete kill. For some reason, 100% eradication is never achieved. Some of the pests that remain have some resistant quality that prevents them from being killed. When these pests multiply, the chemical resistance is passed on to the young. Soon, a new pesticide resistant strain of pest is present, and without the normal predators to keep them in check.
In the rebound effect, pests usually recover quicker than the predators. Plant-feeding insects are at the bottom of the food chain and are therefore more numerous than their predators. Naturally this makes sense. It'll take many aphids to satisfy the hunger of an aphid predator, such as a lady beetle. If pesticides killed all aphids, this guaranteed meal to lady beetles would cease. But pesticides do not wipe out all aphids (or lady beetles either, although a good many of both are destroyed at the same time). The remaining aphids multiply faster than the lady beetles. Being lower on the food chain, aphids multiply faster and stronger and may even become genetically resistant. They now face fewer enemies. Using pesticides instead of using the less harmful method, such as spraying with a jet of water, has created a greater problem.
Insect interactions with other insects, both insect predators and plant predators are within the natural order of things. One feeds on the next, that feeds on the next, that feeds on the next and so on. Disruption by chemicals sets the community off balance.
References
- Ecology for Gardeners, Steven B. Carroll and Steve Salt, Timber Press, 2004.
- Insects and Gardens, In Pursuit of a Garden Ecology, Eric Grissell, Timber Press, 2001.
- IPM for Gardeners, A Guide to Integrated Pest Management, by Raymond A, Cloyd, Philip L. Nixon and Nancy R. Pataky, Timber Press, 2004.
- Master Gardener Handbook, edited by Douglas F. Welch and Samuel D. Cotner, Texas A & M Press, 1995, third edition.
- Silent Spring, Rachel Carson, Houghton Mifflin, 1962.