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Sunday, December 20, 2009

Natural Weed and Insect Controls

Natural Weed and Insect Controls

By Blue Skye

I decided to find out a little about the history of weed and insect controls in the U.S. I also wanted to investigate some more about what kinds of natural weed and insect controls we can use, and how we can get away from using so many synthetic controls.

I discovered that Natural controls date back to the 1880’s when we imported the Vedalia Ladybug in mass to eradicate scale and mealy bugs in California. By 1950 we embraced synthetic chemical pesticides. Many reliable natural controls were dropped for this new found way of killing pests. By this time even research into natural controls halted at Universities across the country. In 1944 herbicides became an option with the introduction of 2, 4-D around the same time chemicals like chlorinated hydrocarbons DDT, aldrin, and dieldrin were taking over agricultural practices. The use of predators and parasites slowed down to almost nothing, because the new broad spectrum pesticides killed off everything including beneficial insects. Between 1945 to 1989 the pesticide use increased tenfold. This chemical use didn’t help win the war against pests. In fact during that time the populations actually grew from 7 to 13 percent. Over 500 species have developed resistances to pesticide. Now there are more than 600 active pesticide ingredients registered in the U.S. And 10% of them are know or suspected Carcinogens. Because of the awareness of these dangerous chemicals the Environmental Protection Agency was created in December of 1970. The registration of pesticides was then handed over to the EPA. The new awareness of pesticide poisoning our food and Environment triggered Integrated Pest Management.

Integrated Pest Management or IPM is an approach to pest management that helps prevent pest resistance of chemicals and helps reduce the killing of beneficial insects. Also by using IPM we can reduce our chemical use and the impact to our environment and health while restoring a balanced ecosystem. The basic components of IPM are first to ID the pest or disease as well as the host. Then you must monitor the activity and populations of the pest. Then determine the action threshold to decide if controls are necessary. You can then decide the methods of controls you are going to use whether it is a cultural, physical/mechanical, biological, genetics, chemicals, and finally regulations. A cultural control is to apply mulch, mow at the proper height cutting no more than 1/3 of the blade, pruning and crown thinning, seeding, fertilizing correctly. A Physical/Mechanical would be hand pulling or picking off insects and improving drainage. If you use a biological control you would use organisms to prey on or parasitize a pest using pheromones, nematodes, oil. When using genetics you might breed a plant to be resistant to pest or disease. The last is to us a natural or chemical control whether it is an organic or synthetic control like Iron or Sevin for Turf. Then if all others aren’t working a government agency may have to quarantine or make a plant a noxious weed to regulate it. After you have used a method or methods of control then you will need to evaluate your results. Recording and reviewing what worked and didn’t work so you can modify your IPM approach in the future.

Here are some good natural weed and pest controls. One form of natural pest control is; biological microbe’s bacteria, fungi, and other organisms that cause diseases that kill or cripple insect’s pests that are called microbial pesticides. The microbe most commonly used is the bacterium Bacillus thuringiensis or Bt. To be effective the pest must eat the Bt and it works by destroying the lining of their guts killing them within a few days. One of the benefits of Bt is it’s a very selective action it will only kill the caterpillars that eat it. There are different strains of Bt, that only certain pests are susceptible to it. For example, Btk kills gypsy moth, hornworms, and cabbage worms so most of the beneficial insects are spared from its effects.

Combining natural products like vegetable oils with an alkaline substance like potassium hydroxide make an insecticidal soap used for controlling mites and insects. Vegetable or refined petroleum can be a very effective treatment for pest. These horticultural oils smother insects by plugging the orifices, called spiracles, through which they breathe. The problem with oils is they can cause plant injury or phytotoxicity white flies, young scales, mites and some plants disease.
Insecticidal soaps work primarily by damaging the cell membranes of insects and mites. They affect aphids, leafhoppers, spider mites, and Japanese Beetles.

Nature has a way of controlling pest and disease on it own. For example, some plants have been proven to produce a chemical defense that is naturally resistant to the attack from many pests. Some plants like Ryania speciosa a native to South America which is extracted and used for insect control for codling moths and are called botanicals.

Ladybug adults and larvae increase in numbers to attack big aphid infestations. Other important predators include soldier bugs, spiders, damsel bugs, big eyed bugs, pirate bugs, assassin bugs, and syrphid flies, lacewings, and gall midges.

Using natural barriers act like barbed wire which keeps crawling pests, such as ants off plants. These barriers include garlic grinded up with water, cayenne pepper, cinnamon, powdered charcoal, bone meal, talcum powder or chalk. Each different kind of material will work best for different pests. One of the benefits of using these natural sources of weed and pest control is they have a wide range of effects and most do less ecological damage because they break down rapidly when exposed to heat, light, and water.

If your lawn and garden are healthy to start with then they will be more resistant to the effects of pests and disease. To keep your lawn in good shape you need to provide proper light, air, moisture, and nutrients. Provide good surface and subsurface drainage aerating and dethatching if necessary. Provide good air circulation and allow sunlight to penetrate. You want to make sure to choose the grass that is adapted to our area. You also want to not mow to short and only 1/3 of blade at a time so as not to stress the grass. If you remove too much of the food manufacture is drastically reduced resulting in poor root development. If possible when you do mow if you let the clipping say on the lawn it will provide more nitrogen improving the soil. When fertilizing using an organic fertilizer will prevent salt build up and allow for soil microbes to remain. Also when you irrigate you need to water in longer few intervals instead of everyday for a short time.

In conclusion, there are many ways to treat pests and diseases and if we use Integrated Pest Management, common sense, good routine landscape maintenance, and particular applications we can keep a good handle on pests without harming ourselves and our environment to so much. Sometimes all it takes is to learn what the best approach is and to teach it to others to make a change in common practices for the better like using more natural or organic materials with less ill effects.

Vinie, Erin “Natural Born Pest Killer: Home Remedies for Pest Control” Visited 6-1-07 2006

Yepsen, Roger Editor “The Encyclopedia of Natural Insect and Disease Control 1976.

Schultz, Warren Editor “Brooklyn Botanic Garden Natural Insect Control: The Ecological Gardener’s Guide to Foiling Pests” 1994.

Pleasant, Barbara “The Gardener’s Weed Book: Earth-Safe Controls” 1996.

Lecture by Steven Price at Portland Community College Spring 2007

Lecture by Marilyn Alexander at Portland Community College Spring 2007

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