Thursday, June 16, 2011

Growing a healthy and pest free garden

Courtesy of Magnus Rosendahl
Humans have been bothered by bugs since the beginning of time and have been applying pesticides to purge these pesky problems for thousands of years. Going back to 2500 BC, we find the Sumerians using sulphur to control mites. Fast forward to 1000 BC and we read Homer’s writings about the use of sulfur to fumigate homes. And, speeding to 900 AD, we watch as the Chinese use arsenic to control garden pests.

This use of inorganic and biological substances continues as a way to control pests and diseases in gardens and homes.
Over the millennium, humans have learned how to use Paris green, lead arsenate, calcium arsenate, selenium compounds, lime sulfur, pyrethrum, thiram, mercury, copper sulfate, derris, and nicotine to control harmful insects and plant diseases. But, one thing can be said, humanity had the foresight to use these compounds in limited quantities. Handed down from generation to generation was the belief that cultural methods such as crop rotation, soil tilling, and planting crops around a pest’s life cycle to avoid devastation were saner methods of pest control

In the mid-20th century, synthetic pesticides found a foothold in agricultural practices. The first synthetic organochlorine, DDT (dichlorodiphenyl-trichloroethane), was discovered in 1939 and opened a Pandora’s Box of toxic chemicals. Other organochlorine insecticides followed:  benzene hexachloriade (BHC), chlordane, toxaphene, heptachlor, aldrin, dieldrin, endrin, endosulfan, and isobensan. These chemicals act on an insect’s nervous system causing malfunctions and tremors that bring about an insect’s eventual death.

After years of watching these toxins move up the food chain, countries started to ban these organochlorines from use in 1973. It was discovered that organochlorines are insoluble chemicals that persist in the soil. Eventually, they are absorbed by plants which are eaten by small critters which are consumed by larger predators. This dangerous and fatal cycle brought about the near elimination of many animal species and the increase of cancers in humans.

Worldwide, chemical pesticide use has blossomed. About 4.4 million tons of more than 1,600 pesticides are sprayed, scattered, and disbursed in homes, gardens, and fields around the globe.

In the early 1960s, a holistic approach to pest control was proposed. This concept, coined as Integrated Pest Management, was introduced by the US Academy of Sciences in 1969. Integrated pest management teaches that pest problems can be reduced by understanding a pest’s life cycle, determining a pest’s natural enemies, developing disease and pest resistant plants, and applying cultural and physical controls to pest eradication.

Researchers in Arizona use a mix of common
liquid dishwashing detergent and cooking oil
to kills sweetpotato whiteflies
Courtesy US Department of Agriculture
Integrated pest management adopted the philosophy used by home gardeners prior to the 1950’s when chemical pesticides and chemical fertilizers weren’t readily available. These gardeners believed that keeping the soil fertile, fostering beneficial insects, and practicing garden hygiene would create the ideal growing environment for healthy and nutritious vegetables. This doesn’t mean the elimination of pests. It means that damage from pests is kept to a minimum without using harmful pesticides and damaging the environment.

Integrated pest management is a relatively simple process once you get the hang of it. The first step is to keep your garden soil healthy. The second step is to monitor your garden on a daily basis. When you see plant damage, go to step three and identify the pest and become acquainted with their life cycle. Once you know your pests, the fourth step is to determine the best eradication method. With all that said and done, finish up with step five and keep the future in mind by scheduling plantings so that susceptible plants are not in season at the same time as the pest.
Step 1:  Compost, compost, compost

Fertility is an important element in pest management practices. Provide your garden with regular applications of compost. Compost has many advantages:
  • Keeps the soil rich with nutrients and reduces the chance that soil borne pests will make your garden a home.
  • Improves the texture of the garden soil so that plant roots can freely and easily grow.
  • Provides good drainage so that the soil will not become waterlogged and your plants will not develop rot or fungus.

Composting publications from the US EPA

Step 2:  Always be on the look-out

Monitoring may be one of the most important steps in the integrated pest management process. You should monitor your garden on a daily basis. Look for any damage to your plants and identify any harmful pests. In addition, assess the severity of the problem. Is it a major problem in need of immediate control or is it a minor problem that can be tolerated?

If you see a pest problem, immediately look for the culprit. There are many signs of pest problems:
  • Chewing on leaves or stems
  • Sucking the sap from leaves or fruits
  • Boring and tunneling in the bark or seeds
  • Laying eggs or attacking roots

Department of Entomology
Texas A&M University
Convergent lady beetles
Hippodamia convergens
Keep your eyes open for beneficial insects. It is important to understand that not all insects are harmful. Many are beneficial to your garden environment. Take care to foster insects that pollinate flowers, produce honey, attack harmful insects, provide a food source for fish and birds, and improve the soil.
Hugh A. Smith and John L. Capinera
University of Florida IFAS Extension

Step 3:  Know your pest

Before you can deal with a pest problem, know the type of pest you are dealing with, what stage in the pest’s life cycle is likely to cause the most damage, and what stage in the life cycle is the most susceptible to control measures.
eXtension Foundation

Step 4:  Choose your eradication method

Once the pest and the problem have been identified, select your control method. There are several controls available to the home gardener:
Silverleaf whitefly, Bemisia argentifolii
  • Cultural controls disrupt the normal life cycle of the pest. These methods include removing the affected plant, attracting the pest away from the affected plant, trapping pests, and tilling the soil to expose pests to an unfavorable environment. Crop rotation, sanitation, crop timing and mixed cropping will also deter pests from your garden.
  • Mechanical and physical controls manipulate the environment to remove unwanted pests. These methods may be as simple as hosing aphids off of plants or hand-picking caterpillars out of trees. Row covers can keep pests off of plants. Collars around seedlings can prevent cutworms. Sticky traps attract and trap insects. Light may confuse the nocturnal Chinese rose beetle.
  • Biological controls provide a hospitable habitat for beneficial insects and animals. Make a home for lady bugs, praying mantis, spiders, lizards and birds. These beneficial insects eat insect pests.
John R. Meyer
Department of Entomology
NC State University

Step 5:  Plan for the future

Another element of pest control is crop selection and rotation. Whenever possible, select seed varieties that are resistant to the pests found in your area. Also, by rotating the place in which you plant each vegetable variety, you avoid a build up of pests.

Crop Rotation for the Small Garden
By Carol Hancock
Extension Master Gardener Volunteer
NC State University Extension Office

Use pesticides as a last resort

Organic pesticides should only be used in the case of a serious infestation. But, if you have been keeping a close eye on your garden, you won’t need to resort to this extreme measure. If you do need to use an organic insecticide or pesticide in your garden, apply it only to the affect areas and be careful not to spray any beneficial insects. Also, even though a pesticide is organic, use it carefully. Always follow the directions on the label, use the proper equipment to apply the pesticide, and wear protective clothing.

Organic Gardening magazine

By keeping a close eye on your garden, you will ensure a plentiful and bountiful harvest all year long.

Happy Gardening!


  1. Great post! Thanks for all the references!

  2. Hi Sage Butterfly! Glad you liked the post and the references! Have a great day!

  3. Great post! I like the ref. too. My grandmother kept a garden all her life until she died at 94. She did use sevendust as a last resort and always by the label. She only spent five days in the hospital in all her life, her last five. Keep an eye out and act quick and soap and water always works for me. On my beans I have had to use dust once this year. I was overrun on nite. lol
    Again nice post!

  4. Very informative post. I do find the monitoring bit hard sometimes. By the time I see the pest eg gooseberry sawfly it's almost too late and they have defoliated the plant!