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You can reduce and deal with pest problems

For Release On Or After 05/30/14

By Dan Gill
LSU AgCenter Horticulturist

A wide variety of pests can damage plants or cause problems in Louisiana landscapes. They include insects, mites, fungi, bacteria, nematodes and a whole host of weeds.

One of the best defenses against pest problems is to keep your plants in tip-top condition through good culture. Vigorous, healthy plants may be more resistant to diseases, withstand insect attack better and suppress the growth of weeds. Good culture includes giving your plants proper spacing, soil, water, light and nutrients.

Another way to avoid pest problems is through selection. Simply do not plant those varieties that are known to be prone to insect or disease problems. Check references or talk to knowledgeable horticulturists and ask about any major insect or disease problems with a plant you are considering for your landscape.

Choose plants that are well-adapted to our climate and not prone to major problems, or those which have been bred and selected for insect and disease resistance, such as resistant vegetable varieties.

If you have a plant or plants that constantly seem to have something attacking them despite your best efforts, consider removing them and replacing them with plants you have found to require less care.

In vegetable gardens and flower beds where plantings are removed and new plantings are put in, crop rotation is important. Planting the same type of plant in the same soil year after year can cause a soil buildup of insect and disease organisms that attack that particular plant. Always try to plant different things in different places in your flower or vegetable garden every year whenever possible.

Proper sanitation is another important factor in controlling insect and disease problems. Overgrown areas near gardens and landscaped areas can serve as alternate hosts and places of refuge and breeding for pests. Always keep your yard, gardens and adjacent areas as weed-free as possible.

Fruit and fallen leaves infected with disease should be raked up, bagged and thrown away. If left on the ground, these old leaves and fruits can harbor diseases and serve as a continuing source of infection on the plant. Never leave rotten vegetables and leaves on the ground in your vegetable garden.

Many disease organisms live in the soil and are splashed onto plants by rain. Applying mulch on soil under plants can reduce incidence of these types of diseases. This is especially helpful when growing fruit and vegetable crops like tomatoes, squash and strawberries.

Mulches are critically important in saving work and reducing the use of herbicides in controlling weeds. We constantly fight weeds, and if you don’t have all of your beds mulched about 2 inches deep, you are missing out on our best defense against these pests.

Diagnosing plant problems

Despite your best efforts to avoid them, pest problems will likely have to be dealt with at times. Plant pathogens such as fungi, bacteria and nematodes cause diseases. Insects and mites feed on ornamental trees, shrubs, flowers and vegetables. Weeds compete with desirable plants for space, sunlight and nutrients. Even adverse environmental conditions can contribute to plant health problems.

When problems do occur, accurate and rapid diagnosis is critical for selecting the best management practices. Before you attempt to correct a problem, you must first properly determine its cause. Misdiagnosing the cause of plant problems may add to the losses and lead to wasted effort and money spent needlessly. It does no good if you use the wrong pesticide or use a pesticide when it wasn’t needed. Unfortunately, diagnosing the cause of problems is not always easy for the average gardener.

That’s where the LSU AgCenter can help. Every parish has an LSU AgCenter Extension office. Agents in those offices can help you identify weeds, insects or disease problems and recommend solutions. Agents are familiar with many of the plant problems people commonly encounter. They can help evaluate the situation, provide a proper diagnosis and recommend appropriate action.

If further analysis or help with identification is needed, the agent may recommend collecting and submitting the appropriate samples to the LSU AgCenter Plant Diagnostic Center.

Services available through the Plant Diagnostic Center include plant disease diagnosis (those caused by living organisms – such as fungi – and those caused by environmental stresses), insect and mite diagnosis and identification related to plants only, nematode diagnosis and identification, and weed identification.

Raj Singh, the “Plant Doctor” at the Plant Diagnostic Center, has the training and experience to help solve the problems you may have with unhealthy plants. For more information, email Dr. Singh at or call 225-578-4562.

You may also want to visit the Plant Diagnostic Center website at There you will find information on fees for services, how to properly submit samples, forms for submitting samples and lots of other helpful information.

Rick Bogren

Last Updated: 6/27/2014 12:53:29 PM

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