Gardening: Consider a more natural alternative to harmful pesticide use

The harmful effects of pesticides and other toxins on our environment are increasingly in the news. Because our climate is tropical, we have more pests and diseases than most areas and use more pesticides, fungicides and fertilizers.

A new and better system to insect and disease management replaces the practice of spraying everything in the yard on a set schedule. It is called Integrated Pest Management. The idea is to use many methods to manage pests and ultimately use less pesticides.

These methods include:

• Mechanical method — Pick caterpillars off the shrubs and step on them. Prune diseased wood and pull weeds from the garden.

• Physical methods — Use heat, cold, light, etc., to kill pathogens (heating soil) or to prevent food organisms from growing (cold soil).

• Biological method — Learn what insects are beneficial such as ladybugs, earwigs, etc. Attract birds by planting diverse and native species to create an ecosystem.

• Cultural method — Control through practices such as fertilization, irrigation, mulching, soil preparation and sanitation (removing diseased wood or leaves from the site). Avoid extremes of fertilizer and water — too much or too little can weaken plants and invite pest problems.

• Host plant resistant method — Plant varieties developed to be resistant to damage by certain pests. An example is the Floratam variety of St. Augustine grass. It is more resistant to chinch bugs than other varieties. Plant shrubs and trees where conditions will be favorable for their growth.

• Regulatory method — Laws were established to control the movement of plants and animals infested with certain pests and diseases from place to place. An example is the quarantining of areas with citrus canker.

• Chemical method — Use pesticides, repellants and attractants. Try to use pesticides which are not as harmful to beneficial insects like BT, horticultural oils and insecticidal soaps. Tolerate a few pests and a little damage. The pests are a source of food for beneficial insects that you want to keep around.

When using a management system, proper iden tification of insects is a must.

There are many books available with pictures and information on insects in Florida. A very good one is titled Florida Insects and costs under $5.

The Collier County Extension Office in Immokalee has excellent literature on local insects as well.

Learn your yard and scout it regularly. Learn about beneficial insects which will feed on the harmful pests and learn to recognize when they are doing their job.

If aphids, scale or whitefly nymphs have a small pinhole, they have been parasitized by a tiny parasitic wasp. If you detect predators, every effort should be made to preserve them. Allow the beneficial insects to control the pest population before applying insecticides.

Most plants in the landscape are over sprayed resulting in unnecessary environmental contamination and often upsetting the natural predator versus pest balance. Spray only when a pest population is present and damage is beginning to occur.

Pests of ornamentals are grouped according to the way they damage plants.

• Insects with piercing/ sucking mouth parts — They have beak-like mouth parts used for piercing the plant tissue and sucking plant juices. Examples are scales, aphids, whiteflies, mealybugs, thrips and lacebugs.

• Foliage feeding insects — They feed on the leaves, flowers or roots. Examples are caterpillars, beetles and grasshoppers.

• Spider mites — These pests are not insects but closely related to spiders and scorpions. They suck plant juices with piercing sucking mouth parts.

• Leafminer — These are small larvae of flies, beetles or moths that tunnel between leaf surfaces.

• Borers — These are either the larvae of moths or beetles that bore into twigs and trunks of plants.

If a population of pests gets out of control, use a garden hose and direct a strong spray of water at the stems and undersides of leaves to lower the pest population.

If you do have to spray, try to use the less toxic products, such as insecticidal soap.

Neem insecticide, a derivative of the neem tree, acts as a reproductive and feeding inhibitor, disrupter and growth regulator. Pyrethrins from crysanthemums will paralyze and kill insects. Another product uses potassium salts of fatty acids that penetrate the outer shell of soft-bodied pests, causing dehydration and death within hours. Oils smother insects. And bacillus thuringiensis, Dipel or Thuricide, a natural bacterium for control of moth or butterfly larvae is also effective.

Insecticides may be required to control pests when they reach damaging levels on plants. Before using a chemical insecticide you should consider the following points.

1. Select the right material. Only use an insecticide that is recommended to control the target pest and is safe on the host plant.

2. Use the right amount. Too little won't control the pest and too much may injure the plant. Read the label for the correct dosage rate.

3. Apply it the right way. Thorough coverage of leaves, especially the underside, twigs and branches is essential. The insecticide must reach the area where the pest is feeding.

Using a spreader sticker will aid in pesticide adhering to the leaves for better coverage and control.

Systemic insecticides are absorbed by the host plant and translocated throughout the tissues which makes the plant toxic to certain mite and insect pests for up to six weeks.

They can be taken up by the roots when applied in granular form or absorbed by foliage or stems using sprays or injections. Systemic insecticides are effective in controlling sucking pests and mites. They do not give satisfactory control for chewing insects. Examples of systemic insecticides are Cygon, Orthene and Di-Syston Granules.

Malathion is effective in controlling sucking insects. Sevin controls a wide range of chewing insects. Kelthane controls mites. Lindane, now no longer available, was for borers and leafminers. You will have to search for a new product for these insects. Read labels to identify which sprays are safe on your plants.

Phytotoxicity, or plant injury, can be caused by certain pesticides on ceratin plants. The degree of injury can be affected by conditions like temperature, humidity and other environmental factors. It is best to apply pesticides during the cooler part of the day. Plants are less likely to be injured when protected by partial shade as opposed to being in direct sun. Some materials can injure plants that are stressed for moisture. Plants should be well watered a day or two in advance of being treated with insecticides. Above all else remember to read the label.

If you use a professional spray company, you should ask about an Integrated Pest Management program, including scouting services and applying pesticides only when needed.

Often you will be paying for knowledge, not chemicals.

Don't allow routine blanket sprays in your yard. And be prepared to pay for professionals' time, even if they don't spray any chemicals during the visit.

The benefits of a mangement system include less exposure to pesticides for gardeners and homeowners; reduced exposure to fish and wildlife; and reduced pollution of water, air and soil. Finally, we would all benefit from a cleaner environment.

Eileen Ward and her husband, Peter, own and operate Greensward of Marco Inc., a lawn maintenance and landscaping company. Besides completing horticultural courses from the University of Florida, she has a commercial maintenance spray license and is a registered dealer in agricultural products in Florida. To reach Ward, call 394-1413.