Concern has been building over the use of chemical pesticides in and around the garden, even those relatively safe materials available over the counter.
Guidelines for using commercial pesticides are being tightened to the point where many feel it is impossible to follow them all and still operate. Yet, we have become so used to blemish-free plants that cooperative extension associations and plant information services often receive near-frantic calls from homeowners whose plants have sustained a mere nibble from a passing caterpillar.
Pesticides, as we know them today, were not generally available until after World War II. Before that, pesticides were largely from such natural materials as rotenone from the root of a tropical plant, pyrethrins from the painted daisy and nicotine sulfate from tobacco. Most of them acted as repellents or as systemic poisons that killed on contact.
While those methods had some success, the new generation of chemicals was much more effective and soon dominated the field. Their potential danger to the environment and to humans was unrealized. It was eventually learned that those pests and disease organisms that managed to survive developed a resistance, making it necessary to develop even more potent chemicals. Eventually, the more dangerous ones were restricted or banned. In earlier times, the public accepted fruit and vegetables with blemishes. The new generation of chemicals, despite their problems, conditioned home gardeners and consumers to expect near perfection, and now most gardeners and consumers find it difficult to accept less. It is almost impossible to attain that degree of control using other methods.
The most promising approach to pest control in Melbourne is through I.P.M., Integrated Pest Management. Rather than spraying or dusting to prevent problems, this system relies on close monitoring to determine when a pest or disease poses a sufficient problem to merit control. One must be able to identify the problem and the signs that indicate the presence and identity of pests.
Plant species and cultivars that are resistant to pests and diseases are also important. Such plants require little, if any, control measures, and listings are available from local cooperative extension offices, nursery catalogues, horticultural publications and botanical gardens and nurseries.
Certain other practices can also be effective. Early planting will result in radishes that mature before they can be infested by root maggot, and raising the cutting height of the lawn mower will help prevent diseases like dollar spot. Watering roses early in the day so that wet foliage will dry before evening will help prevent black spot.
Biological factors can also play an important role in pest control; however, one must realize that the results will not be as rapid as those obtained with chemicals. Milky-spore disease attacks the larvae of Japanese beetles and reduces their number. Bacillus thuringiensis, a bacterial disease, will control larvae of most kinds, although not until they have done some damage. It offers no danger to mammals. Lady bird beetles (lady bugs) eat large quantities of aphids, while tiny wasps of various kinds attack such insects as whitefly and gypsy moth.
These beneficial insects do not stay put and may decide that they like a neighbor’s pests more. Also, they may be just as susceptible to chemical sprays, than the pests one seeks to control.
When absolutely necessary, chemicals may be used, but there are options. The chemical products we are trying to avoid may bring about the most rapid control. But, when used sparingly as a part of an Integrated Pest Management program, the amount placed in the environment is greatly reduced. This method reduces the chance of pests building resistance, and reasonable control can sometimes be attained with concentrations of chemicals reduced up to 50 percent.
One may choose to go back to old methods using rotenone or pyrethrins. That is the choice of organic gardeners and farmers. But sometimes those organic materials are actually more toxic and remain in the environment longer than their synthetic counterparts, a factor that organic practitioners ignore.
Also available are insecticidal soaps, both dormant and summer oil sprays and various concoctions of natural ingredients like garlic and Tabasco sauce. Some have proven effectiveness, while others seem to work for some and not for others.
While there are alternatives to chemical control, including I.P.M. or any of its components, their effectiveness must be weighed against environmental concerns. If the choice is against chemical controls, then a certain amount of damage must be expected, but that can be acceptable if one believes strongly in the cause it supports.
