Pest repellents can aid the home gardener (Released: 8/13/96)
by Renu Sehgal, Office of University Communications.
STORRS, Conn. -- Is something eating your basil? Are there notches on your rhododendron?
If your plants are being eaten by pests, there is hope you can save them without using the traditional pesticides. ''The first step is to determine what the problem is -- insect or disease,'' said Leanne Pundt, a Cooperative Extension System educator.
Home gardeners should contact their local Cooperative Extension office for advice specific to their situation, but Pundt offers some general tips for pest infestations.
If the problem is a few pests, pick them off and throw them in a bucket of soapy water. Commercial traps are also available.
''Sometimes, the homeowner may notice damage when the pest has already gone. And sometimes, there are no solutions to the problem and you have to remove the plant,'' she said. ''Know what pest it is, what stage of development it is most vulnerable and where it lives. For general pest infestations there are some newer materials such as horticulture oils and soaps that are lower in toxicity than traditional pesticides.''
Oils and soaps work on contact with the targeted pest. So when treating for mites, you must ensure the spray reaches the undersides of the leaf, Pundt said. The products are also biodegradable -- after the spray has dried, beneficial insects can safely re-enter the treated area.
Horticulture oils were used in the past during the dormant season, but now have been refined for use during the growing season. The oil, which suffocates insects, is effective against soft-bodied pests, including aphids, whiteflies and mealybugs. Now it also is labelled for powdery mildew on squash, melons, beebalm, phlox and zinnia, Pundt said. Read the label carefully because some plants are sensitive to the oil, she said.
''Horticulture oil will remove the blue bloom of Blue Spruce and turn it to green,'' Pundt said. ''And while the oil is generally not toxic to mammals, it is toxic to fish so home gardeners should not use the oil near ponds.''
Insecticidal soaps can be used up to the day of harvest. Some gardeners have concocted their own soaps, but Pundt said they should rely on the commercially marketed products. These homemade recipes include dishwashing liquids, which could remove wax from plant leaves, she said.
Always read the labels of any product purchased. Avoid using soaps and oils during times of high humidity, high temperatures or when plants are under stress, she said. Spray in the morning so the soap does not dry quickly.
''Then spot treat plants and check to see if the pest population is increasing or decreasing to evaluate the treatment,'' Pundt said.