![]() ![]() Sevin (carbaryl) is not effective against many aphids so it is generally not a good choice for control unless recommended specifically. Be sure that the plant or crop that you are treating is listed on the product label. As with oils and soaps, coverage is very important and a follow-up application may be necessary. Nervous system insecticides, such as malathion, Dursban (chlorpyrifos), and Orthene (acephate), are labeled for use on many shade trees and ornamental plants for aphid control. They require direct contact with the insects and leave no residual effect. As with summer oils, they apparently work to disrupt insect cell membranes. There is no residual effect so additional applications may be necessary.įatty acid salts or insecticidal soaps are very good against aphids. Do not spray dormant oils during the growing season. Weather conditions, especially high temperatures, can increase the potential for foliage burn. Check the label for cautions on sensitive plants oils can injure the foliage of some plants. ![]() They kill by suffocating the insects and/or disrupting their membranes. Summer oils can be used against aphids on some types of trees and ornamental plantings. Aphid control is rarely feasible in these situations. Commercial applicators may have the necessary equipment but these treatments may be very expensive. Skips in coverage are common and there is a significant potential for applicator exposure through drift and runoff. Hose-end sprayers can be used on 15 foot to 20 foot trees but they need to produce a stream rather than an even pattern to reach these levels. It is difficult to treat large trees because of the high spray pressure necessary to penetrate the foliage and to reach the tallest portions of the tree. Thorough coverage, directed at growing points and protected areas, is important. Since aphids tend to remain on the lower leaf surface, they are protected by plant foliage. ![]() This means that the aphids must be hit directly with spray droplets so that they can be absorbed into the insect's body. Most products used for aphid control work as contact insecticides. In some cases, this may provide adequate control. If aphid colonies can be found on about 5% or more of foliage tips of a plant or planting, then a control measure should be considered. Small numbers of individual colonies on small plants can be crushed by hand or removed by pruning as they are found. The presence of these colonies indicates that the aphids are established on the plants and their numbers will begin to increase rapidly. Examine the bud area and undersides of the new leaves for clusters or colonies of small aphids. The flight of winged colonizers cannot be predicted, so weekly examination of plants will help to determine the need for control. CONTROLĮarly detection is the key to reducing aphid infestations. These winged forms fly off in search of new hosts and the process is repeated. Aphid numbers can build until conditions are so crowded, or the plant is so stressed, that winged forms are produced. Less than a dozen aphid "colonizers" can produce hundreds to thousands of aphids on a plant in a few weeks. ![]() The process is repeated several times, resulting in a tremendous population explosions. Usually, all of them are females and each is capable of producing 40 to 60 offspring. They mature in 7 to 10 days and then are ready to produce live young. The immature aphids or nymphs that are left behind feed on plant sap and increase gradually in size. They deposit several wingless young on the most tender tissue before moving on to find a new plant. Infestations generally result from small numbers of winged aphids that fly to the plant and find it to be a suitable host. Resistant varieties or sequential plantings may be helpful in reducing problems with some viruses that attack annual plants. Aphids carrying viruses on their mouthparts may have to probe for only a few seconds or minutes before the plant is infected. However, it is seldom possible to control these diseases by attempting to kill the aphid vectors with an insecticide. Some aphids are very important vectors of plant viruses. The drops can attract other insects such as ants, that will feed on the sticky deposits. The appearance of sooty mold on plants may be the first time that an aphid infestation is noticed. A fungus called sooty mold can grow on honeydew deposits that accumulate on leaves and branches, turning them black. The honeydew that drops from these insects can spot the windows and finish of cars parked under infested trees. Aphids produce large amounts of a sugary liquid waste called "honeydew". ![]()
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