Horticultural Diseases and Pests - Alphabetically
Horticultural Diseases and Pests - by Host
Aphids are soft-bodied insects with relatively long legs and antennae. There are winged and wingless forms varying from yellow-green to red to brown depending on the type and time of year observed. Regardless of the species, they are all normally 1/8 inch or less in length. All have a pair of cornicles (tail-pipe appearing structures) on the rear of their bodies which can be seen easily with a hand Iens. They have piercing-sucking mouthparts and feed by sucking sap from plant tissue. Aphids can increase rapidly in an extremely short time. During warm weather some species can complete a generation in less that two weeks.
Aphids feed on a wide range of greenhouse crops. A number of species exist, but one of the most common is the green peach aphid. They feed particularly on buds and the undersides of leaves by inserting their tube-like piercing mouthparts and withdrawing sap. Leaves from affected buds may be a distorted and often display chlorotic (yellow-white) speckles where cell contents have been sucked out. A secondary problem arises from sugary honeydew excreted by the aphids. Leaves may appear shiny and sticky from this material which supports the growth of black sooty mold (a common greenhouse fungus). Aphid seldom kill plants. Also, aphids are able to transmit viral diseases.
Aphids are often controlled by natural forces, such as driving rains, or high or low temperatures. Insect predators include lady beetle adults and larvae, lacewing larvae, and syrphid fly larvae.