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Greenhouse Whitefly

Greenhouse Whitefly

Trialeurodes vaporariarum

insect

In a Nutshell

    Small white flies and eggs on underside of leavesHoneydewSooty moldAffects plants in greenhouses

Hosts: %1$s

· Capsicum & Chili · Cucumber · Pumpkin · Zucchini · Tomato · Peanut

Symptoms

Greenhouse Whitefly is a pest that appears on a variety of crops grown in greenhouses. Both adults and nymphs are sap-sucking and excrete a sticky substance (called honeydew) onto leaves, stems and fruits. They thrive in warm conditions, which is why usually it is not a problem on outdoor plants. On infested plants, small white flies are scattered when the plant is shaken. The eggs are laid on the underside of the leaves. The nymphs are flat, oval and pale green in color. The honeydew leads to the growth of black sooty mould forms.

Trigger

The glasshouse whitefly lay 2 to 7 eggs on the underside of the leaves every day. The quantity of eggs and the development of larvae and flies is temperature-dependent. Flies thrive during warm dry seasons. The larvae suck the sap after hatching and pupate afterwards. Adult whiteflies cannot live without feeding on a host plant for more than a few days. This makes weed-management an important population control measure.

Biological Control

At warm temperatures the parasitoid wasps Encarsia formosa and Eretmocerus eremicus are effective against the pest. The treatment is not effective anymore at cooler weather conditions. Predatory beetles like Delphastus sp. or lacewing larvae also work. In high humidity conditions the fungal pathogens Verticillium lecanii and Paecilomyces fumosoroseus can be useful control agents. Frequent sprays with plant extracts (neem oil) or insecticidal soaps may help control established infestations.

Chemical Control

Always consider an integrated approach with preventive measures along with available biological treatments. Frequent sprays with contact insecticides deltamethrin, lambda-cyhalothrin, cypermethrin, pyrethrins or products which contain a blend of surfactants and nutrients may control established infestations.

Preventive Measures

    Watch for signs of whitefly on new purchases or transplantsUV-absorbing greenhouse plastic films can reduce infestationsAt early stages of infection, use yellow sticky traps to reduce populationsAvoid warm and dry conditionsControl weeds inside and around the greenhouseRemove alternate host plantsShort fallow at warm temperatures can be enough to rid the greenhouse of potential whitefly coloniesEnsure balanced fertilizationRemove plant residues from the greenhouse after harvest