Greenhouses are places of peace and serenity. However, they are also a battlefield where thousands, maybe even millions of combatants perish. Unfortunately for us and our plants, we can still lose the war after slaying legions of pests.
Aphids. Aphids can multiply at a mind boggling rate. They reproduce asexually, so every single one of them is a potential mother. Adult aphids can produce six to ten offspring each day for 20 to 30 days! It’s easy to see how this can create a massive army of aphids in a short time.
Controlling aphids requires a regimen of insecticide treatments, just one spraying won’t usually take care of the problem.
Whiteflies love fuchsias, poinsettias, lettuce, tomatoes and cucumbers. The immature whiteflies are unaffected by insecticides used on adults, so the treatment must be administered several times at specific intervals.
Fungus Gnats, Shore Flies, Bloodworms. These pests love high humidity and moist soil, so greenhouses are their paradise. Fungus gnat larvae are a frustrating problem, attacking the roots, crown or stem of plants, often for quite some time before the infestation can be noticed. Shore flies are similar, but don’t damage plants directly – they spread soil pathogens around the greenhouse. Bloodworms are larvae which accumulate in standing water.
Avoid excess watering and clean up standing water or wet areas in the greenhouse to combat these annoying pests.
Cutworms, Armyworms, Loopers, and other Caterpillars. These guys love chewing on leaves, stems and fruits of almost any plant. Get rid of these pests by using a spray with bacillus thuringiensis – a soil dwelling bacterium.
Thrips. Tiny slender bugs of about one twenty-fifth of an inch long, thrips feed directly on the plant surfaces, and lay eggs in the leaves. Screens help keep them from flying in, but they may also catch a ride on newly arriving plants.
Leafminers are small fly larvae which feed between the surfaces of leaves. Since they grow inside the leaf, insecticides are ineffective. Good practices and removal by hand, and getting rid of the infected leaves are how to defeat them.
Mites are one of the most difficult pests to eradicate, as they’re resistant to pesticides. One way to combat them is with predators. Predators need to be specially chosen for specific infestations.
Slugs and Snails are night feeders, hiding in the daylight hours. It’s easy to spot an infestation as you can see their slimy trails everywhere. Keeping your greenhouse clean and sanitary is important to combating slugs. There are a variety of ways to keep them out. One of the cleverest methods is installing salt-embedded plastic strips around your plant benches.
With most pests, the best way to defeat them is to prevent them from infesting your greenhouse in the first place. Ensure your greenhouse is pest free before planting, inspect new plants before introducing them, and only buy plants from a place you trust. Keeping the greenhouse clean and tidy, and putting screens over the vents will also help a great deal.