If you have noticed that greenhouse plants have holes in leaves, it indicates on damage from people or insects. Human can damage the leaves when brushing against an opening leaf bud which leads to torn edges. When a plant is suffering from diseases, the leaves are covered with spots or change color rather than have holes in them.
So, why greenhouse plants have holes in leaves?
Insects like slugs and snails cause irregular holes in the leaves of many plants. You can identify them by slime tracks. Chewing insects like caterpillars have a pair of mandibles that lets them to cut, tear, crush and chew food items.
A sing of caterpillars eating the greenhouse crops are holes in the leaves which are spun together. Caterpillars mainly attack vegetables and ornamental plants. It can also target tomato fruits leaving tunnels in the fruits during the night. However, with these easy tricks you can get rid of tomato bugs easily.
A common garden insect – Earwig – feeds and causes irregularly shaped holes on the leaves and lower flower petals of Carnations, Chrysanthemums in a greenhouse. Earwigs have dark brown bodies and pincer-like tails.
What are the major insect pests in greenhouse?
Aphids
Small, sap-sucking insects. Can be green, black, grey or orange colors. They attack a wide range of ornamental plants, fruit and vegetables. The plant becomes unsightly and grows slowly. Aphids can carry viruses which cause plant diseases.
Caterpillars
These are the larvae of butterflies and moths. They have chewing mouthparts consisting of jaw-like structures (mandibles) with teeth. So they can tear off and chew plant tissue. Moreover, caterpillars tunnel within stems and between leaves.
Earwigs
These are common garden insects with dark brown bodies and pincer-like tails. They usually hide in a greenhouse and come out at night to feed on the leaves and lower flower petals.
Nematodes (Roundworms)
Microscopic worms that live in soil. They attack Tomatoes and Chrysanthemums. The roots of the Tomato plant have corky swellings and Chrysanthemum leaves develop brown patches.
Leaf Miner
It is a larval stage of a variety of insects. The adult female insect lays eggs on the underside of the leaf. Then larvae burrow into the leaf and eat the tissue creating the tunnel-like appearance on the leaves.
Mealybug
It is a small insect with white, cottony fluff. They can cause large clusters on the stems and under the leaves. Mealybugs can attack a variety of plants and infestation can lead to wilting of the plant.
Red Spider Mite
The most common greenhouse pest. It is a sap-sucking insect and it attacks the underside of the leaves of a variety of plants especially in hot and dry conditions. The sign of spider mite infestation are yellow spots on the leaves and fine webbing.
Scale
These insects look like small brown discs. Scales attach to the underside of the leaves and along the stems. They pierce plant tissues with the mouthparts and suck the sap. The body is covered with outer waxy shells.
Slugs
It is a shell-less mollusc. They can eat vegetables and fruits causing damage to crops. However , they prefer to feed on tender leaves leaving irregular holes in them. They leave slime tracks wherever they go so you can identify them easily.
Thrips
These are tiny black pests that fly or jump from leaf to leaf and damage flowers. They have asymmetrical mouthparts and suck the juices out of the plant. The common sign of thrips infestation are spots on the leaves. Thrips attack Begonias, Crotons, Fuchsias and other ornamental plants.
Vine Weevil
An adult vine weevil is a beetle that damages leaves and grubs (larval stage) attack plant roots. These grubs cause a real damage because they live in compost and eat roots, bulbs and tubers.
Whitefly
It is a very common pest which can lead to serious damage to your greenhouse plants. You can recognize infestation with whiteflies by yellow plant leaves and the whole plant can wilt too. Some whitefly species produce honeydew which leaves shiny residues on the leaves.
Apart from leaving holes in the leaves, insects can into the fruits of the plants that you grow in a greenhouse. To find out what is eating tomatoes, you can read this post. Loosing fruits because of outdoor animals is devastating, that is why it is better to grow tomatoes in a greenhouse.
