There are two places commercial farmers plant tomatoes. One place is outside in the fields and the other in greenhouses.
Tomatoes planted in the fields.
Tomatoes are liable to attack from a large number of insects. From the time plants first sprout in their seed beds until the fruit is harvested Aphids, flea beetles, leafminers, and spider mites threaten young plants.These bugs cause minimal damage to the foliage.but severe damage may result either from their feeding on the fruit or by spreading certain diseases.
Tomatoes grown in greenhouses have many of the same pests as field tomatoes do.
Aphids, whiteflies, leafminers, and spider mites are likely to infest greenhouse crops while beetles, grubs, or caterpillars.are likely to be more scarce indoors. Sometimes moths enter and lay their eggs in the greenhouse. Other pests such as armyworms, fruitworms, and loopers may enter a greenhouses on plants being introduced.
Below I am going to list some of the pests that attack tomato plants.
Pests that feed on the upper plant
The Tomato pinworm when young is yellowish-gray. The larva are only a few millimeters long, and make make blotches on the leaves. The older larva are yellow, green, or gray or purple-spotted and grow up to 8 mm long. They fold the leaves and web them together. They also bore into the stems, buds, and fruit and make pinholes and discolored blotches on the plant.
Blotches are caused when the larva turns itself around in the leaf during its feeding.
Tomato fruitworms are a cream colored or yellowish-green worm with few markings; After moulting its colour changes to green, reddish, or brown with pale stripes and scattered black spots.
This worm is moderately hairy and grows up to 44 mm in length.. It has 3 pairs of legs, 5 pairs of prolegs and chews holes in fruits and buds of the tomato plant.
The vegetable leafminer is a colourless to bright yellow maggot which grows up to 3 mm long.
It has a pointed head and makes burrows known as serpentine mines into the plants leaves. Each mine is slightly enlarged at one end
The Tobacco budworm is a caterpillar that is similar to the tomato fruitworm. When mature these worms are smaller and thinner than tomato fruitworms. On the skin of tobacco budworms are microscopic spines which are more slender, longer, and occur closer to the hairs than those on the tomato fruitworm.
Pests that chew and make holes in leaves
There are several species of Blister beetles which are slender and elongated growing up to 19 mm long. They have prominent heads and their bodies have different colourings. They are usually black. black with yellow margins, or black and yellow striped They leave; stringy black excrement on plants. Foliage becomes ragged and sometimes plant growth becomes stunted.
Cabbage looper is a green caterpillar with longitudinal white stripesand a bodywhich grows up to 30 mm long tapering towards its head. It has 3 pairs of legs near its head and 3 pairs of fleshy prolegs. The young larva live on underside of the leaves and consume tender leaf tissue leaving the leaf veins intact.
The Colorado potato beetle is yellowish-brown, oval and convex and grows up to 14 mm in length. It has 5 black longitudinal stripes on each wing cover and several black spots on the area behind its head. It; feeds on the leaves and the terminal growth of the tomato plant.
There are various species of tiny, darkly colored flea beetles They vary between 2.5 to 4.5 mm in length and have a solid colored body or ablack body with pale yellow stripe on each wingcover.
They make tiny round holes in foliage of the plant.
Hornworms are caterpillars coloured green to reddish-brown which grow up to 90 mm long with a red or black anal horn. The body has 7 diagonal or 8 V-shaped marks on each side with round black spiracles along each side of body. This caterpillar strips leaves from the vines and sometimes feeds on the tomato leaving a large open scars on the fruit.
Here is a list of pests that suck the sap out of the plant or the fruit causing leaf discoloration, deformed leaves or fruit, or even defoliation of the plant.
Aphids are soft-bodied, pear-shaped insects which have a pair of dark cornicles and a cauda protruding from the abdomen; Some are winged and some are wingless. The wingless aphid is the most common of the aphids. The aphids feed in colonies causing discoloration or mottling of the foliage. They excrete a honeydew which encourages a sooty mold to grow.
The green peach aphid is a pale yellow to green wingless bug. The adults grow up to 2.4 mm in length. The winged adults have dark dorsal blotches on yellowish-green bodies. Nymphs have 3 dark lines on their abdomens.
Potato aphids, both adult and nymph are coloured pink, green and pink mottled or light green with dark stripe. Adults grow up to 3.5 mm long and have long slender cornicles about twice as long as the cauda .
The Greenhouse whitefly is a white moth-like insect measuring about 1.5 mm in length. Infestations contain tiny yellow crawlers and/or green, oval, flattened, immobile nymphs and pupae. They cause leaves to turn yellow and drop from plant; sometimes cause plants to become stunted and unreproductive. A black sooty mold is often found on leaves when the whitfly is present.
A Stink bug is a green or brown shield-shaped insect which grows up to 19 mm in length.The nymphsare green with orange and black markings. These insects pierce the buds causing them to fall from the tree while the nymphs attack the fruit causing it to be deformed.
The Silverleaf whitefly adult is smaller than the others with males reaching 0.82 mm in length and females 0.96 mm. They are s yellow in color and hold their wings at a 45-degree angle that looks rooflike.
The nymphs are a glassy to opaque yellowish colour and have a flattened scale-like body with the margin near the leaf surface; The pupa are flattened, dome-shaped and lack setae. Plant growth is stunted and the plant does not produce fruit. As with whitefly's there is always a black sooty mold present .
The Western flower thrips adult grows to about 1 mm in length. Its colour varies from a pale yellow to dark brown and it has a rounded, narrow abdomen. The larvae are yellow. Plants infected with thrips are distorted and have a silvery appearance and wilt.
Pests that feed on roots or lower stems
The Cutworm is a fat, gray, brown, or black caterpillar measuring 40 to 50 mm in length when fully grown It has 3 pairs of legs near ts head and 5 pairs of fleshy prolegs This worm is active at night. The young caterpillar climbs up on leaves to feed while the older caterpillar attacks and severs seedling stems near the ground. These worms hide in soil burrows at the bases of plants during the day .
The Southern potato wireworm is a slender, wire-like cylindrical larva with 3 pairs of short legs near its head and a pair of fleshy anal prolegs. It has a white, cream, or yellow-gray body with red-orange head capsule and is ; about 17 mm long when fully grown. It has a closed notch in itslast abdominal segment. It makes ragged irregular holes in roots of the plants.
After reading through the pests that can attack a tomato plant who would want to be a tomato farmer.
The question is how do we home gardeners protect our tomaties from these pests.
There are of course a number of poisonous sprays available on the market which kill most of the pests listed above but unfortunately also kill the good insects which eat and kill the pests.
If your tomato garden contains a small number of plants then it is easy to look for cutworms curled near the base of young plants. You may have to dig a few inches into the soil to find and remove them. An easy way to protect young plants is to place a paper collar around new transplants. Push the paper collar into the soil at least 2 inches. The collar will decompose in time as the plant grows.
A second method is to encourage birds to visit your garden by placing birdbaths and feeders near the planting beds.
When preparing your tomato beds apply beneficial nematodes ( Nematodes are usually vermiform, long and slender, but some species are swollen. Most people know them as roundworms because their cross-section is round. ) when the cutworms first appear in the spring. They attack the cutworms by laying eggs inside the caterpillar and when the eggs hatch the ravenous hatchlings consume the cutworm before it can pupate into an adult moth.
As a last resort place bran mixed with Bacillus thuringiensis, an organic control for caterpillars, over the surface of new planting beds one week prior to planting. Bacillus thuringiensis (or Bt) is a bacteria and is safe to use around children and pets. Cutworms already present in the soil will eat the Bt-laced bran instead of your new seedlings.
For all the other bugs in your garden consider a natural pest control product such as a herbal pesticide-fungicide. A product called Zero Tolerance is available in the USA and appears to control most of the abovementioned pests. Here in South Africa enquire at the local nurseries for something similar.
In days gone by farmers used to mix up their crops in such a way that one crop protected the other by chasing away pests .
Here are a few companion plants that may be planted with your tomatoes.
Basil used to repel insects.
Tansy Plant on the borders of your veggie patch as they tend to grow wild and become invasive.
Tansy is an insect repellant which repels moths and ants. Also good for fruit fly.
Nasturtium controls aphids and also acts as an insect repellant either fresh or dried. Also good for deterring ants
Marigolds deter nematodes, also an Insect repellant . If you have cutworms plagueing your tomatoes it might not be a good idea to plant marigolds too close as they tend to chase away the good and bad nematodes.
Planting tomatoes where marigolds have been grown as a green manure, and dug into the soil to decompose, will also control parasitic nematodes.
Other plants that make good companions for tomatoes are:
Rocket which acts as a tonic to tomatoes.
Basil and mint improve the health and flavour of tomatoes and also repel the white cabbage moth.
Pyrethrum is a good insect repellent and will keep slugs at bay.
Tomatoes love growing in their own aroma so place any pieces of plant that have been pruned onto the ground around them.
Tomatoes like growing with, dill, parsley, carrots, celeriac, bush beans, carrots, cabbage, kohlrabi,
lettuce, leeks and spinach.
If you have asparagus growing in your garden plant your tomatoes in rows between the asparagus plants.
The asparagines in asparagus plants will protect the tomatoes from insects, whilst the solanine in tomatoes will help the asparagus plants by repelling nematodes.
Tomatoes do not grow well near beetroot, fennel or peas.
If anyone has any further information on how to protect one crop by planting another in close vicinity please let Geoff Fairman know so that I may include the information on this page for the benefit of all.
I trust that you might now be able to at least identify the bug that is destroying your tomato patch.