PESTS OF TOMATO

Tomatoes are subject to attack by a large number of insect pests from the time plants first emerge in the seed bed until harvest. Aphids, flea beetles, leafminers, and spider mites threaten young plant-bed tomatoes. In the field, flea beetles, aphids, leafminers, stink bugs, and fruitworms cause minimal damage to the foliage. However, severe damage may result either from their feeding on the fruit or by spreading certain diseases.

Greenhouse tomatoes have many of the same pests as field tomatoes. Tiny pests such as aphids, whiteflies, leafminers, and spider mites are more likely to infest greenhouse crops than beetles, grubs, or caterpillars. Occasionally moths enter through holes in screens or fans and lay eggs in the greenhouse. Even in screened greenhouses, armyworms, fruitworms, and loopers may be brought into the greenhouses on plants.

KEY TO TOMATO PESTS

A. Pests that feed on the upper plant

  1. Pests that mine leaves or bore into fruits and/or buds

    1. Tomato fruitworm - Early instars: cream colored or yellowish-green with few markings; later instars: green, reddish, or brown with pale stripes and scattered black spots; moderately hairy; up to 44 mm long; 3 pairs of legs, 5 pairs of prolegs (Fig. 228A); holes are chewed in fruits and buds

    2. Tobacco budworm - This caterpillar is similar to the tomato fruitworm except mature worms are somewhat smaller and slightly more slender than tomato fruitworms (Fig. 228B); in addition, the microscopic spines on the skin of tobacco budworms are more slender, longer, and occur closer to the setae (hairs)

    3. Tomato pinworm - Young yellowish-gray larva only a few millimeters long, making blotch mines in leaves; older yellow, green, or gray, purple-spotted larva up to 8 mm long (Fig. 229), folding leaves and webbing them together, or boring into stems, buds, and fruit; fruits with pinholes and discolored blotches

    4. Vegetable leafminer - Colorless to bright yellow maggot, up to 3 mm long, with pointed head; makes serpentine mines in leaves; each mine slightly enlarged at one end (Fig. 230)

  2. Chewing pests that make holes in leaves

    1. Blister beetles - Several species of slender, elongate beetles up to 19 mm long; have prominent heads; bodies variously colored but usually black (Fig. 231A), black with yellow margins (Fig. 231B), or black and yellow striped (Fig. 231C); stringy black excrement on heavily infested plants; foliage ragged; plants sometimes stunted

    2. Cabbage looper - Green caterpillar with longitudinal white stripes; body up to 30 mm long, tapers toward the head; 3 pairs of legs near head; 3 pairs of fleshy prolegs (Fig. 232); young larva on underside of leaf; consumes tender leaf tissue leaving most veins intact

    3. Colorado potato beetle - Yellowish-brown, oval, convex beetle up to 14 mm long with 5 black longitudinal stripes on each wing cover and several black spots on the pronotum (area behind the head) (Fig. 233); feeds on leaves and terminal growth

    4. Flea beetles - Various species of tiny, darkly colored beetles 2.5 to 4.5 mm long; have solid color body or black body with pale yellow stripe on each wing cover (Fig. 234); tiny round holes in foliage

    5. Hornworms - Green to reddish-brown caterpillars up to 90 mm long with red or black anal horn; body with 7 diagonal or 8 V-shaped marks on each side; round black spiracles along side of body (Fig. 235); strips leaves from vines; infrequently feeds on fruit leaving large, open superficial scars

  3. Sap-sucking pests which cause leaf discoloration, leaf or fruit deformation, or defoliation

    1. Aphids - Soft-bodied, pear-shaped insects with a pair of dark cornicles and a cauda protruding from the abdomen; may be winged or wingless -- wingless forms most common; feed in colonies; cause discoloration or mottling of the foliage; excrete honeydew on which sooty mold grows

      1. Green peach aphid- Pale yellow to green wingless adult up to 2.4 mm long (Fig. 236A); winged adult with dark dorsal blotch on yellowish-green body (Fig. 236B); nymph with 3 dark lines on abdomen (Fig. 236C)

      2. Potato aphid - Adult and nymph both solid pink, green and pink mottled or light green with dark stripe; adult up to 3.5 mm long; long, slender cornicles about twice as long as cauda (Fig. 237)

    2. Greenhouse whitefly - White moth-like insect about 1.5 mm long; found in conjunction with tiny yellow crawlers and/or green, oval, flattened, immobile nymphs and pupae (Fig. 238A to F); leaves yellow and drop from plant; some plants stunted and unreproductive; black sooty mold often present on leaves

    3. Stink bug - Green or brown (nymph green with orange and black markings) shield-shaped insect; adult up to 19 mm long (Fig. 239); pierces buds and fruit causing buds to drop and fruit to be deformed

    4. Silverleaf whitefly - Adult is slightly smaller (0.96 mm in the female and 0.82 mm in the male), slightly more yellow in color and holds its wings roof-like at about a 45-degree angle; nymphs appear glassy to opaque yellowish and have a flattened and scale-like body with the margin near the leaf surface; pupa is flattened, dome-shaped and lack setae; plants stunted and nonreproductive with black sooty mold present

    5. Western flower thrips - Adult is about 1 mm long, varies from a pale yellow to dark brown and has a rounded, narrow abdomen; larvae are distinctly yellow; plants are distorted and have a silvery appearance; an important vector of spotted wilt virus

B. Pests that feed on roots or lower stems

  1. Cutworm - Fat, basically gray, brown, or black caterpillar 40 to 50 mm long when fully grown; 3 pairs of legs near head; 5 pairs of fleshy prolegs (Fig. 240); active at night; young caterpillar climbs on leaves, older caterpillar severs seedling stems near the ground; hides during the day in soil burrows at the bases of plants

  2. Southern potato wireworm - Slender, wire-like cylindrical larva with 3 pairs of short legs near the head and a pair of fleshy anal prolegs; white, cream, or yellow-gray body with red-orange head capsule; about 17 mm long when fully grown; closed notch in last abdominal segment (Fig. 241); ragged, irregular holes in roots

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