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Cabbage - Diseases, Pests and Problems

Basic Information

Problem: Cabbage worms, Cabbage loopers
Affected Area: Leaf

Description: Loopers are caterpillars that are generally green or greyish, taking on the color of the host plant. They may blend well and be difficult to see. They eventually develop into white- or yellow-winged butterflies often seen fluttering about the plants. Caterpillars feed on the underside of leaves leaving ragged holes sometimes to the extent that plants starve and die.

Control: Spray with Bacillus thuringiensis (Bt) Comercially available as Dipel or Thuricide.) Cover with remay or similiar product in spring.

Problem: Cutworms
Affected Area: Stem

Description: Plants chewed off just above ground level. Cutworms are caterpillars 1 1/2" long and mottled or striped green, brown or gray. When they are disturbed, they roll up in a coil. They usually position themselves at the moisture line in the soil moving up and down according to the water content. If the soil surface is dry, they will be found a couple of inches below the surface where the moisture begins. When newly watered, they will be at the surface.

Control: Put cardboard collar around new transplants to extend 1" to 2" above and below soil level.

Problem: Root Maggots
Affected Area: Root

Description: Leaves wilt and growth is stunted. Insect is common, white, root feeding maggot. 1/4" long adult flies emerge from the soil about the time cherries bloom and lay eggs at base of plants in surrounding soil. Legless larvae feeds on host plant for three weeks, riddling the roots with brown tunnels before they pupate Two or three generations can occur each growing season.

Control: Use Diazinon before planting as a soil treatment. Rotate from year to year.

Problem: Flea Beetle
Affected Area: Leaf and Root

Description: Tiny holes ?pinholes? chewed in leaves by adult insect. Adult insects are 1/16" long, hard shelled, shiny, dark-colored beetles that jump when disturbed. Slender, whitish, cylindrical larvae feed in or on roots but root damage is generally minimal.

Control: Dust with Rotenone. Keep debris removed. Rotate location of planting from year to year.

Problem: Aphids
Affected Area: Leaf

Description: Green, red black or white insects that cause curled yellow leaves and exude a honeydew substance

Control: Insecticidal soaps or a strong stream of water or most labeled insecticides like Diazinon or Sevin. A layer of aluminum foil under plants reflects light to underside of leaves making them an undesirable habitat for aphids.

Problem: Slugs and Snails
Affected Area: Entire plant

Description: Large portions of young plants missing.

Control: Slugs and snails are very susceptible to desiccation (drying) and require a moist, shady place to live. Cultural practices which promote a sunny, dry environment will discourage them. Avoid too-frequent waterings allowing soil surface to dry out between irrigations. Keep garden free of debris, boards, bricks, and stones where they hide. Hand picking these pests is very effective. Create ?traps? for hand picking by laying boards in the garden. Slugs and snails will congregate under them. Lift the boards each morning and collect the slugs and snails. Kill and dispose of them in garbage as they will crawl back if tossed out of the garden and eggs inside dead pests can still hatch to produce more of these pests. Slug and snail bait containing metaldehyde can be placed near food plants as long as they do not contact edible portions of the crop. Most effective when moistened, but not water logged. Snail bait attracts slugs and snails from several feet away so bait stations are effective. Stations help protect birds, pets and other non-target animals which are also attracted to the bait. Place small piles of bit under a slightly propped up board or use container such as a cottage cheese or yogurt carton. Bury carton to the mouth of the container. Place small amount of commercial bait inside and moisten with apple juice, orange juice or water. Cut hole in lid to allow access and place lid on container. Containers may also hold beer or yeast water to attract slugs and snails in where they drown. Place bait stations wherever slugs and snails are active or around perimeter of garden.

Problem: Damping Off
Affected Area: Seedling

Description: Young seedlings wilt and die

Control: Use treated seed and let soil dry out between waterings

Problem: Bacterial soft rot
Affected Area: Leaf

Description: Leaves turn yellow (chlorotic) beginning at margins and spreading inwards. Veins within area turn black. Infection enters main stem turning the inside black.. Plants either die or are dwarfed when young, become defoliated if more mature.

Control: Plant resistant varieties and rotate crops from year to year.

Problem: Alternaria Leaf spot
Affected Area: Leaf

Description: During wet seasons, a brown velvety spore-bearing lesion appears on the older leaves. Leaf spots begin as a small dark spot and enlarge to form a large circular lesion forming a bull's-eye pattern.

Control: The best form of control is to apply fungicides.

Problem: Aphids
Affected Area: Leaf

Description: Aphids develop as colonies of small soft-bodied, usually gray-green, insects on leaves causing deformed or curled leaves. Sticky honeydew may be present.

Control: Aphids are the most difficult insect to control on Cole Crops. Insecticidal soaps or a strong stream of water or most labeled insecticides like Diazinon or Sevin. A layer of aluminum foil under plants reflects light to underside of leaves making them an undesirable habitat for aphids.

Problem: Black Rot
Affected Area: Leaf

Description: Humid rainy conditions are ideal for the development of black rot. Yellow to light brown patches appear at the margins of leaves and later black veins develop within the yellowed areas. Affected areas turn brown and dry out, often leaving a triangular-shaped lesion on the leaf margin with one point of the triangle directed toward the midrib.

Control: The best form of control is to avoid sprinkler irrigation and plant tested seed.

Problem: Cabbage maggot
Affected Area: Roots

Description: Cabbage maggot is characterized by feeding injury (engraving) on the surface of roots, or tunneling through the roots of young plants. These plants fail to grow properly and may wilt and die.

Control: NA

Problem: Clubroot
Affected Area: Leaf and Root

Description: Although there is no economical way to eliminate clubroot, rotation can significantly reduce the disease along with liming in alkaline soils. The first above ground symptom is the slight wilting or flagging of leaves during the day and recovering at night. Roots of most crucifers infected at a single site are spindle shaped, but multiple infections of the same root cause extreme swelling and distortion. It is spread by animals, water, transplanting, and movement of infested soil.

Control: NA

Problem: Diamondback moth caterpillar
Affected Area: Leaf

Description: This caterpillar causes small holes in the leaves and weaves cocoons about 1/3 inch long on the leaves.

Control: The best form of control is to apply an effective insecticide.

Problem: Downy Mildew
Affected Area: Leaf, Stem, and Flower

Description: The most common symptom of downy mildew is grayish white, fluffy growth on the underside of the leaves and some florets may develop black streaks or dark purple spots during cool, moist weather. Irregular, yellow to brown spots develop on both leaf surfaces and may spread to the stems and flower parts.

Control: Repeated chemical applications are the best way to control the disease as well as the use of resistant cultivars where they are available.

Problem: Fusarium Wilt
Affected Area: Leaf

Description: The yellowing of leaves are the first symptom of fusarium wilt which eventually results in the plant wilting and dying. Soon after yellowing appears, the water conducting tissue becomes reddish brown, usually first on one side of the stem. The disease is most common in the summer months.

Control: Fumigation and choosing resistant cultivars help control fusarium wilt in plants and in soil.

Problem: Harlequin bug
Affected Area: Leaf and Wilt

Description: Harlequin bug is characterized by an attractive shield-shaped insect usually black with bright red, yellow or orange markings. Plants become wilted and have distorted leaves that turn brown.

Control: The best form of control is to handpick the bugs and their egg masses off of infected plants.

Problem: Sclerotinia Rot
Affected Area: Leaf and Head

Description: The lower leaves wilt first, and hard, black sclerotia on white, cottony mycelium develops on the underside of the lower leaves. Eventually, the whole head wilts, yellows, and drops due to sclerotinia drop disease. Cool moist weather enhances the spread and development of the infection.

Control: Management methods for Sclerotinia minor include deep plowing, keeping the soil bed surface dry, removing infected crop residues, and applying fungicides as soon after thinning as possible. Management for Sclerotinia sclerotiorum includes keeping bed surfaces dry, removing weedy areas around the fields, and applying fungicides, although they may differ from those used for Sclerotinia minor.

Problem: Tipburn
Affected Area: Leaf

Description: Although symptoms are not visual from the outside of plant, the edges of leaves on the inside are brown. Necrosis may occur only along the margin or along the whole edge of the leaf.

Control: The best forms of control include applying nitrogen in nitrate (NO3 -) forms rather than ammonium (NH4+) to fertilize, avoid water stress, and have good irrigation practices.



Buy transplants that are not leggy.