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Broccoli - 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 that are up to 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. About the time the cherries bloom, 1/4 inch long adult flies emerge from the soil and lay their eggs at base of plants in surrounding soil. The legless larvae feed on host plants 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. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

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: Keep debris removed. Rotate location of planting from year to year. Dust with *Rotenone * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

Problem: Aphids
Affected Area: Leaf

Description: Small Insects found on new stems and the underside of the leaf. Usually green. They suck fluids from the plant leaving a honey dew substance behind. Leaves turn pale yellow and tend to twist and roll up.

Control: A layer of aluminum foil under plants reflects light to underside of leaves and may deter aphids. Insecticidal soaps or a strong stream of water or most labeled insecticides like *Diazinon or Sevin. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

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. Dispose of them completely 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 and become defoliated if more mature.

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



Wash broccoli well; loopers (green caterpillars of a color that closely matches vegetable) may be hiding. A short soak in salt water will usually dislodge them.