Common Disease Problems

Aster Yellows: Plants are stunted, develop witch's brooms (excessive growth), petals turn green and become deformed. This virus-like condition is spread by leafhoppers. Burpee Recommends: Remove infected plants and control leafhoppers. Remove weeds in the area which serve as alternate hosts to the disease.

Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water and rinse in a ten per cent bleach solution after use.

Downy Mildew: This fungus causes whitish gray patches on the undersides and eventually both sides of the leaves. Burpee Recommends: Rotate crops. Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Do not work around plants when they are wet.

Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.

Rust: A number of fungus diseases that rust colored spots on foliage, stalks and husks. Burpee Recommends: Practice crop rotation. Remove infected plants. Contact your Cooperative Extension Service for fungicide recommendations.

Common Pest and Cultural Problems

Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Aphids are only a problem if the plants are stressed. Alyssum is used as a trap crop for lettuce. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.

Cutworms: These insects cut off the seedlings at the soil level. Burpee Recommends: Place a paper cup collar (use a coffee cut with the bottom cut out) around the base of the plant. They are usually mostly a problem with young seedlings. You can also control by handpicking and controlling weeds, where they lay their eggs.

Leafhoppers: Leafhoppers cause injury to leaves and stunt growth. They also spread disease. Burpee Recommends: Remove plant debris. Use insecticidal soaps. Consult your Cooperative Extension Service for other insecticide recommendations.

Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.

Stalk Borer: The larvae of this insect tunnel up and down inside the plant stem causing the plants to wilt. By the time the plant wilts it is too late to save it. The larva is 1.5 inches long, greyish brown with one dorsal stripe and two lateral stripes on each side. The lateral stripes on the front half are interrupted and the lower brown stripe extends forward onto the side of the head. The eggs hatch in May to early June, after the moth lays them the previous September or October. Burpee Recommends: Remove and destroy all plant debris and nearby weeds.

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