Common Disease Problems
Alternaria Leaf Spot: Small, round reddish brown spots with white to gray centers for on the upper surface of the leaves. The lesions may encircle the stems and cause wilt. This disease is worse in warm, wet or very humid weather. Burpee Recommends: Avoid getting water on the foliage. Remove infected plant parts and do not work around wet plants. Provide plenty of air circulation. Contact your Cooperative Extension Service for fungicide recommendations.
Carrot Yellows: A virus disease that causes severe stunting and yellowing foliage. This disease is spread by leafhoppers. Burpee Recommends: Remove infected plants and control leafhoppers.
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.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. This is a serious problem in many Southern states. Burpee Recommends: Do not plant into infested soil. Grow resistant varieties. Try planting ‘Nema-Gone’ marigolds around your plants.
Root Rots: A number of pathogens cause root rots of seedlings as well as mature roots. Burpee Recommends: Practice crop rotation and do not plant related crops in the same area for several years. Pull up and discard infected plants. Make sure your soil has excellent drainage. Contact your Cooperative Extension Service for 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. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Carrot Rust Fly: This insect burrows into roots damaging the roots and leaving small white maggots. There are no above ground symptoms. Burpee Recommends: Sow for a fall crop rather than a spring crop. Consult your Cooperative Extension Service for insecticide recommendations.
Flea Beetles: These small hopping beetles feed on plant foliage. Burpee Recommends: Rotate crops with plants in a different plant family. Use floating row covers to prevent damage to young foliage.
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.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Why do I have carrot tops but no carrots? Carrots are a long season crop, they take a lot of time to grow their tap roots. If the greens of the carrot were cut during the growing season, energy is misdirected back into foliar growth instead of root growth. Protect your carrot greens. Poor soil will also inhibit root growth, as well as a phosphorus or potassium deficiency.
Why aren’t my carrots sweet? Carrots grown and harvested in warm weather are not as sweet as carrots grown in warm weather and harvested in cool weather. Fall harvested carrots are best because sugars from the foliage move into the root with the onset of cold.
Why are my carrots forked or deformed? Soil preparation is everything to good carrot root formation. Heavy clay soils and stones of any size will impair a carrot’s downward growth. Also too much nitrogen causes forking. Carrots like additional potassium and phosphorus, and not nitrogen.
Why are my carrot roots very hairy? Carrots are vulnerable to the disease “Aster Yellows”, this disease shows itself as deformed flower heads and abnormal root growth.
Can I start carrots indoors? No, carrots have a tap root and will not transplant well. They are easily direct sown in spring or summer.