There are several diseases that can affect your carrot crops. Regularly check your plants for signs of disease so that you can eliminate them and protect the rest of your garden.
Simple Solutions for Most Diseases
Do not plant carrots in the same location more than once every 3 years. By moving your carrot seeds to different locations, you can help prevent most diseases that are caused by soil.
A simple natural fungicide can cure most fungal diseases that affect your carrots. Fungicide can be found at most lawn and garden stores.
Thinning your plants or overcrowding your plants can also cause disease or lack of growth in your carrots. Make sure that you plant your crops evenly as specified by growers of each variety. Also, avoid planting them in soil with excessive nitrogen.
Aster Yellow Disease
If your carrots have stunted, yellow leaves, they might be affected by aster leafhoppers. To help prevent this disease, you should take steps to keep your garden weed free.
Soil Fungus: Root Rot Disease and 'Damping-Off' Disease
Root rot or black root rot is a fungus that attacks carrots in infected soil. Unfortunately, this disease is hard to notice until you after the harvest. To prevent root rot after harvest, thoroughly clean carrots and store them in a dry, cool place.
Damping-off disease is caused by soil-living fungus. Cool air and moisture can worsen the disease and help it spread to other plants. Younger plants are most susceptible and will show symptoms of withering, brown leaves or sudden death. To prevent this damping-off disease from killing your carrots or spreading, use well-drained soil so that the disease can not survive.
Leaf Fungus: Leaf Blight, Leaf Spot and Powdery Mildew
Also caused by fungus, leaf blight will attack your carrots later in the growing season. This disease looks like brown spots of decay that have yellow centers on the leaves, or the leaves may just wither and die. Immediately remove all withered leaves and to dispose of them. Do not let them remain on the ground as the fungus will spread, even if left alone over the winter. If you do not properly remove plants that have suffered leaf blight, the disease will spread to your crops in the next growing season. This fungus is known to spore most in high humid climates.
Another fungus that attacks carrot leaves is called leaf spot. This will appear in small dark circles. This disease also is most common later in the growing season.
If you see white or gray powder on your leaves, your carrots may have a powdery mildew disease. Like other fungal diseases, powdery mildew must be treated with a natural fungicide. Properly dispose of all infected plants as soon as possible.
If your carrots have growth cracks, it may be because you have an inefficient irrigation technique. It is not good to have the soil too wet or too dry. Make sure to water often, but the soil should drain well.
If your carrots have green tops, they are probably planted too close to the top of the soil. The tops of carrots will turn green if they have too much exposure to the sun. You can prevent this problem by adding 3 inches of mulch after your seedlings appear.