Anthracnose: This is a fungus disease that attacks the fruit as it is ripening. The first visible sign is a circular spot on the skin that is slightly sunken. The spots enlarge and turn black; the fruit rots. Extended periods of heat and humidity facilitate anthracnose growth. The fungus overwinters in diseased plant debris. Burpee Recommends: Plant resistant varieties, provide sufficient space between plants for good air circulation, avoid overhead watering which can spread the fungus spores, keep a clean garden, remove and discard all diseased plant material and rotate crops. Use a mulch to prevent spores from splashing from the soil onto plants.
Blight: Early Blight is a very common disease which causes brown concentric rings to appear on the lower leaves. The spots coalesce; the leaf turns brown and may drop off the stem. Leaf drop moves up the stem. Fruit does not grow to full size and is left exposed to possible sunburn/sunscald. This fungus overwinters in plant debris and weeds. Late Blight is another fungus disease that causes defoliation and fruit rot. Greasy, greenish-black, water soaked spots appear on the lower leaves. The spots enlarge and if the weather is wet they will look mildewed. Fruits develop dark rough spots. Rainy or cloudy days with temperatures of 70-80 degrees F and nights at 40- 60 degrees F provide ideal conditions for the rapid growth of this fungus. It is retarded by hot dry weather. The fungus is air-borne and can spread from diseased plants growing nearby. Burpee Recommends: Practice good garden hygiene at the end of the season and discard, do not compost, possibly diseased plants. Space plants to allow for adequate air circulation. Avoid overhead watering which may spread fungus spores. Plant in at least a 3 year rotation, do not alternate with plants in the same family (potatoes, peppers or eggplants). Plant resistant varieties such as ‘Cloudy Day’.
Septoria Leaf Spot: This disease causes severe losses in the Atlantic and Central states. It is most severe during rainy seasons in closely planted gardens. It usually appears when the plants begin to set fruit. Circular spots with gray centers and dark margins appear on the lower older leaves. Fungus spores are produced and darken the center of the spots. There is a progressive loss of foliage and fruits suffer from sunscald. Burpee Recommends: Remove and destroy Infected plant debris. Don't handle or brush against plants when they are wet. Rotate plantings. Remove weeds growing nearby.
Wilt Diseases: Bacterial wilt is evidenced by rapid wilting and the death of the plant caused by soil-borne bacteria. There is no forewarning of yellow or spotted leaves. When the affected stem is cut near the soil line, the area is dark and oozes a gray slime. The wilt does not attack the fruit. The bacteria live in the soil and enter the plant through the roots. Control Measures: Do not grow plants in the same family in that area or nearby for 4 or 5 years. Continue to apply generous amounts of healthy compost to soil while fallow or support other crops. Fusarium wilt is one of the most damaging tomato diseases because of its spread during periods of hot weather. The first symptom of fusarium is the appearance of a few yellow leaves or a slight drooping of the lower leaves. Caused by a soil-borne fungus, the fungus enters through the roots and passes up into the stem producing toxic substances. This fungus is similar to verticillium wilt but will affect first one side of the plant and then the other. Burpee Recommends: Destroy affected plants at the first sign of fusarium; rotate crops and plant resistant varieties. Verticillium wilt causes a wilting of the leaves and stems on several branches. Leaf margins cup upward, leaves turn yellow and drop off. If fruit is produced, it is usually smaller than normal. Like fusarium this will enter through the roots, migrating up the stem and plugging a plant's transport vessels. It is transmitted in the soil. It can also be spread by water and tools. Burpee Recommends: Practice at least a 4 year crop rotation. Remove and burn crop debris. Plant resistant varieties. Walnut wilt causes overall wilting of plants, or dwarfed growth, in close proximity to black walnut tree. Some or all plants in a planting may be affected. Burpee Recommends: Do not plant tomatoes near black walnut trees. These trees exude a toxin from their roots which kills many plants.
Virus (Various causes): The most characteristic sign of virus is tight and dark green mottling of the leaves. Young leaves may be bunched. Young plants may have a yellowish tone and become stunted. Fruit is usually not affected in outward appearance, but it may be smaller and scarcer. Leaflets may point upward and have a grayish cast. Burpee Recommends: Plant resistant varieties. This disease is readily spread by handling. Destroy diseased plants and the plants on either side. Never smoke in the garden as tobacco mosaic virus can be transmitted from a smoker's unwashed hands while handling plants.