Tomato plants that have spots that start as small, dark brown to black areas, and are turning yellow on the lower part of the plant, may indicate the presence of early blight. As the spot develops, a concentric ring pattern can frequently be detected. This is the most diagnostic symptom of the disease and is the source of the name, “target spot,” that is frequently found in popular garden books. As the disease progresses, leaves yellow, then drop. In severe cases, all the foliage can be blighted and premature leaf drop result. This in turn results in leaving the fruit exposed and sunscald results.
- Affects
- Level of Concern
- Gardeners take note
- What months
- Jun–Sep
- Treatment / Useful Links
When first noticed, removed diseased leaves to reduce infection. Do not remove so many that it leaves the plant susceptible to sunscald. Keep plant foliage off of the ground, using mulches and/or stakes. Space plants to allow for good air movement and drying of the leaves. Avoid overhead watering, which can splash the disease-causing spores from infected to un-infected material. Do not over fertilize with nitrogen. Improve drainage and cultivate around plants to hasten drying at the crown. Do not work around plants when leaves are wet. Crop rotation can help disease control from year to year. Helpful link: http://www.colostate.edu/Depts/CoopExt/4DMG/Pest s/Diseases/blight1.htm