With the current temperatures in the 60's and 70's and cloudy skies, conditions are conducive for late blight to occur on tomato and potato. In fact, late blight has been reported on potato and tomato in Alabama recently. Typically, we don't see late blight on tomato until late summer, but because conditions are conducive, it's a good idea to scout.
Late blight is caused by the oomycete Phytophthora infestans. It is a fungal-like organism that is particularly good at spreading through air currents. Cool, wet conditions favor this pathogen, if it is present in the area. On tomato and potato, it can be extremely aggressive under these conditions, so it is important to apply preventative fungicides or use resistant varieties. Symptoms on tomato include light brown lesions sometimes with a light green halo. Lesions will attack new growth first, but all parts of the plant, including fruit, can be affected. More information can be found on the tomato late blight and potato late blight disease factsheets.
