If you’ve ever tried your hand at growing heirloom tomatoes … then chances are you’ve run across Early Tomato Blight.

Early tomato blight is an infection (caused by the fungus Alternaria solani) that starts out as dark brown spots, yellowing leaves, and eventually spreads quite rapidly through the crop killing the leaves and fruits if it has a chance. The fungus spores form in hot, humid weather and then wait for a nice, cool, wet evening to start destroying the plants. We’ve definitely had more than ideal weather for blight this summer. It shows up just as the plants are starting to set fruit – and once the infection starts, it is nearly impossible to stop from spreading. If you’re growing organically and aren’t planning on dousing them with fungicide, that is.