Late blight is caused by a fungus, Phytophthora infestans. The spores of this fungus may have come to your yard in the fog, they may be present in your yard in the garden soil, or you may have bought them at the garden store and brought them home on the seedling tomatoes. Usually the leaf blight is the first evidence of disease presence. But leaf and fruit infection can occur at the same time.

 

To control late blight, keep the plants as dry as possible. Do not irrigate with a sprinkler. Use furrow irrigation or drip hose. Remove the dead and dying leaves and dispose of them in your green waste. Do not leave them on the ground under the tomato plants. Finally, spray your plants every seven to ten days.