Grey Leaf Spot is caused by the fungi Stephylium solani. Grey Leaf Spot is a fungal disease that causes lesions on the generally older leaves on tomato plants in form of brown or black specks. The specks change color over time and grow larger (1-2 mm). They can stay brown or turn into spots that have a grey center with surrounded by yellow. Holes (shot holes) can go all the way through on the leaves. There can be several spots on a leaf but they don’t generally fuse together and remain separate on the leaf that they are on. The spots on a leaf may make the leaf itself change to yellow, then brown and fall off the plant.