This disease occurs on all continents on cucumber, gherkin, muskmelon, pumpkin, squash, vegetable marrow, and watermelon . The bacterium causes symptoms on the leaves, stems, blossoms and fruit. It is favored by warm, humid climates. It can cause fruit to drop or become spotted.
Older leaves are more susceptible than younger leaves.
On most host plants, leaf spots begin as small, water-soaked areas that enlarge until they are confined by a vein, giving them an angular appearance. The spots may have yellow borders. The tissue later turns gray to tan-brown and dies. As it dries and shrinks, it may tear, leaving ragged holes in the leaf. Female blossoms and young fruit may drop from infected vines.