The angular leaf spot symptom start as small brown to black lesions which are angular in shape on most cucurbits, and in some cases not angular in shape with or without a yellow halo.
The disease can cause severe transplant damage under ideal conditions. The causal bacterium can be seed-borne, survive in infected transplants and on plant debris/weeds.
Water soaking is an early indication of this bacterial disease. Flip the leaves to see water-soaking, but it can be also noticed on the top side of the leaves.
The lesions can be noticed at both the margin of the leaves and leaf lamina as seen here on watermelon leaves. The disease spreads easily during splashing rain.
Cool and wet weather conditions especially during early spring and late fall favor occurrence of angular leaf spot. The disease can cause delayed maturity of fruits due the impact on transplants.
In severe cases the disease causes major leaf damage and complete loss of transplants especially during early stages of growth on cantaloupe, cucumber, squash and watermelon.