Bob Mulrooney, Extension Plant Pathologist; firstname.lastname@example.org
There have been several samples from DE and MD with angular leafspot that have been diagnosed this spring. As you can see from the picture this bacterial leafspot produces angular watersoaked spots initially (Figure 1) that turn dark and eventually brown with time (Figure 2). The bacteria are limited by the vein pattern in the leaf which gives it the diagnostic angular pattern. This disease can cause leaf loss, and when conditions are very favorable during fruit set, the calyx can become infected and that can reduce the marketability of the fruit. Wet conditions favor the disease, especially if irrigation is needed for frost protection. The bacteria that cause the spring symptoms come from systemically infected overwintered plants and dead leaves, and from infected transplants. Copper sprays can be effective in limiting spread once it is identified but over-application can be phytotoxic, so be careful. Prevention of angular leafspot in the plant nursery and its dissemination in transplants is crucial to controlling this disease.
Figure 1. Watersoaking symptoms
Figure 2. Angular leafspot symptoms