These diseases are managed primarily by judicious use of fungicides. The use of Tomcast, a computerized disease-forecasting system based on the weather, may allow fewer fungicide sprays to be made than with conventional calendar applications. Bacterial spot causes circular to irregular necrotic spots, usually surrounded by chlorotic halos, on leaves, petioles, and stems, and blight of flower sepals and peduncles. A necrotic 'burn' of the leaf margins may also occur. On fruit, spots are circular to irregular, and often raised or crusty.
Defoliation occurs commonly.
Bacterial speck symptoms are similar to spot symptoms on foliage, but fruit spots are smaller and flatter. Bacterial canker causes a firing of leaf margins, leaf spots, stunting and death of plants, and 'bird's-eye' symptoms on the fruit. In the laboratory, a preliminary diagnosis of bacterial disease is made by examining pieces of a lesion in water by using a light microscope. The presence of bacterial ooze or steaming is the first presumptive evidence of a bacterial disease. Bacteria are then cultured on specialized media for further identification.