Bacterial Spot (bacterial - Xanthomonas campestris pv. vesicatoria)
Infected leaves show small, brown, water soaked, circular spots about one-eighth inch in diameter. The spots may have a yellow halo. This is because the centers dry out and frequently tear. on older plants the leaflet infection is mostly on older leaves and may cause serious defoliation. The most striking symptoms are on the green fruit. Small, water-soaked spots first appear which later become raised and enlarge
until they are one-eighth to one-fourth inch in diameter. Centers of these lesions become light brown and slightly sunken with a rough, scabby surface. Ripe fruits are not susceptible to the disease.. but the surface of the seed becomes contaminated with the bacteria The organism may also alternate hosts over winter, by getting on volunteer tomato plants and on infected plant debris. Moist weather and splattering rains are ecential to disease development. Most outbreaks of the disease can be traced back to heavy rainstorms that occur in the area. the Infection of the leaves may occur through natural openings. The infection of other fruits may occur through insect punctures, sandblasting and other mechanical injury means. Bacterial spot is difficult to control once it appears in the field.
Late Blight (fungal - Phytophthora infestans)
Lesions produced on the leaves are at first large, greenish-black, and water-soaked. These areas enlarge, becoming brown, and under humid conditions, develop a white moldy growth near the edge of the diseased area on the lower surface of the leaves or on stems. The disease spreads rapidly under humid conditions, destroying large areas of tissue. Fruit lesions occur as large, green to dark brown, mostly on the upper half of the fruit. Also, a white moldy growth may appear on fruits in humid conditions. The fungus produces an abundant number of spores which may be splashed by rains or be airborne. These spores infect healthy leaves, stems and fruit if weather conditions are good. Ideal conditions for late blight development are cool nights, moderately warm days, abundant moisture. Hot and dry weather reduces disease development.
Gray Leaf Spot (fungal : Stemphylium solani)
First infection appears as small, brownish-black specks on the lower leaves that extend through to the under surface of the leaf. These spots usually remain small, but may enlarge until they are about one-eighth inch in diameter. The spots become glazed and the centers crack. Infected leaves usually die and fall off. spots may also form on the stems of the host plant.
Causal Agent(s): (fungal - Fulvia (Cladosporium) fulvum)
Leaf mold is usually first observed on older leaves near the soil where air movement is poor and
humidity is high. At first, diffuse whitish spots appear on the upper surfaces of older leaves; these
rapidly enlarge and become yellow. Under humid conditions, the lower surface of these spots