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How to Manage Pests

Pests in Gardens and Landscapes

Late blight—Phytophthora infestans

Phytophthora infestans has a wide host range, including tomato, potato, pepper, and eggplant. On leaves, late blight lesions typically first appear as irregular, small pale to dark green water-soaked spots that are surrounded by a zone of yellowish tissue. Lesions may expand rapidly and become brown to purplish black. White sporulation of the fungus may be observed at the periphery of lesions, principally on the underside of leaves. On stems and petioles, lesions are brown to black and may also support sporulation of the fungus. Fruit discoloration usually begins on the upper side of the fruit. Affected fruit remain firm.

Solutions

Avoid sprinkler irrigation. Destroy all tomato, potato, eggplant, and pepper debris after harvest.

Late blight infection on tomato leaves
Late blight infection on tomato leaves

Tomato fruit discoloration
Tomato fruit discoloration


Statewide IPM Program, Agriculture and Natural Resources, University of California
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