How to Manage Pests

Pests in Gardens and Landscapes

Leaf spot diseases

Many fungi cause leaf spots on different hosts. Spots may vary from small discrete dots and raised areas to irregular yellow or brownish patches that cover much of the leaf surface. Leaves may fall off the tree if the problem is severe, but these pathogens rarely cause long-term damage to trees. Similar spots can be caused by bacterial pathogens, insects and mites, or abiotic factors on some plants.


In most cases, infections can be tolerated. Remove fallen leaves and debris promptly. Many of the pathogens are favored by moisture, so avoid overhead sprinklers and irrigate early in the day so that the foliage dries more quickly. Generally, fungicide treatment is not warranted.

Leaf spot on Freesia
Leaf spot on freesia

Phyllosticta  leaf spot
Phyllosticta leaf spot on maple

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