How to Manage Pests

Pests in Gardens and Landscapes

Angular leaf spot—Pseudomonas syringae pv. lachrymans

Angular leaf spot occurs most commonly on cucumber, but is also found on melons in California. Lesions on the foliage begin as water-soaked spots that later turn gray or tan. Spots may initially develop a yellow halo. As the affected tissue dries, the internal tissue may fall out, giving the leaf a tattered appearance. The lesions are delimited by veins, giving them an angular shape. Fruit lesions are usually superficial.

Solutions

The bacterium survives on infected plant debris in the soil or on seed. Rain or overhead irrigation leads to rapid spread. Limit the use of overhead sprinklers. Pick fruit when the vines are dry to prevent spread in the field. Resistant cucumber varieties are available. Use pathogen-free seed and rotate out of cucurbits.

 

Spotting of cucumber leaves
Spotting of cucumber leaves


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

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