Plant Diseases

Six circular cross-sections of a tree branch showing dark staining from a Bot canker infection.

What is Bot Canker?

November 5, 2025
By Belinda Messenger-Sikes
Botryosphaeria canker, sometimes called Bot canker, is a common fungal disease that can affect many tree species including ash, eucalyptus, fig, maple, pistachio, and walnut. Plants infected with this disease typically develop cankers (dark sunken lesions in the bark) and can lose branches. The whole…
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Nice looking lettuce
UC IPM on the South Central Coast: Article

2025 Fusarium wilt of lettuce variety trial field day - Soledad

August 19, 2025
By Christopher A Greer
Please join us for the 2025 Lettuce Fusarium Wilt Trial Field Day in Soledad - August 26, 2025 10 am - 12 pm. Trials include variety evaluations, steam treatment evaluations, and fungicide evaluations. Pre-registration is strongly suggested. Please see full article for additional info and directions.
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Discoloration and distortion of peppers from Cucumber Mosaic Virus. Dennis H. Hall, UC IPM Program
The Real Dirt: Article

A Virus in the Garden – Part II

July 1, 2025
A virus can reduce a plant’s growth, lower its yield, and result in inferior fruit, vegetables and flowers. Viruses are often very host specific. Recognizing symptoms can help you take appropriate action, where possible, to manage a virus and hopefully prevent its spread. The following are several viruses…
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Tomato leaves with signs of Tobacco Mosaic Virus. Jack Kelly Clark, UC IPM Program
The Real Dirt: Article

A Virus in the Garden

June 24, 2025
Most gardeners are aware of plant diseases that can wreak havoc in their gardens. If you grow fruit trees, you may be confronted with curled, reddened peach leaves (peach leaf curl fungus). If you grow apples or pears, your trees may sometimes look like they were scorched with a blow torch (fire blight…
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UC Cooperative Extension Sonoma County: Page

Threecornered alfalfa hopper degree day model

The threecornered alfalfa hopper (TCAH) is a vector of Grapevine red blotch virus that causes Grapevine red blotch disease in vineyards. A degree day model was developed to predict the ideal time frame for ground cover management to help reduce TCAH populations in vineyards.
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UC Cooperative Extension Imperial County: Page

Plant Pathology

Program OverviewThe Plant Pathology Program provides applied research and outreach to support agricultural production across Imperial, Riverside, and San Diego counties. This tri-county region encompasses a wide diversity of crops and growing conditions—from the desert-irrigated systems of Imperial Valley to…
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