Plant Diseases

Reflections on thrips and INSV during the 2025 Lettuce Season Dylan J. Beal, Daniel K. Hasegawa, Yu-Chen Wang INSV: Early Spring and Summer: isolated, small INSV outbreaks were observed. These outbreaks were associated with adjacent, unmanaged weedy sites.Late Summer and early Fall: more…

Fungal diseases plague many different kinds of plants and their gardeners.  Fungal diseases tend to be persistent and can be difficult to manage.  Powdery mildew is one such disease.  It includes multiple fungal species and affects many different types of plants.  Powdery mildew…

If you have peach or nectarine trees, winter is the time to spray them to prevent peach leaf curl. Peach leaf curl is a fungal disease that attacks peaches and nectarines. It appears in spring, causing new leaves to become reddish, puckered and severely distorted. This disease is caused by the fungus…

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…

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.

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…

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…

Learn about one of the major diseases associated with poor water management, Phytophthora root and crown rot.