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Seedlings sometimes fail to sprout or die soon after. Seeds may rot before germinating, shoots may decay before they emerge, or stems of seedlings may be attacked near the soil line, causing young plants to collapse. These diseases are collectively called “damping off,” likely caused by a number of soil…
Downy mildews, including Peronospora and Plasmopara spp., are pathogenic water molds (oomycetes) that primarily damage foliage. Hosts include cane berries, roses, various herbaceous ornamentals, and many fruit, grain, and vegetable crops. Category Fungi Signs/Symptoms Downy mildew causes pale green to…
Fire blight is a common and frequently destructive disease of pome fruit trees and related plants. The disease can destroy limbs and even entire shrubs or trees. Caused by the bacterium Erwinia amylovora. Pear (Pyrus species) and quince (Cydonia) are extremely susceptible. Apple, crabapple …
Fungus. Various host-specific forms of Fusarium oxysporum can kill infected plants. Hosts include asparagus, bean, cabbage, cantaloupe, pea, tomato, and watermelon. There are many varieties of host plants with resistance to Fusarium wilt.Like verticillium, causes leaf…
Late blight of potato was responsible for the Irish potato famine of the late 1840s. Late blight is caused by the oomycete Phytophthora infestans. Oomycetes are fungus-like organisms also called water molds, but they are not true fungi. Category Fungi Signs/Symptoms Lesions appear as small dark green…
Powdery mildew is a common disease on many types of plants and is prevalent in many areas of California. Infection occurs when fungus contacts a suitable host and environmental conditions are favorable. Infections spread as spores produced in these white patches move by wind and splashing rain to other…
Virus transmitted by aphids. After feeding on an infected plant, aphids are only able to transmit this virus for very short periods of time (minutes to a few hours). In general, spread of potyviruses in the field occurs when aphid activity is high and is often very rapid and localized. Category Virus …
The UC Master Gardeners of Sonoma County are available to help Sonoma County home gardeners with a wide variety of common problems seen in the home garden. We offer research-based information about pest management and cultural gardening practices to help gardeners achieve success with a healthy and…
In the Bay Area, the most frequently found ants populating our gardens and invading our homes are Argentine ants. Argentine ants are small (1/8”), and their queens are slightly larger. Their bodies are constricted, giving them an appearance of a thin waist, which distinguishes them from termites. …
