Plant Diseases

Anthracnose is a group of fungal diseases that infect many trees and shrubs, causing dark lesions on leaves and cankers on twigs and stems. In some areas of California, vegetables and turfgrass can also be infected with anthracnose. Symptoms of anthracnose vary by plant host and weather conditions.

As you practice social distancing during COVID-19, you may find yourself spending more time in the garden. As we move into nice weather, we are sharing a few gardening tips for pest management. Check for signs of powdery mildew on fruit trees, landscape ornamentals, and vegetables.

Roses in the garden can be infected with a variety of bacteria, fungi, and viruses, leading to diseases like powdery mildew and rust. Roses may also be damaged by nutrient deficiencies and other environmental problems.

Armillaria root rot is a severe fungal disease that affects trees, woody plants, and some herbaceous plants including palms and succulents.

The California Department of Food and Agriculture has declared a quarantine following the detection of Huanglongbing (HLB) in multiple residential citrus trees in Corona (Riverside County). This is the first time HLB has been detected in Corona.

A quarantine has been declared following the detection of the citrus disease Huanglongbing (HLB), or citrus greening, in a single citrus tree in an unincorporated area of San Bernardino County, near Montclair. This is the first time the plant disease has been detected in San Bernardino County.

Landscape trees provide welcome shade, fruit, homes for wildlife, and even a place for kids to climb. But if the wood is damaged, disease-causing fungi can infect the tree. A number of fungal diseases decay wood in both tree branches and trunks, weakening and sometimes killing the tree.

Palm trees are commonly seen in California, making some think about the tree-lined streets of Hollywood, or sitting by the pool somewhere.

If you are puzzled by curling leaves on plants in your garden or landscape, you may need to do some detective work to figure out the cause. Curling leaves can be caused by many problems, including insect damage, disease, abiotic disorders, or even herbicides.

[From the Spring issue of the UC IPM Retail Nursery & Garden Center News] Most disorders impacting landscape trees result from abiotic (non-living) disorders rather than attacks from biotic (living) pests like plant pathogens, insects, and vertebrates.