Pear trellis rust is caused by the fungus Gymnosporangium sabinae. It was introduced into the United States from Europe in the 1990s and has been progressively spreading through states in both the East and West. The disease affects common pear,…

Adult sawflies are often similar in appearance to flies or wasps. The larvae are also similar, though sawflies have one simple eye on each side of the head and five or more pairs of prolegs on their abdomen, whereas butterflies/moths…

Bacterial leaf scorch (BLS) is caused by the bacterium Xylella fastidiosa. This disease impacts certain shade trees resulting in uneven ‘scorching’ of leaf margins in late summer and early fall. The bacteria themselves live in the xylem tissue and gather…

Two common causes of root disease in California are species of the fungus Armillaria and species of Phytophthora, which are fungus-like organisms. There are many differences between the two pathogens, but effective management of both involves creating growing conditions that…