Small beetles are causing big problems in Southern California. Two closely related species, the polyphagous shot hole borer and the Kuroshio shot hole borer (collectively referred to as invasive shot hole borers), have been attacking more than 60 species of trees. These invasive beetles create a series of tunnels, or galleries, where they lay eggs and cultivate a Fusarium fungus to use as a food source. The fungus causes branch dieback, general tree decline, and can result in tree death. The beetles have been found in Los Angeles, Orange, Riverside, San Bernardino, Ventura, Santa Barbara, and San Diego counties.
What should you look for?
Invasive shot hole.../h2>
What is Armillaria Root Rot?
Armillaria root rot is a severe fungal disease that affects trees, woody plants, and some herbaceous plants including palms and succulents.
Also known as oak root fungus, Armillaria root rot can rapidly kill trees and presents a challenge to management since infected woody roots can persist for years underground. No plants are completely immune to Armillaria root rot, so prevention is key. Deeply planted trees are often more susceptible to this disease.
The distinctive “honey mushrooms” growing from the base of a tree signals an infection, but they may not always be present. Other visible symptoms include flat cankers on the trunk, wilting, and canopy.../h2>
Palm trees are commonly seen in California, making some think about the tree-lined streets of Hollywood, or sitting by the pool somewhere. These tropical or subtropical trees are beautiful and varied, with many different types of palms, each adapted for different growing conditions and each with specific disease-causing pathogens that can attack it.
Palm trees, like other plants, are susceptible to pathogens that can weaken or even kill the tree. Diseases such as diamond scale, pink rot, Fusarium wilt, and others can reduce the leaf canopy, discolor leaves and trunk, and cause distortion, stunting or death.
If you have palm trees or care for palms as part of your work, it's important to identify and know about these...
Most citrus tree problems in home gardens can be solved by pruning the trees to allow better air flow and by controlling ants. Ants collect the honeydew produced by Asian citrus psyllid nymphs, mealybugs and/span>
[Originally published in the Fall 2018 issue of the Green Bulletin. Modified slightly from original.]
Invasive insects and diseases are threatening numerous tree species throughout the country. Impacts include tree mortality, destruction of forest and urban habitats, and other significant changes in forest ecosystems due to the decline or elimination of tree species. Many of these pests can be transported in inadequately-processed wood, including firewood and discarded wood debris left behind from tree care operations (Figure 1). Preventing the spread of these pests to new areas is critical for.../span>