- Author: Belinda J. Messenger-Sikes
Because mistletoes can damage trees, you may decide to do something about mistletoes infesting your trees. The first step is to find out whether you're dealing with broadleaf or dwarf mistletoe. Mistletoes differ in their life cycles, the damage they cause and management methods. UC Cooperative Extension Advisors Igor Lacan (San Mateo and San Francisco Counties), Steven Swain (Marin County) and Ed Perry (Stanislaus County, retired) have updated and expanded Pest Notes: Mistletoes. It includes more about identification of broadleaf and dwarf mistletoe, the latest information about where specific mistletoes grow in California, as well as details about how dwarf mistletoe infest trees and under what circumstances. The publication has management options for both types of mistletoes, information on community-based mistletoe management, a new section about the ecological benefits of broadleaf mistletoes, and new references.
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- Author: Elaine Lander
Mistletoe is a familiar sight of the season, often found wrapped in ribbon and hung for certain festivities this time of year. But did you know it is actually a parasitic plant that grows on a number of landscape trees in California?
Both types of mistletoe grow through tree bark and into the tree's tissue, living off the host tree. Healthy trees can typically tolerate a few mistletoe infections although individual branches may be weakened by the parasite. Trees with a heavy infestation can be stunted or even killed if they are stressed by drought or disease.
What can be done about unwelcome mistletoe? The most effective way to control mistletoe and prevent its spread is to prune out infected branches as soon as possible. If mistletoe is infecting a major branch or trunk, you can cut off the mistletoe and wrap the area to exclude light. See our Pest Notes: Mistletoe for additional instructions.
Reducing mistletoe is a community effort since it spreads easily from tree to tree. So if you find yourself underneath some mistletoe this season, be sure to share this information with your neighbor!
When people think of parasites, often what comes to mind are blood-sucking insects like bed bugs, head lice, and fleas or other bodily invaders on or in humans and other animals. But plants can have parasites too. Most of us are familiar with mistletoe but there is another parasitic plant you may not have heard about: dodder.
There are several species of dodder native to California but they are not as problematic as a particularly invasive species, Japanese dodder, Cuscuta japonica. This invasive plant pest has thick stems that resemble spaghetti. It grows larger and faster than native dodders and can even cover entire trees or shrubs.
Japanese dodder is spread when pieces of it are broken off and moved about by birds or other animals. It can also be spread through human activities such as pruning, composting, and the improper disposal of infected plant material.
For more information about Japanese dodder and other dodders, consult the Pest Notes: Dodder.
There are two types of mistletoe: broadleaf and dwarf. Broadleaf mistletoe is evergreen and can be found growing on common trees such as flowering pear, ash, and birch, while dwarf mistletoe attacks firs, pines, and other conifers.
Mistletoe robs trees of both water and nutrients. If you see small amounts of mistletoe growing on healthy trees in your landscape, it's probably not a cause for concern. However, if a tree is heavily infested, individual branches may be weakened or killed, and trees affected by drought or disease may be stunted or even die.
Some trees are more susceptible to mistletoe infestation than others. For a list of less-susceptible trees and what to do about heavy mistletoe infections, read the UC IPM Pest Notes: Mistletoe.