How Can I Control Mistletoe?

Do you want to try controlling mistletoe with mechanical control methods?

Has mistletoe infected secondary branches that can be pruned off?

Do you want to try controlling mistletoe with the chemical control method?

The most effective way to control mistletoe and prevent its spread is to prune out infected branches, if possible, as soon as the parasite appears. Using thinning-type pruning cuts, remove infected branches at their point of origin or back to large lateral branches. Infected branches need to be cut at least one foot below the point of mistletoe attachment to completely remove embedded haustoria. Done properly, limb removal for mistletoe control can maintain or even improve tree structure.

Mistletoes infecting a major branch or the trunk where it cannot be pruned may be controlled by cutting off the mistletoe flush with the limb or trunk. Then wrap the area with a few layers of wide, black polyethylene to exclude light. Use twine or tape to secure the plastic to the limb, but do not wrap it too tightly or the branch may be damaged. In some tree species, callus tissue will form under the plastic, further weakening the limb. Broadleaf mistletoe requires light and will die within a couple of years without it. It may be necessary to repeat this treatment, especially if the wrapping becomes detached or if the mistletoe does not die.

The plant growth regulator ethephon may be used as directed by the label to control mistletoe in dormant host trees. To be effective, the spray must thoroughly wet the mistletoe foliage. The ideal time to treat is in spring as temperatures begin to warm, but before the tree begins to grow new leaves. Daytime temperatures must be above 65 degrees Fahrenheit for good results. Spray only the individual mistletoe plants, not the entire tree. By treating when trees are dormant, the tree foliage will not get in the way of the treatment and the mistletoe is more visible than when leaves are on the tree.

Some tree species appear resistant to broadleaf mistletoe. Bradford flowering pear, Chinese pistache, crape myrtle, eucalyptus, ginkgo, golden rain tree, liquidambar, sycamore, and conifers such as redwood and cedar are rarely infested. These or other resistant species should be considered when planting in infested areas, or when replacing infested trees. Avoid trees like Modesto ash, known to be especially susceptible to mistletoe infestation. Where many new trees are being planted, control mistletoe in any surrounding infected trees to reduce the infection of new trees.