Mistletoe Control: Understanding Ethephon Treatment and Limitations

Mistletoe is a hemiparasitic plant that extracts water and nutrients from host trees via root-like structures called haustoria. While it rarely kills mature trees, heavy infestations can weaken them.

Chemical Control with Ethephon

Ethephon (a plant growth regulator) is labeled for mistletoe control but must be sprayed directly on the mistletoe foliage—not applied to soil. Complete coverage of the parasitic plant is necessary, which is often impractical for high infestations in large trees.

Practical Considerations

• Birds spread seeds via droppings; new infections occur regularly.
• Pruning infected branches is effective only if the haustoria are fully removed.
• For light infestations in large trees, monitoring may be the most realistic approach.

Since mistletoe provides wildlife habitat and rarely causes severe harm, many arborists recommend tolerance over aggressive control.