- Author: Robert J Keiffer
Most of us are familiar with the mistletoe plant ... at the very least from Holiday time Christmas carols and sprigs of it sold for Christmas Holiday decorations. Here in Mendocino County, the most common mistletoe plant recognized during those times is the Oak Mistletoe or Pacific Mistletoe (Phoradendron villosum (Nutt.). This parasitic shrub is native to California and the western U.S. where it grows mainly upon Blue oak and Valley oak.
Recently, within the last few months, casual observation at the UC Hopland Research & Extension Center appears to show a high mortality of these unique plants. Being a parasitic plant that grows on the trunks and limbs of oak trees, it grows its root-like "haustoria" into the water-conducting transport system of the tree, where the haustoria also infiltrates between the cells to absorb (and rob) nutrients of the host tree.
Based upon circumstantial evidence and the co-timeliness with the severe drought conditions an assumption can be made that the mistletoe mortality is drought-related. Perhaps the nutrient and water flow of the host tree is so stressed during drought years that the parasitic action by the mistletoe plant is compromised.