Brown Patches on False Yew

By Susan Camp

One of my workout buddies from Williamsburg mentioned last week that she has a low border hedge of evergreens called false yew. Some of the individual shrubs have developed brown patches, and part of the hedge is becoming unsightly. She wanted to know what she can do to stop the patches from progressing.

Master Gardeners always want to help other gardeners with their plant, soil, or pest problems, but sometimes we just don’t know where to start. I wasn’t familiar with the name “false yew,” but I knew from my friend’s description that these shrubs must be very yew-like in appearance. After several Google attempts, I concluded that she was referring to Cephalotaxus harringtonii var. drupacea, commonly known as Japanese plum yew.

A Japanese native, drupacea makes a good substitute for English yew (Taxus baccata) in Southern gardens. Unlike English yew, drupacea is heat and drought tolerant, and thus able to survive hot summer weather. It grows best in USDA Hardiness Zones 6 to 9.

Similar in appearance to English yew, drupacea displays glossy, dark green yew-like leaves and gray bark that exfoliates in strips as the shrub matures. New spring foliage is pale lime green.

Drupacea is dioecious, which means that male and female reproductive organs are found on separate trees. Male trees bear cream-colored to brown flowers beneath each pair of leaves and release pollen from March to May. Female flowers develop into fleshy plum or olive-like fruits that darken from pale green to brown. The fruits reportedly are edible, although caution should be taken to definitively identify the shrub as drupacea, as English and other yew fruits contain toxic substances.

Drupacea prefers moist well-drained, sandy soil with a pH of 5 to 7. It tolerates full sun in cooler climates, but needs shade where summers are hot. Drupacea doesn’t like wet feet, and soggy clay soils will lead to yellowing of the foliage and eventual root rot. Nitrogen deficiency causes yellowing of the lower half of the shrub, particularly in alkaline soils. Magnesium deficiency causes yellowing of the edges of older leaves.

Few insect pests attack drupacea, although large infestation of black vine weevils, mealybugs, or scale insects can lead to yellowish-brown discoloration of the leaves.

Several sources mentioned that Phytophthora and Armillaria fungi will infect drupacea, stunting and possibly killing the shrubs.

Phytophthora survives in soil that remains wet for a long period, causing root and crown rot. The fungus spreads by irrigation, runoff, and splashing rain and can live in the soil for years, leading to wilting of foliage and color change. The bark at the soil line darkens and red-brown discoloration is revealed when the bark is stripped away.

Cultural strategies include improving drainage by aerating and amending compacted soil; planting shrubs on mounds; and pulling soil away from the crown. To help prevent infection, plant resistant trees and shrubs

Armillaria mellea causes root rot in evergreen and deciduous ornamental shrubs and trees. The symptoms include sparse, stunted, yellow leaves and reduced height. If the roots are exposed, black, root-like strings attached to the shrubs roots and white mats of fungus are visible between the bark and wood. The defining characteristic of Armillaria is the presence of honey-colored mushrooms at the soil line. Shrubs and trees younger than 15 to 20 years are more likely to be killed than older trees.

No effective chemical controls have been developed to combat Armillaria. If a shrub or tree is killed by the fungus, remove and destroy the stump and debris. To help prevent Armillaria infection, plant resistant trees and shrubs.

This leads us back to my friend. I still don’t know if her shrubs are drupacea, or if they have a fungal infection. My recommendation to her was to contact Williamsburg-James City Master Gardeners or Tree Stewards and schedule a home visit. If you have a question, you can contact a Gloucester Master Gardener or Tree Steward by calling the Gloucester Extension Office at (804) 693-2602.

June 6, 2019