Every effort should be made to maintain plants in a high state of vigor. Because drought stress is thought to be one of the main factors that predisposes plants to disease, it is especially important to water plants deeply and regularly during drought. Do not replant infested areas to English boxwood. Both American boxwood and several cultivars of Buxus microphylla, tested under field conditions, have been observed to be resistant to decline in field tests and can be planted in areas where English boxwood decline has been diagnosed. No fungicides have been found to be effective in controlling this disease.
Damage to roots of both American and English boxwoods can occur from the feeding of several types of plant parasitic nematodes. The most common nematodes that feed on boxwood roots in Virginia are ring, lesion and spiral nematodes. These nematodes obtain nutrients by inserting their syringe-like mouthparts into root cells and removing the contents.
When populations of any of these nematodes are high in soil, their feeding can cause severe damage to roots and may also predispose roots to infection by fungi. Symptoms on roots include stunting and browning. Aboveground symptoms resemble those caused by root rot fungi: The plant undergoes a gradual decline characterized by yellowing and bronzing of the leaves and dieback of large sections of the plant.
According to the University of Massachusetts-Amherst Center for Agriculture, a boxwood blight (Cylindrocladium pseudonaviculatum) was found in Massachusetts and is found mostly in English boxwood. Other extension services, in Connecticut and in other states, are also reporting on the blight.
At Purdue University, scientists explained that this blight was first observed in the United Kingdom in the mid-1990s, moved to New Zealand in 1998, and is endemic to Central America, the Caribbean and Mexico. The blight recently was found in the northwest region of North Carolina. The worry is that asymptomatic plants will be shipped to other uninfected regions, spreading the blight.
The best management strategy at this point, before more is known about the pathogen, is to not introduce any boxwoods from unverified sources, either into the nursery or landscape.
Identifying another mystery
Jim in Braxton County has a thought about the last mystery plant.
"Just a guess, but this may be a [crop failure] of a kind of celosia. Had one a few years back. Sometimes the seed company will go ahead and use them to help fill the seed pack."
Reach Sara Busse at sara.bu...@wvgazette.com or 304-343-3909.