Phomopsis tip blight affects only young, succulent growth in junipers. Infection may occur from May through September and may cause the new foliage to turn reddish-brown to light gray. A few weeks later, small, black fungal fruiting bodies may be found on the base of dead foliage. Repeated infections during the growing season can cause severe twig and branch dieback, discoloration of foliage, stunting, and plant death.
Adequate control is usually accomplished by pruning and destroying infected twigs and branches during dry weather. Chemical control is usually not necessary in established plantings or in a windbreak situation. For highly susceptible junipers, a foliar application of Bordeaux mixture, other copper-based fungicides, and mancozeb can be applied to help protect new growth.
This article originally appeared in the June 18, 1999 issue, p. 80.