Young leaves and twigs have bright-orange spots that look like paint splatters in the Spring. These spots darken and become dull orange to rust colored. Slight twig swellings are not obvious except in the Spring when their surface is orange with spores. The bark on infected twigs flakes away, growth slows, and twigs die back.
In the Summer, needles become bronzed, tan, and eventually gray. The needles of the inner and lower branches are affected first. The disease progresses upward on the shrub and outward toward the branch tips. This differs from twig blights which start at branch tips. Dark fungal fruiting structures break through the surface of infected needles. Microscopic examination of the spores reveals dark, multi-celled spores that are longer than they are wide. Affected branches thin and fall, giving the shrub an open, bare appearance.
The fungus overwinters on the plant, spores are present all year, and infection can occur whenever temperatures are mild and moisture is on the needles. Removal of the plant is better than attempting to control this disease with fungicides. However, copper hydroxide azoxystrobin, tridimefon, mancozeb, or myclobutanil can be used.
Kabatina Twig Blight
Tips of branches die and turn brown to ash gray. These remain on the shrub for many months. Larger branches can be invaded and girdled. On the dead tissue where it meets the still-living wood, small, black, pimple-like fungal fruiting structures form. Microscopic examination reveals oval, colorless spores. See Phomopsis below.
Prune and destroy infected twigs and branches. It is possible for both Kabatina and Phomopsis twig blight to occur on the same plant. If only Kabatina is present, applymancozeb. Otherwise, applymancozeb +thiophanate methylwhenever new growth is present on the shrub.