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Updated: August 8, 2017
During March through May, yellow spots form on the previous year's needles. These enlarge and become reddish-brown patches on an otherwise green needle. These needles then fall.
Rhabdocline pseudotsugae and R. weirii
Place plants in locations where good air circulation is available. Maintain good weed control so that air circulation is not impeded. When approximately 10 percent of the buds have broken in the spring, apply a fungicide. Repeat the application 1 week later and again 3 weeks after bud break. If spring is cold and new shoots mature slowly, apply a fourth spray 2 to 3 weeks after the third spray.
From March through June, the previous year's needles gradually brown and fall. Rows of tiny, black fungal fruiting structures line the midrib on the underside of the needles. A magnifying glass is needed to see individual structures.
Place plants in locations where good air circulation is available. Maintain good weed control so that air circulation is not impeded. When new shoots are 1½ inches long, apply a fungicide. Repeat the application 3 weeks later.
Twig tips curl downward, turn dark brown, and die. Small black fungal fruiting structures dot the dead tissue.
Prune and destroy blighted tips.
Rhabdocline needlecast symptoms and signs.
Rhabdocline fruiting structures.
Swiss needlecast fruiting structures
Diplodia twig blight. Note black fungal structures on the curved part of this tip.
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