Sphaeropsis Tip Blight of Pines
Shoot blight on Austrian pine
Sphaeropsis is a common problem associated with pines. A fungus that causes shoot blight and cankers on pines in plantations, windbreaks, and ornamental plantings. The most common hosts are Scotch pine and Austrian pine. Sphaeropsis usually attacks trees stressed by one or more of the following factors: poor site, drought, snow damage, mechanical wounds, and insect damage.
Sphaeropsis can kill a pine tree over a period of several years by continuing to kill off each season's new growth.
Disease Cycle and Symptoms
Sphaeropsis overwinters in shoots, bark, cones, or litter. Spores are disseminated during early spring to early summer. This is normally the wettest time of the year and the spores are spread throughout the tree as the rain splashes on them. The spores can also be translocated from tree to tree by wind. The fungus invades and kills shoot tissue and forms spores on dead tissue.
Shoot blight and branch/stem cankers are the most common symptoms of Sphaeropsis. Shoot blight is common on trees of all ages, but cankers are more prevalent in saplings and pole-size trees. All symptoms are generally characterized by larger than normal amounts of resin.
Shoot Blight: Infected shoots are straw-colored, fail to develop fully, and curl over like a shepherd's crook. They are soaked in resin and become very brittle over time as the resin dries. Black fruiting bodies may be found on dead needles or shoot tissue.
Cankers: Look for elongated, depressed areas on branches of stems, often with resin flow on outer bark. Cankers start from shoot infections or through wounds on the branches or stem. When bark is removed, gray to black staining and brown pitch-soaked wood are visible. Older infections may have a pronounced callus growth around canker edges. The branch or stem above a girdling canker will be killed.
Control
Prevention is the best way to control Sphaeropsis tip blight. Avoid planting highly susceptible exotic pines where Sphaeropsis has been a problem. All pines are more susceptible to disease when planted on poor sites or when subjected to other stresses. Wounding should be avoided during peak periods of spore dispersal. Remove and dispose of any infected tips, needles, and cones. Keeping pines as healthy as possible is the first step in defense. Keep them well watered during dry periods, including the winter season.
A three-step fungicide treatment can control this disease and protect pine trees.
See your RYANPro to learn more about preventing this serious disease on your pines.