Sphaeropsis kills trees by killing the new foliage year after year or by initiating girdling stem cankers on stressed or injured trees. Shoot blight is common on trees of all ages, but cankers are more prevalent in saplings and pole-sized trees than in large trees. All symptoms are generally characterized by conspicuous amounts of resin. Peak spore production and infection usually coincide with host bud break and shoot and needle elongation. Spores from current-year infections may be disseminated in the same year or the following year.
Infection can also occur through wounds caused by various agents such as hail and insect feeding.
The fungus invades woody tissue under such conditions. 28 Management Guidelines Prevention is the best way to control Sphaeropsis. Avoid planting red pine in areas where Sphaeropsis has been a problem. Do not plant red pine on poor sites, particularly sites subjected to periodic severe droughts. Avoid planting red pine seedlings adjacent to infected conifer windbreaks.