Sphaeropsis Tip Blight
Browning and death of branch tips is quite common in older, well-established pine plantings. Such damage is often due to Sphaeropsis Tip Blight, (syn. Diplodia tip blight). Infection kills current-year shoots and eventually may kill whole branches or the entire tree. This causal fungus becomes increasingly more common and destructive as trees age, although young trees can be affected. Austrian pine is the most severely affected of the pines, but Ponderosa pine, Scotch pine and Mugo pine are also susceptible.
The most conspicuous symptoms of Sphaeropsis tip blight are stunted new shoots with short, brown needles still partially encased in their sheath. Infected shoots are quickly killed and may be located throughout the entire tree, although damage is generally first evident in the lower branches. The severity of damage may vary considerably throughout the tree, with some branches that have been infected several years in a row dying back completely. After two or three successive years of infection, treetops may also be extensively damaged. Repeated infections reduce growth, deform trees and ultimately kill them.
Small, black, pimple-like structures develop at the base of infected needles and on the backside of pine cone scales. These structures produce additional fungal spores that can re-infect the tree.
Sphaeropsis tip blight can be confused with damage caused by pine tip moths; however, pine tip moth damage can be distinguished by the presence of larvae or tunnels within the affected shoot.
Extremely wet spring weather promotes the development of this disease. Fungus spores are dispersed primarily on rain splash from March to October. High humidity also promotes the germination of spores.
New shoots are most susceptible during a two-week period starting when the buds begin to open and continue to be susceptible through mid-June. Two applications of fungicide applied during this period are recommended. In eastern Nebraska, an application made during the third week in April and a second application in the first week of May provides optimum control.
Applications made after mid May are ineffective. Bordeaux mixture, liquid copper (Tenn-Cop 5E) or fixed copper (Basic copper sulfate, Tribasic copper sulfate) are effective in treating this disease.
Read and follow all label directions carefully before application.
Sphaeropsis Tip Blight of Pine, University of Nebraska- Lincoln Extension