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Tip Blight of Pine May Cause Death of Shoots in Spring
submitted by Sarah Browning, UNL Extension Educator
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 fungal disease 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.
In 2009 and 2010, long periods of wet spring weather created ideal conditions for Sphaeropsis infections. Branches in the tree’s lower canopy are often more severely infected due to higher humidity levels, but any part of the tree can be affected. The most conspicuous symptoms of Sphaeropsis tip blight are new shoots that are quickly killed before they fully expand and have short, brown needles still partially encased in their sheath. 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 may 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. Extremely wet spring weather promotes the development of this disease. Fungal spores are dispersed primarily on rain splash. High humidity also promotes the germination of spores.
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. It may also be mistaken for pine wilt, but dead branches will have stunted, dead shoots at the tips of branches and the entire tree will not be affected.
New shoots are most susceptible during a two-week period beginning at bud break and continuing through mid-June. In eastern Nebraska, two applications of fungicide are recommended for control during this period. The first application should be 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.
Several fungicides are effective in treating this disease, including Thiophanate methyl (Cleary’s 3336, Fungo), or Bordeaux mixture. Read and follow all label directions carefully before application.
For more information and specific chemical recommendations, refer to NebGuide 1845 “Sphaeropsis Tip Blight of Pine”, http://www.ianrpubs.unl.edu/sendIt/g1845.pdf.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office
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