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Gardening tips on pruning bougainvilleas

Author: Cathy Cromell
Issue: January, 2013, Page 131



Q&A - ASK THE EXPERTS

Q - My Aleppo pine tree has many brown needles on several branches. What’s happening?

A - This non-native pine (Pinus halepensis) may be suffering from Aleppo pine blight, which to date has no known cause, notes Dr. Mary Olsen, Plant Pathologist, University of Arizona. Symptoms often appear in late fall as brown tips on branches. Sometimes large parts of branches have dead needles, and a few branches, or much of the tree, may be afflicted. Most trees recover with effective irrigation through the winter by applying water at and slightly beyond the canopy edge, soaking 3 feet deep with each irrigation.

Aleppo pine wilt is a less likely possibility. It is caused by a nematode that infests the heartwood of trees. According to Dr. Michael A. McClure, University of Arizona School of Plant Sciences, trees infected with pine wilt disease die systemically with the entire tree wilting and then turning brown in three to four weeks. Brown needles remain on the tree.

Pine wilt disease can be distinguished from pine blight by the pattern of spread and speed of death. Once a tree becomes infected with pine wilt and symptoms appear, there is nothing that can be done to stop the disease. Dead trees should be removed. View photos of Aleppo pine blight and pine wilt at ag.arizona.edu/plp/plpext/diseases/trees/pine/aleppopinemain.html.

If you suspect your tree has died from pine wilt disease, seal several 3"-long samples from the heartwood (not the bark layer) in a sealable plastic bag and send to: Michael A. McClure, School of Plant Sciences, 303 Forbes Bldg., University of Arizona, Tucson, AZ, 85721. A diagnosis will be provided by e-mail.
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