Needle Blight Tree Disease - Prevention and Control

This group of blight diseases including Diplodia, Dothistroma and brown spot, attack conifers by girdling needles and killing branch tips. Blights are insidious diseases and cause major commercial and ornamental damage to conifers in North America. Infected needles often fall from the tree, creating a denuded look. Blight can result in dramatic browning of the foliage, beginning on the lower branches. Although the tree might not die you may wish it be removed.

Prevention:

Repeated annual cycles of infection can result in dead limbs and eventual loss of any meaningful ornamental or commercial value. Breaking this infection cycle has to happen to effectively stop the fungus. Brown spot needle blight in longleaf is controlled using fire. Resistant forms of some trees are being developed for planting in endemic areas.

Control:

A fungicide spray program, repeated over several years, will eventually allow new, undamaged needles and branch tips to replace the diseased ones. Several sprayings should begin in spring where the first spray protects the previous year's needles and the second spray protects the current year's needles. When symptoms of the diseases have disappeared, you can discontinue spraying. Ask you local extension agent for recommended chemicals.