May 2007 Forest Health Protection and State Forestry Organizations

15.9 WEB Feb 2010 Management Guide for

By Robert James Needle Blight US Forest Service Dothistroma septosporum (Dorog.) Morelet. = Dosthistroma pini Hulb. = Sexual stage [teleomorph]: Scirrhia pini Funk & A.K. Parker

Primary Ponderosa ; Hosts: Lodgepole Pine Recent unprecedented high levels of this disease have been found in lodgepole pine in British Columbia, Canada and Minor Host: Western White ponderosa pine in central Pine Montana.

Topics Damage 1 Introduction Life History 2 The major impact of Dothistroma may be predisposed to attack by bark Management 2 needle blight is growth reduction beetles. which may result from excessive The most serious disease often Other Reading 3 defoliation. Tree mortality is rare, occurs near rivers, especially in Field Guide although severely-infected young canyons where high humidity occurs trees may be killed during years for prolonged periods. Damage is Management Guide Index when environmental conditions are most noticeable in the early spring conducive to infection and buildup before new foliage is produced. of the pathogen. Large-diameter trees with severe foliage infection Key Points  Growth is adversely affected but infected trees are MANAGEMENT OVERVIEW seldom killed.  High rainfall and 1. Damage potential rarely warrants control efforts. In prolonged periods most situations, Dothistroma infection will result in little of humidity are growth loss or mortality. conducive to 2. Recognize hazardous sites. Sites that are prone to infection and prolonged periods of high humidity provide ample disease severity opportunity for sporulation and infection.  Recent epidemics 3. Thin favoring resistant trees or . Individual may be related to resistance to needle blight often varies considerably within climate change a species on a site providing opportunities to remove the that has altered most damaged trees during routine thinnings. Non- traditional rainfall susceptible species may also be selected for retention. patterns.

Back to menu Page 2 Dothistroma Needle Blight 15.9 Life History

Infected needles produce spores that are disseminated primarily via rain splash onto uninfected foliage. Infection occurs on previous years’ needles during the spring when weather conditions (rain and high humidity) are conducive; some current year needles may be infected during mid summer. Black, erumpent fruiting bodies of Dothistroma needle blight The pathogen requires two growing seasons to complete its life cycle. Infected needles characteristically Dothistroma needle blight of have reddish-brown bands that often Ponderosa pine results in a needle contain black fruiting bodies. The discoloration and loss of two-year base of infected needles often old foliage. With repeated remains green; they often turn yellow infections, trees may have no foliage to brown and drop prematurely. older than two years.

Distinctive banding pattern of Dothistroma Unusually severe needle blight infections

Trees that are off-site may be particularly susceptible Management to infection. Some sites This disease can be managed by may be related to climate change, are especially favorable favoring less-susceptible species in particularly increased summer for the fungus, for areas of high disease potential. precipitation, that is has traditionally example river canyons However, since tree mortality is been rare. Situations such as these where moisture lingers in usually rare, little is often done to could eventually alter the traditional the air after rain and the manage Dothistroma needle blight in hands-off approach to managing the western shores of the inland Northwest. disease. Flat he ad La ke i n Montana. There is even Recent unprecedented high levels of some evidence that this disease have been found in climate changes have lodgepole pine in British Columbia, favored the fungus by Canada and ponderosa pine in increasing summer central Montana. These outbreaks precipitation. Under each of these conditions, infection can be chronically severe, leading to tree death. 15.9 Back to menu Dothistroma Needle Blight Page 3

Other reading Forest Health Hagle, S. K., K. E. Gibson, S. Tunnock. 2003. Field guide to diseases and Protection and insect pests of northern and central Rocky Mountain . State Forestry U.S.D.A. Forest Service, Northern and Intermountain Regions, Rept. Organizations No. R1-03-08. 197 pp. James, R.L. 1981. Red band needle blight of pine on the Clearwater National Forest, Idaho. USDA Forest Service, Northern Region., Forest Assistance on State Pest Management. Report 81-21. And Private Lands

Montana: (406) 542-4300 Peterson, G.W. 1982. Dothistroma needle blight of . USDA Forest Service, Forest Insect and Disease Leaflet 143. Idaho: (208) 769-1525

Woods, A., K.D. Coates and A. Hamann. 2005. Is an unprecedented Utah: (801) 538-5530

Dothistroma needle blight epidemic related to climate change? Nevada: (775) 684-2500 BioScience 55(9):761-769. Wyoming: (307) 777-5659

Assistance on Federal Lands

US Forest Service Region One Missoula: (406) 329-3605 Coeur d’Alene: (208) 765-7342

US Forest Service Region Four Ogden: (801) 476-9720 Boise: (208) 373-4227

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