Archive:Poplar/Leaf Bronzing of Aspen
From Bugwoodwiki
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From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.
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Importance
These systemic pathogens cause degenerative diseases that can result in diebacks, declines, and reductions in growth and yield potential.
Look For:
General:
• Vein necrosis, chlorotic spots, chlorotic line patterns, mosaic patterns, variegation, mottling, and abnormal leaf shape, curling, and puckering.
• Excessive branching (brooms). Symptoms differ, depending on casual agent, poplar species, age of tree, season, and host condition. Trees can also be infected but not show any symptoms. Leaf bronzing of aspen:
• Leaves yellow in late July and August, then turn bronze and finally dark brown. Leaf petioles on affected branches remain yellow, and there is often a brown discoloration in the wood of the branches.
Leaf bronzing of aspen:
• Leaves yellow in late July and August, then turn bronze and finally dark brown. Leaf petioles on affected branches remain yellow, and there is often a brown discoloration in the wood of the branches.
Biology
These pathogens have not been extensively studied in poplars. Additional research is needed to develop reliable methods for detecting and identifying the viruses in poplars. Once infected, a tree will remain infected throughout its life. Viruses can be spread by insect and nematode vectors or by vegetatively propagated planting stock.
 Photo by USDA Forest Service - North Central Research Station Archive, USDA Forest Service, Bugwood.org |
Monitoring
Suspect a virus or other systemic pathogen when you can't find the cause of a tree's declining vigor. Systemic pathogens should not be a serious problem in trees grown on short rotations except when the stumps and root systems decline in vigor, reducing coppice reproduction.
Control
• Plant only vigorous, disease-free stock. Cuttings should not be taken from trees obviously stressed or exhibiting symptoms of virus infection.
• Aseptic culture techniques and heat treatments are available to free poplar clones from know virus infections. These treatments will not guard against virus infections after planting, but will reduce impact on trees grown on short rotations.
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| Leaf Puckering |
At this time there are few direct control measures because we don't fully understand what systemic pathogens are important and we can't detect and identify them efficiently.
For Additional Information:
Berbee, J. G.; Omuemu, J. O.; Martin, R. R.; Castello, J.D. 1976. Detection and elimination of viruses in poplars. In: Intensive plantations culture: Five years research. Gen. Tech. Rep. NC-21. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station: 85-91.
Martin, R. R.; Berbee, J. G.; Omuemu, J. O. 1982. Isolation of a potyvirus from declining clones of Populus. Phytopathology. 72: 1158-1162.
Navratii, S. 1979. Virus and virus-like diseases of poplar: are they threatening diseases? Report 19: Poplar research, management, and utilization in Canada. For. Res. Inf. Pap. 102. Ottawa: Ontario Ministry of Natural Resources; 19: 1-17.
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| Virus-infected leaves. |
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| Virus-infected leaves. |
