Carlson, Clinton E.; Gilligan, Carma J. Histological differentiate 

 among abiotic causes of conifer needle necrosis. Res. Pap. 

 INT-298. Ogden, UT: U.S. Department of Agriculture, Forest 

 ice, Intermountain Forest and Range Experiment Station; 1980. 



1022967147 



' P- 



Symptoms induced by phytotoxic gases within conifer needles 

 can be differentiated histologically from those caused by other abiotic 

 agents including winter drying, drought, and salt. However, it is not 

 possible to differentiate among symptoms caused by hydrogen 

 fluoride, sulfur dioxide, ethyl mercaptan, and hydrogen sulfide. 

 Phytotoxic gases cause hypertrophy and hyperplasia of vascular 

 parenchyma, endodermis collapse, and intense vascular staining. The 

 other abiotic agents induce mesophyll collapse with little or no obser- 

 vable effects on vascular tissues. Histological analyses should be 

 useful in diagnosis of air pollution-induced injury and damage in con- 

 iferous forests. 



KEYWORDS: phytotoxic gases, winter injury, conifer needles, symp- 

 toms, histology, air pollution, diagnosis, needie necrosis 



The Intermountain Station, headquartered in Ogden, Utah, is one 

 of eight regional experiment stations charged with providing scientific 

 knowledge to help resource managers meet human needs and protect 

 forest and range ecosystems. 



The Intermountain Station includes the States of Montana, Idaho, 

 Utah, Nevada, and western Wyoming. About 231 million acres, or 85 

 percent, of the land area in the Station territory are classified as 

 forest and rangeland. These lands include grasslands, deserts, 

 shrublands, alpine areas, and well-stocked forests. They supply fiber 

 for forest industries; minerals for energy and industrial development; 

 and water for domestic and industrial consumption. They also provide 

 recreation opportunities for millions of visitors each year. 



Field programs and research work units of the Station are main- 

 tained in: 



Boise, Idaho 



Bozeman, Montana (in cooperation with Montana State Univer- 

 sity) 



Logan, Utah (in cooperation with Utah State University) 



Missoula, Montana (in cooperation with the University of 

 Montana) 



Moscow, idaho (in cooperation with the University of Idaho) 

 Provo, Utah (in cooperation with Brigham Young University) 

 Reno, Nevada (in cooperation with the University of Nevada) 



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•fr U.S. GOVERNMENT PRINTING OFFICE: 1983-0-673-03< 



