White ash is susceptible to a variety of natural and man-made pathogens.
Ash decline (also called ash dieback or ash yellows) has increased over
the last 40 years and is especially prevalent in New York, Pennsylvania,
and Vermont. Mortality rates are as high as 90 percent in some areas of
New York. Nearly all of the ash decline from 1980 to 1986 occurred in
areas with high levels of atmospheric deposition of sulfur (S0x) and
nitrous (NOx) oxides. Although there is no concrete evidence that acid
deposition is the causal agent, it can not be dismissed . Ash
decline probably results from multiple factors--the disease, ash
yellows, caused by a mycoplasmalike organism; canker fungi (Fusicoccum
spp.); viruses; acid deposition; and drought . Maintaining good
tree vigor is the primary control recommendation. Preventative measures
that seem to abate ash decline include : watering, fertilizing,
applying fungicide, covering wounds with a fungicide-augmented dressing,
and avoiding planting white ash in areas of high acid deposition.
White ash has been found to be sensitive to ozone (O3), sulfur dioxide
(SO2), and acid deposition. Chappelka and others  found that total
biomass was reduced 14 percent after exposure to these atmospheric
contaminants. Visible evidence is characterized by initial purple-white
stippling on the adaxial leaf surface which turns into necrotic lesions.
This occurred on 66 percent of the plants.
White ash varies in cold hardiness with the latitude of origin. Trees
grown in the North have a lower lethal temperatures than those from the
South. When revegetating an area, seed and seedlings must be procured
from a source that is climatically and geographically similar [1,13].
Clark and Schroeder  have developed equations to calculate the green
volume, green weight, and dry weight of white ash.
- 1. Alexander, Nancy L.; Flint, Harrison L.; Hammer, P. Allen. 1984. Variation in cold-hardiness of Fraxinus americana stem tissue according to geographic origin. Ecology. 65(4): 1087-1092. 
- 3. Chappelka, A. H.; Chevone, B. I.; Burk, T. E. 1988. Growth response of green and white ash seedlings to ozone, sulfur dioxide, and simulated acid rain. Forest Science. 34(4): 1016-1029. 
- 4. Clark, Alexander, III; Schroeder, James G. 1986. Weight, volume, and physical properties of major hardwood species in the southern Appalachian Mountains. Res. Pap. SE-253. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Experiment Station. 63 p. 
- 13. Goldsmith, F. B.; Boudreau, P. 1979. Height growth and apical damage of white ash (Fraxinus americana L.) from various latitudes outplanted in New Brunswick. Canadian Journal of Forest Research. 9: 27-30. 
- 16. Hibben, Craig R.; Silverborg, Savel B;. 1978. Severity and causes of ash dieback. Journal of Arboriculture. 4(12): 274-279. 
- 23. Millers, Imants; Shriner, David S.; Rizzo, David. 1989. History of hardwood decline in the eastern United States. Gen. Tech. Rep. NE-126. Bromall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 75 p. 
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