PARCH BLIGHT ON DOUGLAS FIR 47 



which are used to the humid insular chmate of the region west of 

 the Cascades, at a time of year when their physiological functions 

 are least active and they are least able to withstand this parching. 

 It is apparent that the injury is more severe in the vicinity of 

 Portland because this region is particularly exposed to the direct 

 sweep of the east winds down the canyon of the Columbia River. 

 The injury has, however, been reported from a number of other 

 points in Western Oregon and Washington, where the dry winds 

 from the interior have evidently been active. 



The Douglas fir of the region west of the Cascades is called the 

 Coast form, and it is particularly dependent upon a humid mild 

 climate. The Douglas fir east of the Cascades in Oregon re- 

 sembles the Rocky Mountain form, and it endures a much drier 

 and severer climate. It is interesting, therefore, to note that in 

 passing up the Columbia River evidences of the injury disappear 

 at about 35 miles eastward from Portland at a point about oppo- 

 site the crest of the Cascades, where the Douglas fir takes on the 

 hardier characteristics of the Rocky Mountain form. 



Usually the affected trees show no permanent ill effects from 

 this parching, though undoubtedly the loss of part of their 

 foliage inhibits their growth. In particularly exposed spots, 

 such as at Crown Point on the Columbia Highway, the old 

 trees have very narrow spire-shaped crowns, due, no doubt, to 

 the annual parching of their tender twigs by these dry winds. 

 Often their foliage is largely on the western side, but yet the crown 

 has not the shape of the typical wind-swept seaside tree. 



This form of injury is analogous to the "Winter Injury of the 

 White Pine in 1908" in Maine, described by Mr. W. J. Morse 

 in Bulletin 164 of the Maine Agricultural Experiment Station. 

 It also has much in common with the so-called (and I might add 

 unfortunately named) "red-belt disease," which is a not infre- 

 quent cHmatic blight of the timber fronting on the desert in an 

 arid country. ^ I suggest "parch blight" as an expressive and 

 distinguishing name for this injury. 



^Hedgecock, G. G., Winter-killing and smelter-injury in the forests of 

 Montana. Torreya, vol. 12, no. 2. 



