1032 DISEASES NOT DUK TO PARASITES, OK OV UXKNOWN ORIGIN 



painting the wound with a protective material. The Philippine Bureau 

 of Agriculture has worked satisfactorily along the above lines, obtaining 

 improvement which leaves little to be desired under this treatment. 



803 - " Parch Blight " on Douglas Fir in Oregon. — munger Thornton t. in The Plant 



Wii)l(i,ViA. HI, No. J, ])]). 4')-|7. I'.altiiiKirc-, Md. February i<)i(). 



Quite frequently, in the spring of the year, the foliage of the Douglas 

 fir trees in the vicinity of Portland, Oregon, turns brown, and entire trees 

 are sometimes as sere as though recently dead or dying. With the begin- 

 ning of the growing season, however, most of the buds open normally, 

 and by midsummer the trees have regained their usual green appearance, 

 many of the old needles dropping off. 



The injury is generally limited to temporary inhibition of growth, with 

 a slight loss of timber production. Isolated trees are more liable generally 

 to the disease than dense groves. P^xposed eastern sides of forest are more af- 

 fected than the western sides in protected locations. 



The blight is due to the dry east winds that occasionally sweep across 

 the Cascade Moimtains, the vicinity of Portland being particularly exposed 

 to the direct sweep of these winds down the canyon of the Columbia river. 



The Douglas fir [Pseudotsuga Douglasii) in this region is called the Coast 

 form, and is particularly dependent upon a humid, mild climate, and conse- 

 quently suffers from, these hot, dry blasts, which cause excessive transpira- 

 tion and produce the above injuries. 



806 - Fruit Injury during the Fumigation of Citrus Trees: Causes and Remedies (i). -- 



\AoGLtrM R. S. in The Fruit World of Australasia, Vol. XVII, No. 3, pp. 70-72. Mellxnirr^-, 

 March ist, 1916. / 



The production of citrus fruits in Australia amounted in 1913-1914 to 

 1,341,878 bushels of oranges of the value of £ 497,286, while that of ler/lons 

 was 297,083 bushels valued at £ 97, 753. The problem of protecting xiitrus 

 trees against their enemies therefore is of great importance. The r/iethod 

 of control most in use is that of fumigation with hydrocyanic acid, a very 

 effective system, but one which sometimes pits the fruits. The writer 

 proposed to investigate methods of avoiding such injury. The pitting of 

 fruit caused by hydrocyanic acid fumigation has been put down by spec- 

 ialists to various causes, such as sulphuric acid, the presence of nitric acid 

 in the sulphuric acid, the too rapid evolution of the gas. the absorption of 

 the gas by the water on the tree, an abrasion of the fruit produced by the 

 tent placed over the tree, etc. The impurities contained in the two re- 

 agents used, however, potassium cyanide and sulphuric acid, are in such small 

 quantities that they cannot produce an}- marked elTect. On the other hand 

 there can be no question of the pitting being caused by minute drops of 

 sulphuric acid thrown off in the over-rapid evolution of the hydrocyanic 

 acid, as in that case the injur}'- would only affect the fruits placed lowest 

 and in the immediate vicinity of the generator. The most seriously injured 

 fruits, however, are those at the top, and sometimes they are the only ones 



(i) Sec also B. June i';ii. No. kKv. (/'-'/■) 



