DISEASES OF PLANTS. 349 



treated piles which had heen in the teredo-infested waters of the Gulf of 

 Mexico for about 30 years. 



One of the piles was perfectly sound, whereas the other had been attacked, 

 particularly at the water line. No treating records were available. The 

 analyses showed that the creosote in the perfectly preserved pile originally 

 contained at least 40 per cent of naphthalene fractions, a large portion of 

 which remained in the wood. The creosote in the less perfectly preserved pile 

 contained little or no naphthalene. 



DISEASES OF PLAJSTTS. 



[Report of the botanist on plant diseases in 1910], H. T. GiJssow (Canada 

 i^Jxpt. Farms Rpts. 1911, pp. 239, 2-'i0, 2U-260, pis. //). — During the year many 

 diseases have been dealt with, among them rust of grains, mildew of wheat, 

 bitter pit, anthracnose, black rot, bitter rot, rust^ and sooty mold of apples, a 

 bacterial blight of English walnut observed at Agassiz, B. C., diseases of plums, 

 cherries, and small fruits, onion mildew, leaf spot of tomatoes, club root of 

 crucifers, also the following which are given especial notice: 



A frost injury to wheat is reported to occur on fi'osty nights on unevenly 

 ripened grain lying freshly cut. The grains shrivel, becoming lighter in 

 weight and darker in color than sound ones, and their germination is found 

 to be lower and more uneven as to time, thus perpetuating the trouble. 



A discoloration of the grains in wheat from several widely separated regions 

 is described. The embryo is darkened, and the plant seems to lack vigor. 

 Further investigations in this connection are contemplated. 



A peculiar belting of pears with a band of russet corky cells was studied, 

 and is attributed to chilling when young, these parts having been found to 

 lack the coat of fine hairs claimed to give a measure of protection when 

 present. 



A new contagious disease of peaches has been observed in the Niagara dis- 

 trict, extending into New York State. It manifests itself by cankers on trees 

 of all ages and varieties, attacking and weakening any part so that large 

 branches may be lost through breaking. The disease spreads rapidly, and has 

 quickly become very serious. 



Strawberries and raspberries are said to suffer injury during cold nights 

 when in bloom, the frost killing some of the styles and thus causing the fruit 

 to be malformed when matured. Protection by means of hedges or cheese 

 cloth and by smudge fires, also spraying with cold water in early mornings, 

 have been found useful as preventives of this injury. 



Potato scab experiments having previously led to results apparently incon- 

 sistent, a series of annual tests was entered upon to determine the relative 

 value of the treatments usually prescribed. The crops obtained by planting 

 uniformly but not badly scabbed seed potatoes showed 54.S per cent of scabby 

 tubers from the untreated seed, '54.5 per cent from the carbonate of soda treat- 

 ment (10 oz. in 10 gal. water), 53.3 per cent from the corrosive sublimate 

 (1 : 2,000), and 38.4 per cent from the formalin solution (1 lb. in 30 gal. water). 

 No conclusions are drawn. 



Internal spotting of potatoes externally sound, caused by discoloration of the 

 vascular bundles near the stem end, is reported. The trouble appears to be 

 identical with that known as " sprain " in England and as " Eisenfleckigkeit " 

 in Germany. Observers are not unanimous as to its cause. See also another 

 note (E. S. R., 21, p. 447). 



Leaf spot of elm (DothideUa ulmea) was found to extend back upon the 

 petioles to the tips of the young shoots. These twist dowuM^ard and are finally 



