1917] DISEASES OF PLANTS. 51 



is considered to Influence the amount of infection, the largest proportion of 

 diseased plants occurring on coarse, sandy soils. 



Black rot of tobacco, K. Pkeisseckeb (Fachl. Mitt. Osterr. Tabakregie, 15 

 {1915), No. 4, pp. 113-116, figs. 4). — This is a brief discussion of the disease 

 attacking stored tobacco due to Sterigmatocgstis nigra (Aspergillus niger). 

 The accounts given by Rapaics (E. S. R., 30, p. 450) and others are referred to. 



Suggestions for the control of the more serious plant diseases occurring 

 at Hood River, L. Childs {Oregon Sta. Bui. 141 {1911), pp. 28-32 ) .—Based 

 upon experiments carried on in this region, directions are given for the spraying 

 of apple, pear, and peach trees for the control of the more important diseases 

 to which they are subject. 



Diseases of the apple, pear, and quince, C. R. Okton {Proc. State Hort. 

 Assoc. Penn., 51 {1916), pp. 45-52, pis. 4). — The author has limited the discus- 

 sion in this paper to diseases of orchard fruits not treated in the communica- 

 tion previously noted (E. S. R., 35, p. 351). The several diseases are dealt with 

 alphabetically in connection with their hosts. 



The oak fungus disease of fruit trees, W. T. Hobne {Proc. Fruit Growers' 

 Conv. Cal.. 4I {1915), pp. 208-215). — This includes a report on experiences with, 

 also a discussion of, the oak fungus and wood decay of fruit trees. 



It is stated that English walnut budded about a foot above tlie ground on 

 California black walnut is safe from the oak fungus. Isolation trenches, if 

 kept open and disinfected, are successful in checking the spread of the infec- 

 tion by m.eans of rhizomorphs. The fungus goes down several feet. The effects 

 of carbon bisulphid in the soil are variously reported, depending apparently on 

 soil conditions. 



Wood decay of fruit trees appears to be more widely destructive in this 

 region than the oak fungus, as it affects wild growths abundantly. Unlike the 

 oak fungus, it can not enter except through a break made in the bark. The 

 fruiting bodies, after being dry all the summer, may give off infecting spores 

 within 24 hours after being moistened. The fungus works in the wood chiefly 

 or exclusively. Wounds should be painted before being wet, and they should 

 be kept covered with paint or other reliable disinfectants, among which cor- 

 rosive sublimate is considered to be one of the best. It is thought that apples 

 and walnuts, carefully protected from disease, may live 100 years. 



Observations on the relation of the height of fruit to apple scab infection, 

 L. Childs {Oregon Sta. Bui. 141 {1917), pp. 5-11, figs. 6).— While engaged in 

 some experiments on apple scab, the author observed that the fruits near the 

 top of the trees were usually much more scabby than those produced nearer 

 the ground. In following up this observation, several orchards were examined 

 as to the actual conditions existing at harvest in certain trees that had 

 been carefully sprayed. 



It was found that at least one-fourth of the crop in case of most of the 

 trees was produced at a height of 15 ft. or more, and at least one-half of 

 this amount was found to be scabby, while lower and poorer quality fruit 

 possessed a very slight scab infection. On smaller trees sprayed in exactly 

 the same manner as the above, much better results were obtained. Under 

 the conditions prevailing in the Hood River region during the spraying season, 

 the average wind velocity is said to be too great for good spraying at a height 

 of more than 22 or 23 ft. On this account, it is recommended that a tower 

 be used in .spraying and that long, out-of-the-way limbs be cut back. 



Blister canker control, H. E. Vasey {Nebr. Hort., 6 {1916), No. 1, pp. IS).— 

 Stating that apple blister canker is to be found in fully 96 or 97 per cent 

 of the orchards in Nebraska, the author discusses practical means of control. 

 These include acquaintance with the disease, skillful scraping and pruning 



