750 EXPERIMENT STATION RECORD. [Vol.41 



Spraying of twigs with wliitewasli liept tliese buds at tlie same temperature 

 as tlie atmospliere by reflecting the sun's heat. As a result, the buds swelled 

 and bloomed considerably later on these than on the unsprayed trees. In 



10 years two crops are said to have been saved by this means, although this 

 plan has not yet proved a commercial success. Other means of securing the 

 desirable late and prolonged rest include sevex'e pruning during the previous 

 VN-inter, judicious thinning of fruit, growing and turning under cowpeas, and 

 otherwise maintaining the growth until late in the season. 



The menace of silver leaf {Jour. Bd. Agr. [London'\, 25 (1918), No. 7, pp. 

 870. 871). — Reports indicate the increasing seriousness of silver leaf disease in 

 fruit trees, this trouble almost amounting to a scourge in some localities, 

 threatening with extinction some of the choicest varieties of plum, aiul 

 attacking apples somewhat less frequently. 



The only treatment found effective is early and thoroughgoing removal and 

 destruction of all affected trees or parts thereof. 



Growth of apple trees injured in the nursery by crown gall and woolly 

 aphis, W. J. ScHOENE and R. R. Reppert (Quart. Bui. Va. State Crop Pest 

 Comm., 1 (1919), No. 2, pp. 3-11, figs. 10).— In view of the indefinite state of 

 opinion, information, and practice regarding the sale, shipping, and planting 

 of nursery stock showing evidence of crown gall or woolly aphis, investigation 

 was made of these features on an orchard planted in 1914 and partly dug 

 out four years later. 



It is found that hard crown galls on or near the graft union grow as rapidly 

 as does the tree itself. Hairy root disappeared in some instances, crown-gall 

 tissue developing in the same region. Generally speaking, trees with galls 

 made less growth than did trees free from gall. Trees severely injured by 

 woolly aphis in the nursery are regarded as unfit for planting. Trees slightly 

 injured may recover and develop a satisfactory root system. 



Field experiments in spraying apple orchards for the control of apple 

 blotch, A. J. GuNDERSON (Illinois Sta. Bui. 222 (1919), pp. 551-575).— Apple 

 blotch is said to be one of the most destructive diseases of apple orchards 

 in southern Illinois. Experiments for its control were carried on during 1916, 

 1917, and 1918 to determine the relative values of Bordeaux mixture and lime 

 sulphur ; the value of different applications of these fungicides, and the effect 

 of interchanging them ; the effect of dormant applications of copper sulphate, 

 Scalecide, lime sulphur, and a combination of lime sulphur and copper sul- 

 phate ; the effect of the addition of arsenate of lead to lime sulphur ; and the 

 relative values of dusting and spraying. 



Bordeaux mixture and lime sulphur have been found practically equal for 

 the control of apple blotch. Dormant applications of the fungicides proved 

 of no value for checking the disease. Arsenate of lead appears to have the 

 same value as a spray for prevention of blotch, but the addition of this 

 material to lime sulphur did not increase the value of that spray. Dusting 

 with a mixture of finely ground sulphur and powdered arsenate of lead was 

 valueless for the control of the disease. The most important application of 

 lime sulphur or Bordeaux mixture was three weeks after the fall of the 

 petals ; and the second important application is that given five weeks after 

 their fall. Later applications were found of little value in reducing blotch 

 infection. 



An undescribed species of Ophiodothella on Reus, E. A. Bessey (Mycologia, 



11 (1919), No. 2, pp. 55-57, pi. 1). — An account is given of a fungus found on fig 

 leaves at points near Miami, Fla., in 1907 and 1908. The species is considered 

 new and has been designated as 0. ^ci. 



