348 EXPERIMENT STATION RECORD. [Vol. 41 



first has more oxidizing power than the second, and both combined have more 

 than either separately. A partial disintegration of cellulose is noted in diseased 

 bark, also the disappearance of cyanogenic glucosid and a lower content of 

 starch, calcium oxalate, and tannins. Diseased bark has a higher percentage 

 of dry matter, lipoids, alcohol-water-insoluble residue, and total nitrogen than 

 healthy bark. Other contrasts are detailed. 



The greater oxidase activity of diseased bark is thought to be due to the 

 combined activity of the oxidases of fungus and host, to lower acidity, and 

 possibly to a greater degree of dispersion of the oxidizing agent. The lower 

 tannin content of diseased bark is iwssibly another contributing factor. 



The effect of crown gall upon a young apple orchard, L. Gkeene and I. E. 

 Melhus {loiva Sta. Research Bui. 50 {1919), pp. 147-176, figs. 30). — This bul- 

 letin is a record of progress in a study of the effect of crown gall upon an apple 

 orchard from the time it was set out imtil it became of bearing age. Data have 

 been collected on the relative influence of various types of galls upon the annual 

 growth of the trees and on the amoxmt and position of the galls in relation to 

 the growth and percentage of stand in the orchard. The orchard In question 

 was planted in 1912 with 310 trees infected with crown gall and 246 normal 

 trees. The varieties Wealthy and Jonathan were used in the experiment, and 

 at planting time it was noted that the Wealthy trees were infected with hard 

 gall and very little hairy root, while the Jonathan were infected with both 

 kinds of gall. 



At the end of five years it was found that more of the crown gall infected 

 apple trees were alive than normal trees, and the experiment confirmed the 

 general idea that the variety Wealthy is more susceptible to crown gall than 

 the Jonathan. In the experiment, the trees infected with gall did not show 

 nearly so rapid growth as normal trees. Data are presented which show that 

 croA^Ti gall greatly retards the growth activities of young apple trees, as mani- 

 fested by a reduction in the amount of increase in trunk diameter, and in the 

 number, length, thickness, and weight of twigs. It is claimed by the authors 

 that twig measurement is a much more accurate and valuable index of the effect 

 of crown gall than trunk diameter growth. Large galls appeared to be more 

 injurious than smaller ones. Small galls on the underground portion of the 

 tree did not seem to injure the twig growth materially. Fruit spurs developed 

 earlier on badly infected trees than on the normal trees. Galls occurring on 

 stock and union appeared to be equally harmful, while those on secondary roots 

 were less so, and hard galls were less injurious than soft ones. 



[Spraying at the Neog-a Station, Illinois, 1915—16], W. S. Brock {Trans. 

 Ind. Hart. Soc. 1916, pp. 69-81, flffs. S). — This includes a brief account, with dis- 

 cussion, of dust spraying for apple scab since its first employment about 1905 

 of a mixture containing fine sulphur 35 per cent, lead arsenate 15 per cent, and 

 hydrated lime 50 per cent. Some details of the 1915 trials near Neoga suggest 

 that the dust spray can compare favorably with the liquid form. A report is 

 also given of the 1916 experiments at the same place, the main substance of 

 which has been noted previously (E. S. R., 38, p. 551). There appears to be 

 need of a better fungicide than powdered sulphur. Clean fruit can be obtained 

 with standard liquid sprays if properly applied. 



Brown rot, its importance and control, E. B, Benson {Ann. Rpt. State Hort. 

 Soc. Mich., Ji6 {1916), pp. 44, 4-'>). — This is a discussion of brown rot (said to 

 attack practically all varieties of peach, plum, and cherry) and of prevention 

 thereof as regards orchard control and cooperation, particularly in regard to 

 packing, loading, and shipping. 



Control of cherry leaf spot, J. W. Roberts and L. Pierce {JJ. S. Dept. Agr., 

 Farmers' Bui. 1053 {1919), pp. 8, figs, 6), — ^A description is given of the leaf 



