1917] DISEASES OF PLANTS. 849 



The organism was found parasitic on summer squashes, causing a bliglit of 

 the flowers and a rot of the fruits. The disease has been the cause of very 

 considerable losses. The infection of the fruit is said to occur for the most 

 part by the passage of the fungus from the fading corolla to the young squash. 

 In addition, it is believed that various species of bees and striped and spotted 

 cucumber beetles play some part in disseminating the disease. The fungus has 

 also been found on the flowers of cucumber, althea, okra, cotton, and other 

 malvaceous plants. 



Arsenical injury through the bark of fruit trees, D. B. Swingle and H. E. 

 MoBKis {V. 8. Dept. Agr., Jour. Agr. Research, S {1917), No. 8, pp. 283-318, pis. 

 6). — The authors report a series of investigations carried on at the Montana 

 Experiment Station to determine the possibility of arsenical injury to sprayed 

 fruit trees and the conditions under which injury would occur. Trees were 

 treated with a number of arsenical compounds, the application being made to 

 branches of various sizes, trunks, crowns, and roots. 



As a result of their investigations, the authors claim to have established con- 

 clusively that arsenical compounds used as insecticides can be made to injure 

 the crowns of trees under conditions very similar to those that result from .some 

 orchard practices. It was found that the periderm on the smooth bark of apple 

 trees is practically impervious to arsenical solutions, but that such solutions 

 may be admitted through wounds, lenticels, or latent buds, in which case more 

 or less injury will follow. As the trees become older and the bark rougher the 

 cracks made in its production will admit arsenical solutions to the inner tis- 

 sues, which will be injuretl. Roots and branches of equal size and with similar 

 bark are about equally susceptible to arsenical injury. If the injury is rapid, 

 very definite longitudinal streaks will be produced in the bark and sapwood, 

 but if the injury is slow, the streaking is not so evident. Paint applied to fresh 

 wounds offers a partial but not complete protection. The injury caused by 

 arsenical compounds is not necessarily due to impurities they may contain. 



Diseases of deciduous fruit trees, R. E. Smith {Proe. Fruit Growers' Conv. 

 Col., ^7 (1915), pp. 257-263). — This includes a discussion of gummosis as an 

 expression of injury, of bad cultural conditions, or of various causes more or 

 less unfavorable to the health of the tree. It also deals with pear blight and 

 its variability and control by vigilance and careful early pruning. 



Peach yellows and little peach at Vineland, M. A. Blake and C. H. CoN- 

 NOBS (New Jersey Stas. Rpt. 1915, pp. 51-53, pis. 2). — A report is given of ob- 

 servations regarding peach yellows and little peach on the peach orchards estab- 

 lished at Vineland (E. S. R., 20, p. 1037), one having been planted in 1907, an- 

 other in 1908, and a third in 1912. From the different orchards, 5.5, 11.8, and 

 0.8 per cent of the trees, respectively, have been killed by the diseases in ques- 

 tion. No varietal difference as to susceptibility to these diseases has been 

 noted. The authors recommend that trees be removed as soon as symptoms of 

 either disease appear. In the experimental orchards no tree planted in a posi- 

 tion from which a diseased tree had been removed failed to grow and no re- 

 planted tree has become diseased. 



Plum pockets, E. Rabat£ (Tie Agr. et Rurale, 6 (1916), No. 22, pp. 388-391, 

 figs. 7). — Briefly discussing plum pockets caused by Exoascus pruni, the author 

 recommends the removal and destruction of all diseased fruits, and the disin- 

 fection of the tree in January with a solution containing 10 per cent of iron 

 sulphate and 2 per cent of copper sulphate, repeating the disinfection after 

 blooming occurs. 



Little leaf of the vine, F. T. Bioletti and L. Bonnet (V. 8. Dept. Agr., Jour. 

 Agr. Research, 8 (1917), No. 10, pp. 381-398, pis. 4, figs. 2). — In a contribution 

 from the California Experiment Station the authors describe a disease of 



