360 EXPERIMENT STATION RECOED. [Vol.38 



The beet leaf-hopper and the curly leaf disease that it transmits, E. D. 

 Ball {Utah Sta. Bui. 155 (1911), pp. S-56, figs. 32).— This is a summary of the 

 present status of knowledge of the beet leaf-hopper and the curly leaf disease, 

 including the author's investigations, presented in connection with a biblio- 

 graphy of 20 titles. 



It is pointed out that punctures of the beet leaf-hopper cause this specific 

 disease of sugar beets and that it has never been produced except through the 

 punctures of a beet leaf-hopper. The conclusion that it is transmitted by the 

 beet leaf-hopper has been confirmed by several investigators. "If a single 

 leaf-hopper is applied to a beet for five minutes, the curly leaf disease will 

 appear after about two weeks, if conditions are favorable. Cold, wet weather 

 will stop the development of further symptoms of curly leaf on a slightly dis- 

 eased plant or prevent their development on a previously healthy one, even if 

 a number of leaf-hoppers are kept thereon. . . . Leaf-hoppers taken from wild 

 plants did not transmit the disease until they fed on diseased beets. Three 

 hours on a beet rendered them pathogenic, but they could not transmit until 

 after an incubation period of one or two days. It is probable that some wild 

 plant carries the disease, and leaf-hoppers coming from this plant are able to 

 transmit it to the beets. 



"A large number of leaf-hoppers, early attack, hot weather, and clean culti- 

 vation are favorable to curly-leaf development. The converse of these factor.*:, 

 together with frequent cultivation, early irrigation, and shade or weeds are 

 unfavorable. Seed growing is doubly hazardous in curly-leaf areas. Loss from 

 curly leaf may be largely prevented by avoiding dangerous areas, by planting 

 small acreages in a ' blight cycle,' by time of planting, by not thinning just as 

 the leaf-hoppers appear, and by knowledge of conditions on breeding grounds. 

 Parasites doubtless assist somewhat in controlling the leaf-hopper, but to be at 

 all effective should be introduced into the permanent breeding grounds. The 

 outlook for the immediate future in the intermountain and coast regions is 

 favorable ; for the plains region, doubtful ; and for the Glendale, Tulare, and 

 Columbia-Snake River region, serious." 



Mango hopper control experiments, E. Ballard {Agr. Jour. India, 10 (1915), 

 No. 4, pp. 395-398). — Idiocerus niveosparsus is the cause of great annual loss 

 to mango growers of Chittoor and Salem, a really severe attack resulting in 

 the total loss of the crop and the greatly diminished vitality of the trees. Upon 

 emerging from the egg the young hoppers feed at once upon the leaf or flower 

 shoots. In a badly attacked mango grove the trees are covered with their 

 honeydew, the flower shoots blacken and wither, and no fruit is set. 



In control experiments fish-oil soap appeared to be superior to crude oil 

 emulsion 1 : 10, and cheaper. The results of spraying experiments on 55 trees, 

 presented in tabular form, indicate that spraying is profitable. 



Mango hopper control, P. J. Westek (Philippine Agr. Rev. [English Ed.1, 9 

 (1916), No. 2, pp. 159, 160; abs. in Internat. Inst. Agr. [Rome'], Internat. Rev. 

 Sci. and Pract. Agr., 7 (1916), No. 12, p. 1862).— In briefly reviewing the article 

 by Ballard above noted relating to the control of Idiocerus niveosparsus in 

 India, the author calls attention to the fact that mere or less damage is done 

 annually to the mango crop in the Philippines by /. niveosparsus and /. clypealis. 

 In some years in certain districts the entire crop is destroyed. 



Insecticide spraying for the mango hopper, T. V. Ramakbishna Ayyar 

 (Madras Agr. Calendar, 1917-18, pp. 72-74, fiffs. 2). — A brief account is given 

 of the control work of the previous year with the mango leaf hopper. Quite 

 satisfactory results were obtained from the use (1) of crude oil emulsion and 

 (2) of fish-oil rosin soap, both used at the rate of 1 lb. to 10 gal. of water. It 



