174 INTERNATIONAL CONGRESS OF VITICULTURE 



vineyard, lime-sulphur must be used alone, unless in combination with 

 tobacco or a special type of lead arsenate. (4) The alkali sulphides and 

 polysulphides have some points of advantage over lime-sulphur solution for 

 the reasons that soap may be used with them as a spreader and that they 

 can be used with a greater variety of sprays. 



Prof. Bioletti: "There is a common belief among grape growers that 

 sulphur after being placed on the vine loses its strength. Is there any 

 possible change that the sulphur undergoes that could be interpreted as 

 making sulphur lose its strength?" 



Prof. Gray: "There is a great difference of opinion on this subject." 



Mr. C. J. Wetmore, Mr. Frank Henry and Mr. Geo. E. Lawrence, of Lodi, 

 California, gave personal experiences of the use of sulphur in their different 

 vineyards. 



President Alwood: "In the East we are using sulphur very largely in 

 treating the brown rot in the peach and plum orchards. We use it in a com- 

 bination of lime solution. We slack the lime and add the sulphur. I do not 

 know whether it has been applied to the vines in the West or not. We use 

 about 16 pounds of sulphur to 100 gallons of wash, and for a second applica- 

 tion about 8 pounds of sulphur to 100 gallons of wash." 



MORNING SESSION, JULY 13, 1915. 

 GRAPE INSECTS IN CALIFORNIA. 



By H. J. QUAYLE, 



Entomologist, University of California, Citrus Experiment Station, 

 Riverside, California. 



While there is more or less injury done to the grape by insect pests every 

 year in California, there is at present no insect that requires such universal 

 treatment as is necessary for the powdery mildew or Oidium. Nevertheless, 

 insect pests have been one of the most important factors in connection with 

 the development of the viticultural industry of the State. The phylloxera 

 has caused probably not only a greater actual loss than any other single 

 thing, but it has necessitated important changes in viticultural methods. 

 The various phases of the question of resistant stock, which have been some 

 of the fundamental viticultural problems of the State for many years, have 

 for their basis the proposition of insect control. The phylloxera has de- 

 stroyed upwards of 50,000 acres of vines in California, but this loss is now 

 very largely past because of general replanting of the vineyards on resistant 

 stock. Next to the phylloxera, the grape leaf-hopper has been the most in- 

 jurious insect of the grape in this State, but unlike the phylloxera, the injury 

 by the grape leaf-hopper has not diminished, but rather increased with the 



