New Yoek Agricultural Experiment Station. 289 



studies to ascertain if the plants are attractive to the insects for 

 purposes of hibernation and the effects, if any, of cover crops in 

 promoting attacks on the vines early in the spring. Chemical 

 analyses of grapes have shown the effects of injured foliage, due 

 to the work of this pest, on the quality of the fruit. These phases 

 of the problem are of much importance at this time owing to the 

 abundance of the leaf-hoppers for the past two years and the 

 danger that exists of these insects appearing in destructive num- 

 bers in certain of the grape-growing sections. This bulletin is 

 designed to place before the grape-growers of the State the facts 

 recently acquired and recommendations based on them. 



conditions with respect to leaf-hopper during 1912. 



This insect was very abundant during the latter part of the sum- 

 mer of 1911 and it is estimated that in Chautauqua county alone 

 at least one-fourth of the vineyards, representing approximately 

 ten thousand acres, showed extensive feeding on the foliage by this 

 species. The conditions with respect to this pest in other grape 

 regions of the State were similar. The winter of 1911-12 proved 

 to be severe and hopes were entertained that this would cause a 

 high mortality among the hibernating adults. However, with the 

 arrival of spring the leaf-hoppers emerged from their winter quar- 

 ters in great numbers and seriously injured the young foliage in 

 many vineyards. This invasion of the vines caused considerable 

 apprehension among growers and led to more extensive spraying 

 to combat the insect than has heretofore been practised in this 

 region. 



Considering the summer as a whole considerable injury was 

 done to vineyards ; yet the damage was less than was expected be- 

 cause of the cool weather during June, July, August and Septem- 

 ber. The weather conditions during this period were unusual as 

 will be noted from the accompanying record :* The temperature 

 for June was 106 degrees below normal — a daily deficiency of 3.5 

 degrees ; July was slightly below normal ; August gave a deficiency 



* From the Monthly Meteorological Summary for 1912 of the U. S. Weather 

 Bureau, for Buffalo, N. Y., which is forty-five miles distant from Fredonia. 



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