﻿THE GRAPE LEAFHOPPER IN THE LAKE ERIE VALLEY. 39 



It was noted that this condition obtained during the dry fall of 1910. 

 The "blackleaf 40 " tobacco extract does not appear to carry so much 

 of this sticky substance, and owing to the greater dilution that is 

 possible in its use the dilute spray liquid is almost clear; hence there 

 is not the likelihood that it will leave the undesirable stain on the 

 ripened fruit. It should be stated, however, that neither of these 

 extracts is likely to leave the unpleasant stain or odor on the fruit 

 if applied in the early part or middle of July, which is usually the 

 period at which the maximum benefit is to be derived from them in 

 the destruction of the nymphs. 



SPRAYING APPARATUS. 



Various types of spraying machinery are used by the vineyardists 

 of the Lake Erie Valley. It was on account of the depredations of 

 the grape, rootworm, requiring a spray application to the upper sur- 

 face of the foliage, that the use of spraying machinery in vineyards 

 became general. The sprayer in general use for this work is of the 

 tractor type (PI. Ill, fig. 1), the power being generated either by a 

 chain or an eccentric gearing connecting the wheel and the pump. 

 Thus in order to maintain a uniform high pressure with this type of 

 machine it is necessary to keep it in motion. Although most of these 

 machines are supplied with a large air chamber so that the pressure 

 is held quite steady and does not vary with every stroke of the plun- 

 ger, yet as soon as the wheels of the machine stop turning the pressure 

 drops quite rapidly. 



Other types of sprayers in use for vineyard work are compressed-air 

 power outfits, gasoline-engine power outfits, and steam power outfits. 

 With all of these latter types the pressure is independent of the rate of 

 movement of the machine through the vineyard rows. 



In making spray applications against the nymphs of the grape 

 leafhopper it is necessary to apply large quantities of spray liquid to 

 the underside of the infested grape leaves. Where the foliage is quite 

 dense the amount of spray required for thorough work may amount 

 to from 200 to 300 gallons per acre, whereas in making applications 

 to the upper surface of the foliage against the beetles of the grape 

 rootworm thorough work can be done on quite dense foliage with 

 about 100 to 125 gallons of liquid per acre, and this may be accom- 

 plished while the team is being driven slowly. 



During the seasons of 1911 and 1912 all of the types of spray ma- 

 chinery previously mentioned were observed in use in spraying against 

 the grape leafhopper, and in the hands of careful operators effective 

 work was accomplished with all of them. 



It should be stated that in all cases observed, with the exception 

 of the steam-engine power outfit, all of the spray applications were 

 made by the trailer method. That is, the operator directed the spray 



