THE GKAPE LEAFHOPPER IN THE LAKE ERIE VALLEY. 39 
It was noted that this condition obtained during the dry fall of 1910. 
The u 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 (PL III, 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 
