GRAPE INSECTS 415 



A spring holds the boom pressed away from the sprayer so that 

 the nozzle is thrown into or under the vines as the sprayer is 

 moved along the row, but can swing back when any obstacle 

 is encountered. The exact arrangement of the nozzles will 

 depend on the age and size of the vines as well as on the style 

 of trimming. This apparatus is well adapted for doing efficient 

 work in fairly level vineyards, but on steep hillsides, where it is 

 impossible to keep the sprayer from swinging down close to the 

 lower row, the use of trailing hose and extensions as described 

 above will be found more practicable. 



Much good may be accomplished, in preventing leaf-hopper 

 injury, by destroying their hibernating quarters in the vicinity 

 of vineyards. Grassy fence corners and overgrown hedge rows, 

 in which fallen grape leaves are collected by the wind, should 

 l)e removed or burned over. Clean farming also helps to control 

 other insects and should be practiced wherever possible. 



As stated above, the adult hoppers begin their work on the 

 lower part of the vine, and it is on these lower leaves that great 

 numbers of the eggs are deposited early in the season. Many 

 of these lower canes or suckers are usually removed in June. 

 If this operation could be delayed until just before spraying time, 

 the first week in July, great numbers of the eggs would be de- 

 stroyed. 



In California, where the adult hoppers are more destructive 

 in the spring and where many of the vineyards are not trellised, 

 it has been found practicable to capture the adults in mosquito- 

 screen cages smeared on the inside with kerosene or crude oil. 

 The cages are made large enough to cover a vine; one side is 

 left open, but the bottom is covered with a screen, a slit being left 

 for the base of the vine. The cages are operated with the open 

 side facing the wind ; when the cage is placed in position, the 

 vine receives a jar, and the hoppers, trying to escape, are caught 

 on the oily screen. It is said that from 85 to 95 per cent of the 

 hoppers can be captured by this method. 



