21 



Hemedial Measures. 



The grape leaf-hopper has proved to be a difficult pest to combat 

 successmlly. Various practices have been proposed, such as the use of 

 trap la,nterns to burn at night, the raking and burning during winter of 

 fallen leaves and trash in vineyards, the use of sticky shields or fans to 

 catch the adults as they fly from the vine on being disturbed, and in 

 California the use of insect nets for the same purpose. 



Extensive field experiments were made by Professor Slin^erland and 

 his assistants in 1902 in Chautauqua vineyards against this pest, and 

 fully recorded in Bulletin 215 already cited. He found that large 

 numbers of the hibernated adults could be caught on sticky shields 

 carried along each side of the row, the insects being frightened out by 

 disturbing the vines. Tliis work is done early in the season, before 

 oviposition takes place to any extent. A light wooden frame is made, 

 7 or 8 feet long by 4 feet high. To the crosspiece at the bottom, 

 which should be up from the ground about a foot, are fastened several 

 stiff wires of the shape of a hayrake tooth. These are fastened so that 

 the points curve inward and downward to the ground at base of 

 plants when the shield is held in place beside the vines. The whole 

 framework, including the wires, is covered with oilcloth which is 

 coated with a sticky substance, made by using melted resin, 1 quart, 

 and castor oil, 1 pint. 



Early in the season the insects will be found mostly on the lower 

 leaves and the frame need not be high. As the higher leaves are 

 invaded the height of the frame must be increased. In controlling the 

 insects in this way it is very important to catch the over-wintering 

 adults before egg laying has begun, thus greatly reducing the number 

 of progeny to appear later, and the operation of catching the insects 

 must be repeated at frequent intervals. 



Extensive tests with sprays were also made, and it was found prac- 

 ticable to destroy the young wingless hoppers or nymphs with a whale- 

 oil soap solution, the soap being used at the rate of 1 pound to 10 gallons 

 of water. The spraying must be done very thoroughly, covering the 

 under surface of the leaves, as only those nymphs are killed which are 

 actually hit with the spray. This work should be begun when it is 

 observed that the young are becoming common. In the Chautauqua 

 and Erie grape belts this will be early in July. There will be less 

 foliage to treat at this time than if the work be deferred until some- 

 what later. Repeated applications may be necessary, especially if 

 the work is not thoroughly done. It has been noted by Mr. Fred 

 Johnson, of this Bureau, that whale-oil soap leaves a stain on the 

 fruit at picking time, greatly lessening its market value for dessert 

 purposes. It is likelj^ that an 8 to 10 per cent kerosene emulsion 

 could be used, which would obviate this difficulty, and would prove 

 equally effective in killing the young hoppers. 



Thorough cleaning up of fallen leaves and trash in vineyards during 

 the winter will undoubtedly destroy many hibernating adults, and 

 if this work be extended to adjacent areas where the insects are 

 likely to find shelter, the reduction in their numbers will be materi- 

 ally greater. Where practicable the burning over of adjacent mead- 

 ows, wood lots, and spaces along fences is very advisable. It has 

 been observed that in vineyards in which clean culture is prac- 

 ticed, all grass and weeds being kept down thi'oughout the season, 



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