306 



[Pieris rapae, L.]. If the caterpillars are not very numerous, the 

 arsenical may probably be safely reduced to 10 lb. 



Macrosiphiim soJanifoUi, Ashm. (potato aphis) appears to be the 

 most difficult species to control. Dehydrated copper lead arsenate 

 containing 2 per cent, nicotine used at the rate of 50 lb. per acre killed 

 52-3 per cent, of the Aphids infesting the tips of the growing shoots 

 and 83-2 per cent, when used at the rate of 90 lb. per acre. Nicotine 

 and soap used at the rate of 100 lb. per acre destroyed 85-5 per cent. 

 All applications appreciably checked the rapid development of the 

 Aphids on the growing shoots and apparently afforded noticeable 

 protection to the leaves. 



De Long (D. :\I.). The Boom Nozzle System and the Traction Duster 

 as Factors in Grape Leal Hopper Control. — //. Econ. Ent., Geneva, 

 A'. Y., XV, no. 1, February 1922, pp 87-90, 1 plate. 



During 1920 and 1921 great damage was caused to grapes along 

 the south-eastern shore of Lake Erie by Typhlocyba {Erythroneura) 

 comes, Say. The attacked foliage dried prematurely and curled up 

 before the grapes had ripened, causing them to have a red appearance 

 and sour flavour and thus diminishing their market value. Owing 

 to the unsatisfactory results obtained with the existing arrangement 

 of the spraying nozzles, a new method has been devised, which promises 

 better results. In the new arrangement the driver sitting on the spray 

 tank holds a |-inch horizontal pipe about 7 feet long, connected 

 with the spray tank and extending over the top of the row. From 

 the horizontal pipe a 3-foot pipe connected by 3 feet of rubber 

 hose extends vertically almost to the ground on either side of the row 

 at a distance of about 3| ft. apart. Seven disk nozzles were used. 

 One was placed pointing downwards from the horizontal pipe midway 

 between the vertical pipes and directly over the grape row ; three 

 on each of the vertical pipes ; one at the extreme lower end pointing 

 upwards at an angle of about 45° ; another about H ft. above directed 

 upward and slightly backward ; and one about 3 ft. from the bottom 

 directed upward and slightly forward. The nozzles were attached 

 by means of " T's " and an " L " in the case of the extreme lower 

 one. The spreading of the vertical pipes was prevented by attaching 

 a W' eight to the end of each. The upper nozzles on the vertical pipes 

 were found to be unnecessary. The main points in the construction 

 of this apparatus are that the lower nozzle must be as close to the ground 

 as possible as the lowest portions of the plants are often most heavily 

 infested by the nymphs ; the nozzle should be upturned at an angle 

 of approximately 45", which however will vary with the vineyard, 

 a difference of 5° often causing 15 to 20 per cent, difference in the 

 killing ; the lateral nozzles should be alternated slightly forward and 

 backward. One of the great advantages of this arrangement is that 

 the upturned nozzles lift the leaves and thereby thoroughly cover 

 the lower surface. As compared with the trailer method the chief 

 advantages are the reduced time and expense. 



Experiments with the traction duster have given varied results. 

 A 2 per cent, nicotine dust used with both Bordeaux and lime and 

 appHed at the rate of 60 lb. and more per acre killed both the adults 

 and nymphal stages, but the same treatment applied to another plot 

 the following evening gave very inferior results. The difference may 

 have been entirely due to the temperature and humidity conditions, 

 and there may have been a difference in the percentage of nicotine 



