32 BULLETIN 805, U. S. DEPARTMENT OP AGRICULTURE. 



seasons of 1915 and 1916 at West Chester, Pa., this date was between 

 June 10 and June 20. It is not safe to delay the appHcation untU 

 the end of the nymphal period, since by that time the insects will 

 have produced sufficient injury to cause the tender terminal leaves 

 to curl, and the result is that the nymphs on the curled leaves will be 

 protected against the spray. 



The nymphs feed on the undersides of the terminal leaves during 

 the entire nymphal period, so the spray material must be directed in 

 such a manner as to wet the underside of the leaves thoroughly. 

 Special care must be taken to see that the foliage of the upper half 

 of the trees and especially the terminals are well sprayed. If a 

 machine with "set nozzles" is used, the lower nozzles should be 

 placed at an angle that will insure a thorough spraying of the lower 

 surfaces of the leaves. 



TREATMENT FOR THE ROSE LEAFHOPPER. 



The injury caused by the rose leafhopper on nursery apple trees 

 is seldom serious enough to warrant a special spray application. 

 This species confines its attack to the undersides of the leaves of the 

 lower half of the trees and the injury is characterized by mottled 

 white or yellowish spots on the foliage. As a result of continued 

 feeding some defoliation takes place which reduces the vitality of 

 the trees slightly. 



Whenever necessary, this* species can be controlled by one spray 

 application of a tobacco insecticide against the first-brood nymphs. 

 A spraying of J pint of 40 per cent nicotin sulphate to each 50 gallons 

 of water with the addition of 2 pounds of soap, made at the time 

 when the maximum number of nymphs are present on the foliage, 

 win give satisfactory results. The most effective time to make this 

 application is when the greatest number of nymphs have reached the 

 third stage, which is three to four weeks earlier than the date for 

 the spraying against the first-brood nymphs of the apple leafhopper. 

 For southeastern Pennsylvania the correct time for spraying the 

 rose leafhopper during the seasons of 1915 and 1916 was from May 

 15 to May 25. 



RECOMMENDATIONS. 



The apple leafhopper can be controlled by spraying against the 

 first-brood nymphs with a tobacco insecticide. A 40-per cent nicotin 

 sulphate solution at the rate of 1-1,500 to which 2 pounds of soap is 

 added to each 50 gallons will so reduce their numbers that injury to 

 the growth of the trees by the later broods wiU not be serious. When 

 it is desirable to use Hme-sulphur solution with the tobacco insecticide, 

 soap must be omitted to prevent burning. The spray should be 

 directed upward so as to wet the underside of the leaves, and par- 



