CERTAIN ELEMENTS IN NURSERY PRACTICE 213 



Control. The control of the tarnished plant-bug in the 

 nursery is still an unsolved problem. 



APPLE LEAF-HOPPER. The leaf-hopper (Empoasca mali) 

 may attack the foliage of apple, currant, rose, gooseberry, 

 raspberry and numerous other plants. These insects (Fig. 224) 

 suck the juice from the leaves, causing them to curl and to 

 assume a mottled yellowish appearance. The insects work 

 mostly on the undersides of the leaves. Feeding on the terminal 

 leaves of the growing shoots in the latter part of June, July and 

 August, they may retard the growth and thus cause such trees 

 as apples to be stunted and undersized. 



Control. It is difficult to hit the young hoppers in the 

 curled leaves by spraying and this method of treatment is not 

 profitable. Dipping badly infested stock with a soap solution, 

 one pound in 8 gallons of water, kills most of the young hoppers. 

 The dipping should be done in the latter part of June and again 

 about a month later. In Missouri nurseries the hoppers are 

 sometimes captured on sticky shields mounted 

 on a two- wheeled cart drawn by a horse. 



SAN JOSE SCALE. The San Jose scale 

 (Aspidiotus perniciosus) attacks practically 

 all deciduous fruit and ornamental plants and 

 is often very destructive in the nursery. 

 The insect may be recognized by two forms 

 of scales on the bark and fruit (Fig. 225). IB '^ 



The largest scales are about -^ of an inch in FlG 2 24. The 

 diameter, nearly circular, gray, with a central apple leaf-hopper, 

 dark nipple surrounded by a yellowish ring. 

 The smaller scales are nearly black with a central gray dot 

 surrounded by a black depressed ring bordered by a grayish 

 ring. Usually the bark appears reddish in color around the 

 scale. When abundant the scale forms a crust on the bark. 



