206 THE NURSERY-MANUAL 



5 parts powdered lead arsenate, will control the disease. It 

 has been the experience of the writer that, as a rule, the treat- 

 ment of pear buds for leaf-blight is not necessary in the nursery. 

 For budded quince stock, the first treatment should be made 

 soon after the first leaves are developed or when the young bud- 

 shoots are from eight to ten inches high. Subsequent treat- 

 ments should follow at intervals of about two weeks until 

 five or six applications have been made. 



SEPTORIA LEAF-SPOT OF THE PEAR. The leaf-spot of pear 

 is confined to the foliage, and in the nursery the budded stock 

 is most susceptible. 



Description. The spots on the leaves are angular in shape ; 

 the outer part of the affected area is brown or black in color, 

 while the well-differentiated center is light gray, with six to 

 twelve minute black specks which are especially apparent in 

 old lesions. The grayish center is somewhat transparent. 



Cause. The disease is caused by the fungus Mycosphcerella 

 sentina. The black specks (pycnidia) in the center of the spot 

 contain spores that escape and throughout the summer spread 

 the disease. The fungus lives over winter in the diseased 

 leaves on the ground. 



Control. The treatment recommended for the control of 

 the leaf-blight of quince and pear is also effective for the con- 

 trol of the septoria leaf-spot. 



RASPBERRY YELLOWS. This disease is usually found only 

 on red raspberries. The black-caps and purple varieties are 

 seldom affected. Diseased plants are stunted, sickly and 

 make a bushy growth. The leaves are abnormally small and 

 the margins of the upper leaves curl downward. One of the 

 striking symptoms of the disease is the mottled appearance 

 of the foliage ; at first it is light colored, then gradually changes 

 to darker green and finally is reddish bronze. 



