PROTECTING PLANTS 211 



the fruit cracks. In the treatment of this disease it is of prime im- 

 portance to secure a free circulation of air about the fruit. AccompHsh 

 ■ this by avoiding low sites, by pruning, and by removal of windbreaks. 

 Spray as for brown-rot, with lime-sulfur, 8-8-50. 



Yellows is a so-called " physiological disease." Cause unknown. 

 Contagious, and serious in some localities. Known by the premature 

 ripening of the fruit, by red streaks and spots in the flesh, and by the 

 peculiar clusters of sickly, yellowish shoots that appear on the limbs 

 here and there (Fig. 215) . Dig out and burn diseased trees as soon as 

 discovered. 



Pear diseases. — Fire-blight kills the twigs and branches, on which 

 the leaves suddenly blacken and die but do not fall. It also produces 

 cankers on the trunk and large limbs. Prune out blighted branches as 

 soon as discovered, cutting 6 to 8 in. below the lowest evidences of 

 the disease. Clean out limb and body cankers. Disinfect all large 

 wounds with corrosive sublimate solution, 1 to 1000, and cover with 

 coat of paint. Avoid forcing a rapid, succulent growth. Plant the 

 varieties least affected. 



Pear scab is very similar to apple scab. It is very destructive to 

 some varieties, as, for example, Flemish Beauty and Seckel. Spray 

 three times with lime-sulfur, 1-50, or bordeaux, 3-3-50, following the 

 general methods employed for apple scab. 



Plum and cherry diseases. — Black-knot is a fungous disease. The 

 spores of the fungus are carried from tree to tree by the wind and thus 

 spread the infection. Cut out and burn all knots as soon as discovered. 

 See that the knots are removed from all plum and cherry trees in the 

 neighborhood. 



Leaf-spot is a disease in which the leaves become covered with red- 

 dish or brown spots and fall prematurely (Fig. 211) ; badly affected trees 

 winterkill. Often, the dead spots drop out, leaving clear-cut holes. 

 Bordeaux, 5-5-50, or lime-sulfur, 1-40. For cherries, four applica- 

 tions : first, just before blossoms open ; second, when fruit is free from 

 calyx ; third, two weeks later ; fourth, two weeks after third. In 

 plums it may be controlled by two or three applications of bordeaux, 

 3-3-50, or self-boiled lime-sulfur. Make the first one about ten days 

 after the blossoms fall and the others at intervals of about three weeks. 

 This applies to European varieties. Japan plums should not be 

 sprayed with bordeaux. 



