Insect Pests and Plant Diseases.' 



199 



PLUM. 



is the same as brown rot of peach, 

 and should be treated in the same 

 way. (Fig. 173.) 



This is the same as leaf-spot of 

 cherry and may be controlled by 

 two or three applications of Bor- 

 Make the first one about ten days 

 after the blossoms fall and the others at intervals of 

 about three weeks. This applies to European varie- 

 ties. Japan plums should not be sprayed with Bor- 

 deax. See Geneva Bulletins 98 and 117. 



is the same disease as black knot of 

 Black-knot cherries and is controlled in same 

 way. For control of this disease by 

 spraying see Cornell Bulletin 81. 



Brown-rot 



Leaf-spot 

 deaux, 5-5-50. 



Fig. 173. Brown-rot on 

 plum. 



POTATO. 



There are different kinds of potato blight and rot. The most 

 Blight and rot. important are early blight and late blight — both fungous dis- 

 eases. Early blight affects only the foliage. Late blight kills 

 the foliage and often rots the tubers. Two serious troubles often mistaken for 

 blight are: (i) Tip burn, the browning of the tips and margins of the leaves due 

 to dry weather; and (2) flea-beetle injury, in which the leaves show numerous 

 small holes and then dry up. The loss from blight and flea-beetles is enormous — 

 often, one-fourth to one-half the crop. For blight, rot and flea-beetles spray with 

 Bordeaux, 5-5-50. For addition of insect poisons see potato flea-beetles. Com- 

 mence when the plants are 6 to 8 inches high and repeat every 10 to 14 days 

 during the season, making 5 to 7 applications in all. Use from 40 to 100 gallons 

 per acre at each application. Under conditions exceptionally favorable to blight 

 it will pay to spray as often as once a week. See Geneva Bulletins loi, 123, 

 221, 241, 264, 267, 279 and 290. 



is caused by a fungus that 

 Scab attacks the surface of the 



tubers. It is carried over 

 on diseased tubers and in the soil. In general, 

 when land becomes badly infested with scab 

 it is best to plant it with other crops for sev- 

 eral years. See Vermont Bulletin 85 and 

 Maine Bulletin 141. 



QUINCE. 



This is a fungous disease 

 Leaf and Fruit producing round, reddish- 

 Spot, brown spots on the leaves 

 and fruit. Spray three 

 times with Bordeaux as for apple and pear 

 scab. See Cornell Bulletin 145. (Fig. 174.) 



Fig. 174. Fruit-spot on quince. 



