268 PLANT DISEASES 



ing as for brown rot usually controls this trouble. If it appears, 

 spray with lime sulfur, 1-40, or dust heavily with powdered sulfur. 

 LEAF-SPOT (Cylindrosporium padi}. A fungous disease in which 

 the leaves become thickly spotted with reddish or brown spots and 

 fall prematurely. The spots often drop out, leaving shot holes. 



Control. Spray with lime sulfur, 1-40, or with bordeaux 

 mixture, 4-4-50, as for brown rot. 



WINTER INJURY. Trees so injured make a scant growth; many 

 leaves turn yellow and fall about picking time; gum exudes at the 

 crotches and about the trunk; sometimes the bark on the stock is 

 entirely killed, in which case the tree languishes and finally dies. 



Control. It is thought that heavy applications of highly nitrog- 

 enous fertilizers in late summer favor winter injury. Do not 

 stimulate the tree to too active wood development. Cut out the 

 gum pockets and cankers, and paint them with a heavy lead paint. 

 Chestnut. BARK DISEASE (Diaporthe parasitica). A fungous disease, 

 attacking the bark of the American chestnut. Limbs and trunk 

 are girdled, and the tree dies. The disease is present in many of 

 the nurseries. 



Control. Inspect nursery stock very carefully, especially 

 about pruned stubs. Discard diseased trees. Make a careful 

 examination of old trees, especially about old wounds and pruned 

 stubs. If the disease is present, clean out the diseased wood with 

 a gouge, and coat heavily with gas-tar. If the disease has pro- 

 gressed far, cut off diseased limbs or the whole tree and burn at 

 once. Keep all wounds and pruned stubs covered with gas-tar. 

 Chrysanthemum. LEAF-SPOT (Septoria chrysanthemi) . First ap- 

 pears as dark brown spots, which increase in size until the leaf dies. 



Control. Pick and bum diseased leaves. Spray the plants 

 with bordeaux mixture, 4-4-50. 



RUST (Puccinia chrysanthemi). Reddish brown rust pustules on 

 the leaves. 



Control. Avoid wetting the foliage when watering. Spray 

 as for LEAF SPOT. 



Corn. EAR-ROT (Diplodia zece). Several other organisms may cause 

 an ear rot, but this is the more common one. The ear is imper- 

 fectly developed, soft, and overrun with a whitish mold. In 

 many cases the husks and silk are also involved. 



