216 PLANT DISEASES 



the curl can be controlled the first year. The second year control 

 should be complete. The secret of control of leaf-curl lies largely 

 in the thoroughness with which the work is done. A number of 

 spray substances may be used. A single thorough application 

 before the buds swell in the spring is sufficient. Every bud 

 must be covered and from all sides. Lime-sulfur as applied for 

 San Jose scale will control curl. Commercial lime-sulfur, 1-20; 

 bordeaux mixture, 4-4-50; or a simple solution of blue vitriol 

 in water, 2-50, are all specifics. 



LEAF-RUST. See under PLUM (p. 279). 



LITTLE-PEACH. A disease that in its early stages resembles 

 yellows. It differs from yellows in producing small fruit 

 that matures later than normally. Fruit does not have the small 

 red spots characteristic of yellows, nor are there slender sickly 

 branches. The cause of this disease is unknown. Apparently 

 spreads more rapidly than yellows and commonly destroys the 

 affected tree sooner. Occurs in the northern states. 

 Preventive. As for YELLOWS (see next page). 



POWDERY MILDEW (Sphcerotheca pannosa). A whitish powdery 

 growth on the young shoots and leaves, and whitish spots on the 

 fruit. 



Control. Self-boiled lime-sulfur as for ROT. 



ROOT-GALL, ROOT-KNOT, CROWN-GALL, HAIRY-ROOT (Bacterium 

 tumefaciens) . Hairy roots or tumerous outgrowths on the roots 

 and root crowns ; sometimes occurs on trunks and limbs. Pri- 

 marily a nursery disease. Does not seem to be a serious disease 

 on peaches in the North, but is reported as very serious in the 

 South. Attacks a wide range of orchard plants, including apple, 

 pear, brambles, grape, etc. 



Control. Reject all stock showing symptoms. 



ROSETTE. An obscure southern disease of peach trees and some 

 kinds of plums, characterized by bunchy growths containing very 

 many rolled and yellowish leaves which fall prematurely. The 

 tree dies the first or second year. There is no premature fruit as 

 in yellows. It is often accompanied by gummosis of the roots. 

 The disease is communicable by budding, and it may enter through 

 the roots. All affected trees should be exterminated. Known 

 in South Carolina, Georgia, Kansas, and Arkansas. 



