46 BULLETIN 395, U. S. DEPARTMENT OF AGRICULTURE. 



Supplementary notes by Mr. Waite follow. 



Notes supplementing Table IX. — This list gives most of the commonly grown com, 

 mercial peach varieties of the Middle States in their order of ripening, and compara- 

 tive estimates of scab injury to unsprayed fruit, in percentage of the value of the 

 crop, in average localities from southern Pennsylvania, Maryland, and Virginia west 

 to Missouri and Arkansas. North of this section, and particularly along the northern 

 limit of peach culture, from New England and New York to Michigan, there is con- 

 siderable reduction in the severity of the disease. The damage is distinctly less on 

 light, sandy soils than on heavy soils or even on sandy loams. It is greatly reduced 

 at high altitudes. For example, Bilyeu, before the advent of spraying, was consid- 

 ered wholly unfit for commercial planting below 1,500 feet altitude in the Appalachian 

 Mountain belt, on account of its susceptibility to scab, but could be grown successfully 

 at high altitudes. The disease is somewhat more destructive in the Southern States 

 than in the Middle States, and is generally aggravated in moist localities. Ill arid 

 regions it disappears. 



A peach half covered with confluent scab spots, particularly if cracked open, may 

 be considered as without commercial value. A peach badly spotted, with only 

 one-fotu-th of its area covered, may be considered as of only 50 per cent commercial 

 value in comparison with perfectly smooth fruit. Fruit with even less scab in a sea- 

 son of low prices may be rendered unfit for marketing. With unsprayed trees of 

 Heath, Salway, Bilyeu, Tennessee, and certain seedlings in lower altitudes in the 

 Middle and Southern States it is not rare to have the entire crop rendered commer- 

 cially worthless by scab. 



CONTROL MEASURES. 



SPRAYING. 



Since the serious economic aspects of peach scab began to be recog- 

 nized during the early period in the development of Bordeaux mix- 

 ture, when this newly discovered fungicide was being applied with 

 such marked success in the control of many of the most destructive 

 plant diseases, it is not surprising that the earliest efforts to control 

 this malady consisted almost entirely of spraying experiments with 

 Bordeaux mixtm'e of various formulas. Cobb (1894, p. 386) and Stur- 

 gis (1897, p. 271), apparently on a priori grounds, suggested treat- 

 ments with this fungicide, while Price (1896, p. 840-841) reported 

 decidedly favorable results from three applications of Bordeaux 

 mixture (4-5-50) upon Early China and Mamie Ross. Selby (1898, 

 p. 237-260), in 1895 and 1896, carried out the first extensive spraying 

 experiments, reporting favorable results from the use of Bordeaux 

 mixture. Five years later the same author (1904, p. 67), as the 

 result of seven years' study, states — 



. For scab prevention, in addition to one spraying before blossoming with some 

 effective fungicide, recent observations indicate the need of two applications of weak 

 Bordeaux mixtvu-e [2-2-50] upon trees in foliage; the earlier of these to be made in 

 northern Ohio about June 15; the second, three to four weeks later. 



Although this treatment was efficacious and proved satisfactory in 

 certain sections and under certain conditions, so much host injury 

 resulted that Bordeaux mixture never came into general use through- 

 out the United States as a summer spray for the peach. 



