PEACH SCAB AND ITS CONTROL. 3 
1908) obtained promising results from the use of self -boiled lime- 
sulphur for peach-scab control. The same author (1909) reported 
that this fungicide satisfactorily controlled the disease without objec- 
tionable foliage injury and recommended its use in commercial 
orchards. These results have been confirmed by Scott and Ayres 
(1910), Scott and Quaint ance (1911), and other investigators. 
Thus, while peach scab has received a considerable amount of 
attention from botanists and plant pathologists, the status of knowl- 
edge of the disease has remained fragmentary and incomplete. No 
attempt at a thoroughgoing study of the malady appears to have 
been undertaken, previous work having been confined chiefly to 
descriptions of Cladosporium carpopMlum and of the injuries which 
it induces, to field observations, and to the empirical development 
of control measures. Consequently, the etiology of the disease has 
not been scientifically determined and the detailed life history of 
the causal organism in relation to pathogenesis and to control meas- 
sures has remained obscure. 
The purpose of the investigations reported in this bulletin has been 
to further the understanding of the nature, cause, development, and 
control of peach scab. Accordingly, the effort has been directed 
along four correlated major lines of study, viz, (1) the disease, (2) the 
causal organism, (3) the detailed life history of the causal organism 
in relation to pathogenesis, and (4) control measures. 
Studies of the relationships of peach scab to similar diseases of 
other stone fruits have not been included in this problem, though 
such investigations are now under way. Consequently, only peach 
scab will be considered in this bulletin. 
THE DISEASE. 
GEOGRAPHIC DISTRIBUTION. 
In order to supplement the available published data concerning 
the geographic distribution of peach scab in the United States, a 
brief questionnaire was recently sent to the authorities x of each State 
agricultural experiment station. The disease was reported from the 
following States: Alabama, Arkansas, California, Colorado, Con- 
necticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, 
Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, 
Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New 
York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, 
South Carolina, Tennessee, Texas, Virginia, and West Virginia. 
In foreign countries, scab appears to occur practically wherever 
the peach is grown intensively under normal conditions. However, 
since peach production abroad is relatively of much less importance 
1 The writer wishes to make grateful acknowledgment of his indebtedness to all who cooperated in 
compiling these data. 
