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THE MONTHLY BULLETIN. 



PEACH YELLOWS AND PEACH ROSETTE. 



By J. B. S. Norton, Agricultural Experiment Station, College Park, Maryland. 



On account of its long history o£ destructiveness, its insidious nature and the 

 mystery of its cause the yellows is the most dreaded of all peach diseases. The 

 active propaganda, legal as well as educational, against it for many years, has also 

 brought more notoriety to the yellows. As a matter of fact, the brown rot and 

 possibly other ever present and less apparent diseases, in all probability, cause more 

 actual financial loss to peach growers ; but the loss of whole trees and, at times of 

 special yellows outbreaks, the destruction of whole orchards in a few years, brings it 

 to the attention of growers much more than the others. 



The yellows disease is known only on the North American continent, and in the 

 cooler parts; although the southern line of its distribution extends as far as Georgia, 

 it is found only in the higher altitudes, and here, as well as further north, it follows 

 more or less closely a line of similar temperatures. It occurs mostly on peach and 

 nectarine, but has been observed on almonds, apricots and Japanese plums. 



The yellows was noticed as early as 1700, and is thought to have started some- 

 where in Pennsylvania, near Philadelphia, and has apparently spread in all directions 



Fig. 87. Fruit showing effects of peach yellows. The peach on the left is a per- 

 fectly healthy specimen, while that on the right is affected with yellows. The 

 spots are a bright red in color. (U. S. Dept. of Agriculture.) 



from that center to its present limits, which include Canada and New England as 

 far north as peaches are grown, and from there south to Maryland and Delaware. 

 the line of southern limit passing through central Delaware and across Maryland 

 toward the southwest, then extending northward again up the Chesapeake Bay 

 and again southwest from about Annapolis and into Virginia a few miles south 

 of Washington, D. C, and thence south along the mountains far into the Southern 

 States and back again west of the mountains and through the Central States, where 

 its southern limit has not been certainly marked, to as far west at least as Arkansas 

 and eastern Kansas; the northern limit in the West is not definitely known, but as 

 in the East is no doubt determined by the limit of successful peach culture. 



In the affected region in ordinary years there is a loss of one to three per cent of the 

 trees, or generally less than this in well cared for orchards where the diseased trees 

 are promptly removed. But there have been a number of yellows epidemics (1791, 

 1800-07, 1817-21, 1845-58, 1874-76, 1886, 1S88, and 1907-09) iu which the loss has 

 been much more. 



The foliage characters of the disease are sometimes difficult to separate from the 

 similar effects of other diseases. The yellows is most clearly recognized by its effect 

 on the fruit. When trees in fruit are attacked the first indication of the disease is 

 the prematuring of the fruit, this premature fruit having peculiar red spots on the 



