Aug. 2, 1920.] Agricultural Gazette of N.S.W. 581 



A Condition resembling American ^^ Peach 



Rosette/^ 



W. A. BIRMINGHAM, Biologist's Assistant. 



In March, ] 920, peach twigs with abnormal foliage were submitted to the 

 Biological Branch for the determination of a suspicious condition and its 

 treatment. The condition resembled very closely that of " peach rosette," 

 which is prevalent in some parts of the United States of America, but 

 whicli has not been met with in this State before. 



Critical examination of the material failed to reveal the presence of any 

 organism, and the grower was asked to submit further specimens and to state 

 whether he had noticed the fruit fall prematurely. He was unable to do either, 

 as thR trees had only been budded the previous season with wood obtained 

 from America. Sufficient time had not elapsed to enable the trees to present 

 the other characteristics of rosette, namely, the yellowing of leaves in early 

 summer, and the premature dropping of the fruit. 



The condition must be regarded as a very suspicious one, on account of the 

 bunching condition of the leaves and the fact that the wood with which the 

 trees were budded was imported from America. 



It would be impossible to detect rosette or "peach yellows" (a condition 

 closely allied to it) in imported wood — a fact that emphasises the necessity of 

 keeping a close watch on trees budded with wood obtained from America, in 

 order that the introduction and spread of disease may be prevented. 



Rosette was first observed in Georgia in 1879, and was first thought to be 

 yellows. It was later found in other States — Kansas, South Carolina, 

 Arkansas, and elsewhere. 



Rosette differs from yellows in having the bunches with narrow leaves 

 and the internodes quite short, so as to bring the leaves in bunches or 

 rosettes along the branches and at the ends of the twigs. 



It acts quickly, killing the diseased trees in six to twenty-four months. It 

 generally shows when the buds first open in spring, and when the leaves are 

 older they have a stiff appearance and inrolled margins. The affected foliage 

 turns yellow early in the summer, and the fruit falls prematurely. 



The cause is not known, but, like yellows, rosette is probably due to a filter- 

 passer, that is, an organism which our highest magnifying lenses would fail to 

 detect. The disease is contagious, and can be spread by buds from diseased 

 trees and by root grafts. It seems that if the smallest piece of living 

 matter from a diseased tree is established on a healthy one, the disease will 

 follow. 



