22 CIRCULAR NO. 124, BUREAU OF PLANT INDUSTRY. 



favoring the development of molanose and ammoniation arc them- 

 selves the predisi)()sing factors. In quite a number of groves where 

 the splitting, dropi)ing, and decay amounted to perhaps a fifth of the 

 crop, ammoniation was the only kind of rind injury to be found. 

 Once all the details of the cause of ammoniation are known, it may be 

 possible to prevent much of this loss. 



THE RELATION OF MELANOSE TO STEM-END ROT. 



In view of the paper recently published by Floyd and Stevens,* m 

 which some suggestive evidence is given to show that melanose is 

 due to the same fungus that causes stem-end rot, it seems higlily 

 probable that by preventmg melanose at least a portion of the decay 

 can be prevented. 



EXPERIMENTS ON THE PREVENTION OF MELANOSE. 



Some expermients are now under way on the prevention of melan- 

 ose under grove conditions. Lime-sulphur as well as Bordeaux mix- 

 ture is being used as nearly as possible according to the suggestions 

 given in the above-mentioned paper by Floyd and Stevens. In case 

 the disease is prevalent agam this year it will be possible to get some 

 idea of the feasibility of usmg a fungicide for its control. 



DOES STELLATE MELANOSE ON LEAVES HARBOR PHOMOPSIS CITRI ? 



Even in a season like the last, when the leaves, young growth, and 

 fruit of thousands of both pomelo and orange trees are literally cov- 

 ered with melanose roughenmgs, very few fruitmg bodies of the causal 

 fungus were found on the dead twigs of such severely affected trees. 

 That makes one wonder what could have been the source of all the 

 mfectious material required to produce such untold millions of mfec- 

 tions. It appears that ordinarily PJiomopds citri is not to be found 

 in the melanose roughenmgs on the leaves, shoots, or fruits. The 

 mjury resulting in the rough spots is thought to be duo to some 

 enzymotic substance liberated by the spores of the fungus on germma- 

 tion. Tlie melanose spots are usually pinheadlike cushions of cork 

 raised above the general surface of the citrus tissues, but hi some 

 cases a later enlargement of these circular spots occurs, in that three 

 or more short ridges develop as radii about the origmal circular si)ot. 

 This stellate form of melanose was found very abundantly durmg 

 February and March, 191.3, ui one of the smaller orange groves of the 

 Manatee Fruit Co. near Palmetto. Now, smce the fruithig bodies of 

 the Phomopsis are so few on tlie dead twigs of severely affected trees, 



1 Floyd, B. F., and Stevens, H. E. Melanose and stem-end rot, Florida Agricultural Experiment 

 Station, Bulletin IH, 16 p., 9 figs., 1912. 

 ICii-. 124] 



