[From the Kulletin of the 1 okki:\ 1!< hank al Club, 31 ; 551-554,//. 3J October, 1904.] 



Relationship of Macrophoma and Diplodia 



Julia T. Emerson 

 (With plate 25) 



In December, 1902, Mr. Earle brought back to the New 

 York Botanical Garden from Jamaica, West Indies, various collec- 

 tions of cocoanut affected with diseases. One set was handed 

 over to the writer to see how it would develop when grown in 

 cultures. It was no. jio, collected at Bowden, Jamaica, Novem- 

 ber 18, 1902, on flower-bud spathes of Cocos nucifcra, labelled 

 " dying of wasting disease." The spathes were covered with 

 black spots just visible to the unaided eye, which proved to be 

 pycnidia of Macrophoma and Diplodia, so closely associated 

 that from one point both the hyaline unicellular Macrophoma 

 spores and the brown two-celled Diplodia spores could be secured. 



In March, 1903, cultures were started from the spathes by 

 scraping off some of the black pycnidia where Macrophoma spores 

 had previously been found, examining with a microscope and 

 transferring a few spores to ordinary neutral agar. In the same 

 manner cultures were taken from spathes where Diplodia spores 

 had been seen. In this way two sets of cultures from each kind 

 of spore were obtained, with reasonable assurances that they 

 started one from pure Macrophoma spores and the other from 

 pure Diplodia. 



At first only agar and potato were used as media, then bread 

 and milk, bread and water and pith and blade of cocoanut leaf 

 were added. All the cultures were kept in a dark room where 

 the temperature was uniformly at about 24°C. In five days or 

 less after sowing spores or mycelium on agar, vigorous, spreading 

 colonies of silky hyphae were evident. When they were still 

 young, however, it was found best to transfer them to one of the 

 other media; for this fungus will not develop well on agar alone, 

 active growth ceasing in a week or ten days and a few dark 

 chlamydospores being the only result ; whereas on potato and the 

 other materials the growth is vigorous and rapid from the begin- 



551 



