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. 510, collected at Bowden, Jamaica, Novem- 
ber 18, 1902, on flower-bud spathes of Cocos nucifera, 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 J/acrophoma 
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 
