476 



Griffon and Maiiblanc, in 1909, working in the French Congo, have 

 shown by comparison of various specimens that three other species are 

 identical with Diplodia cacaoicola: these are Bolryodiplodia Tlieobromae, 

 Patouillard, 1892, the oldest synonym, described on fruits of cacao in 

 San Domingo, Lasiodiplodia nigra,, Appel and Lambert on cacao in 

 Samoa, and Macrophoma vesfita,, Prill eux and Delacroix, 1 894, on 

 roots of cacao in equatorial America ; these authors have also shown 

 that according to the present system of classification the fungus is a 

 Lasiodiplodia which they have named Lasiodiplodia Theohromae. More 

 recently Fetch has described from Ceylon a " die-back " disease of 

 Hevca hrasiliensis, the later stage of which he has attributed to Bot- 

 ryodiplodia elasticae. Fetch ; he has pointed out that this species'is prob- 

 ably identical with Diplodia cacaoicola {Lasiodiplodia ^T/ieobro/nae, 

 Griffon and Maublanc). Inhere has, therefore, been from time to time 

 a muhiplication of names for one and the same fungus. 



A careful comparison of the fungus causing the "die-back" 

 disease, or what is better known as the " stem and branch " disease 

 of Hevea hrasiliensis in the Straits Settlements and Malay States with 

 the fungus occurring on cacao in West Africa has quite recently been 

 made at the Department of Agriculture at Kuala Lumpur. After an 

 examination of several specimens it has been concluded that the two 

 fungi are identical. The characters which were considered were the 

 nature of the stroma and perithecia, the measurement of the pcrithe- 

 cia, of size and shape of the spores and he the paraphyses ; in these the 

 two fungi were indistinguishable from each other 



The cause of the occurrence of these synonyms is the absence of 

 a constancy or fixation of characters on which the divisions between 

 the genera are based. In Diplodia the perithecia are scattered, in 

 Botryodiplodia they are aggregated on a stroma which is smooth and 

 in Lasiodiplodia they are included in a stroma which is covered with a 

 soft ielt of hairs. In the fungus under consideration there is a 

 tendency for the perithecia to be scattered on the younger parts of 

 the stem, while on the older parts they are usually aggregated on 

 a stroma : the stroma is in some cases almost smooth, while in others, 

 and especially when the fungus is producing perithecia in large num- 

 bers, the stromata are covered by a soft felt of hairs. The perithecia 

 always contain paraphyses mixed with the spore-bearing hyphae. 



This variability in characters has led to the multiplication of 

 names for the fungus and has tended to prevent the recognition of its 

 wide geographical distribution and of its variety of hosts. 



In a previous work* the authorwas careful to point out that 

 judging from analogy the Diplodia on cacao might w^ell be 

 expected to belong to an ascigerous fungus which was probably a 

 member of the Sphaeriaceae. To investigate this point a number of 

 cultures were made in artificial media ; several of these are now more 



A Handbook of Fungus Diseases of W^est Indian Plants, p ii, 



