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J. J. TAUBENHAUS 
Further microscopical study of our sectioned sweet potato material 
shows that the necks of nearly all the pycnidia of Lasiodiplodia theo- 
bromae have hairs (fig. 23). The same is true for Lasiodiplodia 
tuhericola (figs. 18) and Diplodia natalensis (fig. 25). In the latter 
two, however, the hairiness is not so pronounced and sometimes it may 
be absent altogether. Similar observations were made by Griffon 
and Maublanc (10) and by others. From this it is evident that the 
genus Chaetodiplodia cannot stand and that Diplodia alone should 
be retained. 
According to Jonge and Dorst (13) and others, the hairiness of 
the neck of the pycnidia is largely dependent upon cultural conditions. 
They state that lack of moisture tends to produce glabrous necks and 
much moisture has the opposite effect. My studies do not support 
these conclusions, since the inoculated sweet potatoes were kept in 
moist chambers. Under similar conditions Lasiodiplodia theobromae 
produced hirsute pycnidia and L. tubericola produced either glabrous 
or sparingly hirsute pycnidia. The determining factor in the produc- 
tion of hirsute or glabrous pycnidia is yet to be worked out. 
Botryodiplodia was distinguished from Lasiodiplodia in the ar- 
rangement of the pycnidia. In the former they are caespitose, in the 
latter they are borne in a stroma. It has been shown that the genus 
Lasiodiplodia is untenable. In further study of the sectioned material 
it is seen that the pycnidia in L. tubericola may be borne singly, in a 
stroma, or cespitose (fig. 14). The same also holds true for Diplodia 
gossypii (fig. 22). This therefore clearly indicates that the genus 
Botryodiplodia, too, should be dropped, its characteristics being 
included in the genus Diplodia. 
The genus Diplodiella differs supposedly from the other genera here 
mentioned in that the pycnidia are superficial. This distinction does 
not hold. In further studying sectioned material, it is seen that 
Diplodia gossypii often produces a number of pycnidia which are 
distinctly superficial (fig. 22). Because of these facts the genus 
Diplodiella is not tenable. It is evident that the genus Diplodia 
under different hosts and climate may take on some or all of the 
characteristics of the more recent genera Chaetodiplodia, Lasio- 
diplodia, Botryodiplodia, and Diplodiella. The common fungus 
Lasiodiplodia theobromae has actually been placed by different workers 
in all of these genera except Diplodiella. 
Griffon and Maublanc (10) suggest that Diplodia tubericola (E. & 
