MICHIGAN ACADEMY OF SCIENCE. 
51 
WINTER STAGE OF SCLEROTINIA FRUCTIGENA. 
J. B. Dandeno. 
Monilia fructigena is one of the commonest of the rot-producing fungi. 
Almost any kind of fleshy fruit may be made to serve as a host, and inocu- 
lation is always easy. From inoculations made artificially, the conidial, 
or summer stage, is the only one produced. In fact, the name Monilia was 
given to this summer stage as though this were the whole plant, and not 
simply one phase of fits existence. The genus Sclerotinia was also well 
known,. but it was not known that there was any connection between Monilia . 
and Sclerotinia until 1902, when J. B. S. Norton, in the Transactions of the 
Academy of Science of St. Louis described it, giving demonstrations showing 
that Monilia was only a summer, or conidial stage of a Sclerotinia. The 
discovery was a very important one, not only from a scientific point of view, 
but also from the economic side. The whole life history of a parasite being 
once known, the matter of checking it becomes an easier one. However, 
this fungus is such an extremely vigorous form that a winter stage is not 
nearly so necessary as for many other forms. Ungerminated spores may 
remain in a room for years and years, and then, when opportunity offers, 
germinate. So that, even though the winter stage be materially checked, the 
disease will likely occur from year to year, though doubtless much less ex- 
tensively. 
This winter stage, or Sclerotinia stage, as it is sometimes called, is the 
condition of the fungus to which particular reference is here made. Up to 
the present, so far as the writer is aware, there has been considerable difficulty 
in obtaining specimens for laboratory use; and because of the importance 
of the fungus from an economic point of view, laboratory material is es- 
pecially desirable for students in horticulture. And if this winter stage were 
sufficiently abundant, there could be no better form for class illustration in 
morphology, to show one of the fungi imperfect! and in complete form. 
The Monilia stage is the fungus imperfectus, so-called, and this with the 
Sclerotinia stage, the complete form. Moreover, the Sclerotinia stage, 
which we might now call the ascus stage, is so very easy to see, and to man- 
ipulate, that it is especially desirable. The Monilia stage, which is the con- 
idial stage, is so extremely abundant and hardy that there could be no better 
example for the use of the student. The only reason, therefore, why the 
plant has not found its way into university laboratories for class use is that 
the ascus stage was so extremely rare. But it is not rare; it is plentiful, if 
one knows where to find it. In the spring of 1907, a basketful, of which 
figures* 1, II, and III, are samples, was collected in an area of two or three 
square yards. In 1906, a considerable quantity was obtained in the plowed 
ground under plum trees, but a large area had to be gone over, in order to 
obtain a few specimens. 
In the fall of 1905 diseased plums affected abundantly with the conidial 
stage were “planted ” in different places with a view toward obtaining plenty 
of material for laboratory study. Upon examination of this material, in 
♦These photographs were kindly made by Prof. Pettit from fresh material collected by the writer 
about May 10, 1907, in the college orchard. 
