FURTHER CULTURES OF HETEROECIOUS 
RUSTS^ 
W. P. Fraser 
Field observations extending over several years, and culture 
experiments during the spring of 1911, furnished evidence that 
the fern rusts of the genus Uredinopsis are heteroecious, and 
have their aecia on Abies balsamea; these aecia being the white- 
spored forms that have passed as Peridermium balsameum Peck. 
The infection experiments during 1911 were inconclusive, so fur- 
ther experiments which are described in the following pages were 
undertaken in 1912 to establish if possible the connection of these 
forms. 
The teliosporic material used in all the experiments was col- 
lected near Pictou, N. S., and was wintered in the open in small 
cheese-cloth bags ; but the culture experiments with this material 
were carried on in the greenhouse of Macdonald College. The 
plants of Tsiiga and Abies used in the experiments were obtained 
not far distant from the college. They were taken into the 
greenhouse in early spring, as soon as the frost was out of the 
ground, and kept in the greenhouse till the young leaves appeared 
and the plants were in the proper stage for infection. As Peri- 
dermium balsameum was never collected in the field within sev- 
eral miles of where the plants used in these experiments were ob- 
tained, and as a number of trees of Tsuga and Abies obtained at 
the same time and place were kept as checks, and all remained 
free from infection, there seems to be no reasonable doubt that 
the trees used in the experiments were free from outside in- 
fection. 
The writer returned to Nova Scotia about the middle of June, 
and the experiments with aeciosporic material were carried on in 
the laboratories of Pictou Academy. The ferns used in these ex- 
periments at Pictou were obtained a week or two before the ex- 
* Read before the American Phytopathological Society at the Cleveland 
meeting, Dec. 31, 1912. 
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