Mar. 19, 1917 
Peanut-Wilt Caused by Sclerotium Rolfsii 
445 
and bad seed. On the same day that the above seed was planted by 
the laborers the writer planted in each plot one row of seed which he 
had carefully selected from healthy pods of the 1915 crop. Notes were 
taken throughout the season, and it was found that the rows planted 
to carefully selected healthy seed had as many wilted plants as the aver¬ 
age of the rows planted with unselected seed. The writer does not think 
that these data prove that seed is unimportant in spreading S. Rolfsii , 
but it does indicate that the soil of both plots was well infested with 
this organism. The writer anticipates conducting further experiments 
along this line during the season of 1917. 
From what has been observed of the hand-shelling of peanuts for 
seed, it seems reasonable to suspect that 5 . Rolfsii may be carried 
by sclerotia and bits of infected pods which become mixed with the 
shelled seed. This danger would be greatly lessened by fanning the 
shelled seed to remove the trash, or by obtaining heavy clean seed from 
a reliable storage plant which has suitable facilities for thorough cleaning. 
EFFECT OF ROTATION ON THE DISEASE 
With many fungus diseases a 3-year rotation would be effective in 
reducing the amount of disease on the susceptible crop, but from the 
data in Table II it will be seen that this is not true in the case of peanut- 
wilt. 
By reference to Table I, it will be seen that in 1916 peanuts were again 
planted on plots 1 and 2, which were the plots planted to peanuts in 1913, 
the year when the peanut-wilt was first observed. Since 1913, plot x 
has been continuously in peanuts, while plot 2 has grown crops of com 
and crimson clover in 1914 and a fall crop of Irish potatoes in 1915. 
When again planted to peanuts in 1916, plot 2 had a somewhat larger per¬ 
centage of wilted plants than plot 1. There is a possibility that the 
wilt in plot 2 in 1916 was due to infection introduced with the seed and 
trash; but the fact that healthy Valencia seed planted by the writer in 
these two plots also showed a high percentage of disease would indicate 
that a rotation of more than three years is necessary to free a soil from 
S. Rolfsii. 
VARIETAL RESISTANCE TO SCLEROTIUM ROLFSII 
Through the courtesy of Mr. F. E. Miller and Mr. H. C. Thompson, of 
the Office of Horticultural Investigations, United States Department of 
Agriculture, the following varieties of peanuts were obtained: Tennessee 
Red, Valencia, Spanish, African, Virginia Bunch, Virginia Runner, and 
Hog Goober (Worandzia subterranea ). 
To serve as controls, one row of each of these varieties was planted on 
land which had not previously been planted to peanuts. To test their 
varietal resistance to 5 . Rolfsii , from a half to a full row of the different 
varieties was planted in each plot, using every sixth row. These seed 
