494 
7 corms had brown core bases; 5 of these 
corms had brown vascular strands also. 
Fusarium was recovered from all 7 corms. 
MarGARET Futton: 10 plants 
emerged; all survived and produced new 
corms. Each of the corms had a thin, 
light brown discoloration around the core 
base. Only 1 corm had a discolored vascu- 
lar strand. Three of the corms were cul- 
tured; Fusarium was recovered from all 
of them. 
SpoTLicGHt: 10 plants emerged; all 
survived and produced new corms. One 
corm had a hard core base and pronounced 
vascular discoloration. Two other corms 
had lighter vascular discoloration. Fu- 
sarium was not recovered from _ these 
corms. Seven corms showed no symptoms 
of disease. 
ELIZABETH THE QUEEN: 10 plants 
emerged; all survived and produced new 
corms. Four corms had typical thin basal 
rot lesions; 2 had discolored vascular 
strands but no basal rot lesions. Fusarium 
was recovered from 5 of the 6 affected 
corms. Four corms had no symptoms of 
disease. 
Basal rot isolate 50-23 
Dr. F. E. BENNETT: 6 plants emerged ; 
all survived and produced new corms. One 
corm had a thin basal rot lesion; 1 had a 
brown vascular strand in the top half of 
the corm. Fusarium was recovered from 
both affected corms. Four corms remained 
healthy. 
MARGARET FuLTON: 10 plants 
emerged; 9 survived and produced new 
corms. Eight corms had thin brown dis- 
colorations over the core bases. In 1 corm 
the discoloration extended slightly beyond 
the core. One corm had no symptoms. 
Attempts to recover Fusarium failed with 
all 8 affected corms. 
SpoTLIGHT: 10 plants emerged; all 
survived and produced new corms. Nine 
corms had typical thin diffused basal rot 
lesions. There was no vascular discolora- 
tion. Fusarium was recovered from 8 of 
the 9 affected corms. One corm remained 
healthy. 
ELIZABETH THE QUEEN: 10 plants 
emerged; all survived and produced new 
corms. No disease symptoms developed in 
any of the plants or new corms. 
InLtnois NATURAL History SURVEY BULLETIN 
Vol. 26, Art. 6 
Basal rot isolate 50-26 
Dr. F. E. BENNETT: 8 plants emerged ; 
all survived and produced new corms. 
Seven corms had brown core bases. One 
corm also had a thick brown rot lesion on 
its side; 1 corm had a thin brown rot le- 
sion on its side, and 1 corm had a brown 
vascular strand. One corm had no disease 
symptoms. Fusarium was recovered from 
5 of the 7 affected corms. 
MarGareTt FuLtTon: 9 plants emerged ; 
all survived and produced new corms. Six 
corms had brown core bases; 3 had no 
symptoms. Fusarium was recovered from 
only 1 of the affected corms. 
SPOTLIGHT: 9 plants emerged; 8 sur- 
vived and produced new corms. Two of 
the corms were mummies; 6 had typical 
thin basal rot lesions. Fusarium was re- 
covered from all 6 of these corms. 
ELIZABETH THE QUEEN: 10 plants 
emerged; all survived and produced new 
corms. Two corms had very small, thin 
basal rot lesions. Fusarium was recovered 
from both corms. Eight corms had no dis- 
ease symptoms. 
Noninoculated checks: Three sets of 
checks consisting of 10 corms of each vari- 
ety in each set were planted. 
Dr. F. E. Bennett: 24 plants 
emerged ; 23 survived and produced new 
corms. No disease symptoms developed. 
MaRGARET FULTON: 29 plants 
emerged; all survived and produced new 
corms. No disease symptoms developed. 
SPOTLIGHT: 29 plants emerged ; 28 sur- 
vived and produced new corms. No dis- 
ease symptoms developed. 
ELIZABETH THE QUEEN: 30 plants 
emerged; all survived and produced new 
corms. No disease symptoms developed. 
Fusarium reisolates: The cultures that — 
were recovered from the new corms agreed 
closely in growth type on Wellman’s agar 
with the growth types of the respective 
isolates used for inoculation. 
Variation in Virulence of Isolates. 
—Relative virulences of the isolates used 
in the greenhouse tests were rated numer- 
ically by means of disease indexes com- 
puted as follows: Values were assigned 
to the disease symptoms in the new corms 
and these values were applied in a modifi- 
