September, 1955 FORSBERG: 
test were used also in the 1952 test. The 
severity indexes for the rots caused by the 
same four isolates on corms of these vari- 
eties in the 2 years are shown in table 16. 
In 17 cases the rot indexes were lower in 
1952 than they had been in 1951, in 5 
cases they remained the same, and in 2 
cases only they were higher. 
A third test was made in 1953 when all 
40 isolates were used on the varieties Pic- 
ardy and Spirit of St. Louis. The results 
obtained with these varieties in 1952 and 
1953 are shown in table 17. In the tests 
on Picardy the rot indexes in 27 isolates 
were lower in 1953 than in 1952, in 4 
FUuSARIUM DISEASE OF GLADIOLUS 
485 
they were higher, and in 9 they remained 
the same. With Spirit of St. Louis the 
rot indexes in 5 isolates were lower in 
1953 than in 1952, in 7 they were higher, 
and in 28 they remained the same. The 
indexes remaining unchanged included 7 
instances in Picardy and 25 in Spirit of 
St. Louis in which no rot was produced 
in either year. 
Although no attempt was made to 
maintain the same conditions for all tests, 
it is not likely that laboratory conditions 
varied greatly during the three tests. Dif- 
ferences in corm lots used in different 
years may have been partly responsible for 
Table 17.—Severity indexes for the rots produced in 2 or 3 successive years by 40 isolates 
of Fusarium on two gladiolus varieties. Indexes were derived from the formula on page 481. 
PICARDY | Spirir or Sr. Louis 
IsOLATE = 
1951 1952 | 1953 1951 1952 1953 
A See aN eR spc ceastat ees a Sid 2500 — 25.0 2520 
Aas Es MMAR ees. shit lae ok sya — 0.0 0.0 a= 0.0 25.0 
TUE. len oo Oe ee ETE —- 25.0 0.0 — 0.0 0.0 
A ae fkcns ad Seay nc dt ca —- 0.0 0.0 a= 0.0 0.0 
AVEO) oS a EE pe a ee er ane —- 125 0.0 — IDS 12.5 
EAN eso IS Oty = 0.0 0.0 — 0.0 0.0 
Act Eat SAMs ee ea — 50.0 0.0 a= 0.0 0.0 
AVIV). RNS OR IRs eee saber ree ae - 25.0 0.0 — 0.0 0.0 
ENOL AN A 1 Ae ie nen ae eee a — 100.0 75.0 — 0.0 0.0 
ANOLE 8 Ee Ae ek a ae — 0.0 0.0 — 0.0 0.0 
BO LOIGS © 2k a Re re an ee _ 0.0 0.0 — 0.0 0.0 
ANG). 53 Ske RIGS Eee _- 100.0 0.0 os 0.0 0.0 
OPS IP MESE oes isk CER sees. ese — 2520 50.0 — 0.0 0.0 
Oba 2a 55 ee eee — 75.0 0.0 — 0.0 0.0 
SQM ach nt na Rn ah — 25.0 0.0 _— 0.0 0.0 
S(O] a Seo a me ee aS 100.0 SLY 75.0 125 0.0 0.0 
i (S2 Giarmre ie cer ate ale ah. — 75.0 25.0 os 0.0 (5n0 
USS oe ee cee 5, nea REE -— 62.5 50.0 — 0.0 0.0 
AS STUN 0 2s Se tee ea — 0.0 62.5 0.0 0.0 
TS ot: GELS Ae ee ee —- Ts), 100.0 oe 0.0 0.0 
Aes Sie oe ene A 8 SES cs _ 0.0 0.0 0.0 0.0 
CVE dS AS Ne a ieee eS “+ 2520) 125 _ 0.0 0.0 
Aveo (9): ook red La eel Tet incre —- 100.0 S25 — 0.0 0.0 
Ay eS Ri es he, rae a ~- 87.5 100.0 — 0.0 25 
LASS ye lle a ene eat en — Bie 15 — 0.0 0.0 
CATES ORE 4 0 2) Te ee oe — 100.0 75.0 0.0 0.0 
ONO a Se _— 100.0 75.0 — 0.0 0.0 
AS) Pe RE ee Os SE cosh os — 100.0 75.0 -- 0.0 50.0 
BOA 5 hae OR a ee a 100.0 75.0 — 0.0 25.0 
AS ip he IN, cath haces 100.0 100.0 87.5 25 0.0 0.0 
AOAC Gus ON ele ee aaa ae ene _ 100.0 0.0 — 0.0 0.0 
S067 ee ee eee — 100.0 25.0 — S7n5 37/25 
SQ) = See eae ea ene 100.0 100.0 75.0 11} 25) eS S75 
EOI 6 atte SO» ae ae —- 0.0 0.0 = 0.0 0.0 
ATID Brae ON PROT Are aie othe — 87.5 TAD) — 87.5 25.0 
a, ay ee ee ee _ 100.0 100.0 _ DES 0.0 
EMD) ns Se A ae 75.0 87.5 125 87.5 75.0 37.5 
N19) Vago — 87.5 Sie os 25.0 0.0 
SDRAM = Tea i se oe ene — 100.0 62.5 ~- 1205 0.0 
SED Gemeente ta eaters invA sse — 100.0 75.0 — 0.0 12.5 
