Race 6 of the Cotton-Wilt Fusarium from Paraguay
Pathology, University of Georgia
G. M. ARMSTRONG and JOANNE K. ARMSTRONG, Department of Plant
College of Agriculture, Georgia Station, Experiment 30212
and methods have been given elsewhere
(1).
ABSTRACT
Cultivars of cotton (Gossypium
Fusariumfrom
hirsutum L., G. barbadense L., and G.
ARMSTRONG, G. M., and J. K. ARMSTRONG. 1980. Race 6 of the cotton-wilt
Paraguay. Plant Disease 64:596.
arboreum L.), tobacco (Nicotiana
tabacum L.), alfalfa (Medicago sativa
was
and
a
plants
Fusariumoxysporum f. sp. vasinfectum was isolated from stalks of diseased cotton This is the first
L.), and okra (Abelmoschus esculentus
cultivars.
okra
and
identified as race 6 by the reactions of cotton, tobacco, alfalfa,
L.) were used in the race differentiation in
report of the appearance of race 6 outside Brazil.
F. oxysporum f. sp. vasinfectum (Table
1). Their reactions after inoculation with
the Paraguayan isolate are given in
f. sp.
vsporum
Paraguay.
Fusarium
oxy
Stalks of diseased cotton plants were
Table 2.
vasinfectum (Atk.) Snyd. & Hans. was
received recently from Todd Mathieson,
The susceptibility of cultivars Rowden
race was
its
a
nd
stalks,
the
from
isolated
of the experiment station of the Instituo
hirsutum) and Clemson Spineless
(G.
present
the
n
ir
6
race
identified as
Agronomica Nacionale, Caapuce,
okra and the resistance of cultivars
investigation.
Coastland (G. barbadense) and Rozi (G.
Race 6 was reported re(cently in Brazil
arboreum) showed that the isolate did not
United
the
in
d
foun
been
not
has
but
(1)
the
in
used
Table 1. Reactions of cultivars
belong to races 3 or 4 but was similar to
materials
and
sp.
v
f.
oxysporum
reviev
States. A literature
differentiation of races of Fusarium
races 1 and 2. It differed from races 1 and
vasinfectum
2, however, since it did not cause wilt of
Races
cultivars Grimm alfalfa and Burley 5
after
symptoms)
al
(exterm
Table 2. Wilted plants
a
tobacco. That it was not race 2 was shown
1 2 3 4 5 6
inoculation with Fusarium oxysporum f. sp.
Cultivar
by the resistance of flue-cured Gold
race 6 from Paraguaay
Gossypium hirsutum
b
S S R
Acala
S R
S
Rowden
G. barbadense
R R R
Ashmouni
R R S
Coastland
S S S
Sakel
G. arboreum
R R S
Rozi
Abelmoschus esculentus
S S R
Clemson Spineless
Nicotiana tabacum
S S R
Burley5
R S R
Gold Dollar
Medicago sativa
S S R
Grimm
aSee Ibrahim (1).
bs = susceptible, R = resistant, - = not
vasinfectum
R
R
R
-
R S
- R S
S -
S
R
R
-
S
R R -
R
R
R -
R
R
tested.
0191-2917/80/06059601/$03.00/0
@1980 American Phytopathological Society
596
-
Plant Disease/Vol. 64 No. 6
Cultivar
Cotton
Rowden
Auburn 623
Coastland
Rozi
Okra
Clemson Spineless
Alfalfa
Grimm
Tobacco
Burley 5
Gold Dollar
Cassia tora
External
syl nptoms
Plants
tested
(%)
(no.)
96 a
26
12
17
20
0
10
58
I2b
12
17
0
12
0
0
12
30
10
'Mild external symptoms in one or two leaves.
bVery marked internal discoloration in three of the
five plants that did not have external symptoms.
Dollar tobacco, which is susceptible to
race 2. The susceptibility of the cultivar
Rowden also showed that the isolate was
not race 5. Therefore, the isolate was race
6, similar to the race in Brazil.
An isolate of race 6 from Brazil has
been deposited with the American Type
Culture Collection as ATCC 36198 (1).
Seed of Burley 5 and Gold Dollar tobacco
have been deposited with Dr. V. A.
Sisson, Tobacco Investigations, USDA,
SEA, Beltsville, MD 20705.
LITERATURE CITED
1. ARMSTRONG, G. M., andJ. K. ARMSTRONG.
1978. A new race (race 6) of the cotton-wilt
Fusarium from Brazil. Plant Dis. Rep. 62:421-423.