Fusarium oxysporum f. sp. fragariae; A MAIN COMPONENT OF ...

Fusarium oxysporum f. sp. fragariae; A MAIN COMPONENT
OF STRAWBERRY CROWN AND ROOT ROTS IN WA.

Root and crown rots are
important diseases of
commercial strawberry
crops. Several fungi have
been reported causing
considerable yield reduction
worldwide. The fungi,
Phytophthora spp.,
Verticillium spp., Fusarium
spp. Gnomonia fragariae and
Colletotrichum spp. are
known to be important
pathogens. (D'Ercole et
al.1989; Tezuka and Makino
1991; Freeman et al. 1997;
Maas 1998; Morocko et al.
2006).

‣ Strawberry fields were surveyed, diseased and
asymptomatic plants were collected randomly
‣ Visual examination was conducted and crown of
each plant was dissected lengthwise and roots were
examined for disease symptoms
‣ Pathogen detection from crown and root tissues,
using various common and selective media.
‣ Phytophthora and Pythium detection, using baiting
technique
‣ Pathogenicity test
Material and methods

Fig. 2. F. oxysporum f. sp. fragariae. A, Sporodochia with monophialides
macroconidia and B, Mature macroconidia. Scale bar = 25 µm
A

Pathogenicity test
The pathogenicity of 10 Fusarium isolates was
tested on Fragaria × ananassa cv. Camarosa,
Lycopersicon lycopersicum cv. Petula and Cucumis
sativus (Lebanese cucumber) in a glasshouse
experiment. Strawberry runners and 4-week-old
seedlings of tomato and cucumber were inoculated
by dipping the roots in a spore suspension ( 10 5
spores/mL) before planting. Controls were dipped in
tap water.

Isolate
ID.
Pathogenicity test of 10 F. oxysporum isolates
detected from strawberry fields north of Perth
Sample
location
Cucumis
sativus
Lycopersicon
lycopersicum
Camarosa
Cv
2 Site 1 NP NP P
24 Site 1 NP NP HP
10 Site 2 NP P NP
36 Site 2 NP NP HP
35 Site 3 NP NP NP
43 Site 3 NP NP HP
48 Site 4 NP NP P
54 Site 4 NP NP HP
82 Site 5 NP NP HP
104 Site 5 NP NP P

Fig. 3. Phytophthora cactorum. A, Oogonia with paragynous antheridia
B, Sporangiophore and sporangia. Scale bar = 20 µm.
B
B

Fig. 4. Phytophthora. cactorum. Germinated and proliferated
sporangia showed by arrow. Scale bar = 20 µm.

Result: Average percentage of fungi associated with
root and crown rots of Camarosa cultivar
Recovered Fungi
Total recovery %
Diseased
Healthy*
Crown Roots Crown Roots
Fusarium oxysporum
f. sp. Fragariae 74.0 20 4.0 1.0
Phytophthora spp. 21.0 5.0 1.5 0.5
Pythium spp. 8.0 18 5.0 8.0
Phoma spp. 3.3 1.0 0.0 0.0
Rhizoctonia spp. 4.3 9.0 2.0 4.0
Colletotrichum spp. 1.5 1.0 0.0 1.0
Macrophomina spp. 4.0 12 1.0 0.5
Others 7.0 5.0 2.0 4.0

Conclusion
Result of the tests and consistency of the isolated
fungi, indicated that Fusarium oxysporum f. sp.
fragariae is a main component of strawberry
crown and root rots, however combination of
isolated fungi may have been involved in crown
and root rot complex.

ACKNOWLEDGMENTS
I would like to thank Dennis Phillips and
Sandra Mack for their support and technical
assistance and WA. strawberry industry for
financial support.