PATHOGENICITY AND CROSS-PATHOGENICITY OF FUSARIUM OXYSPORUM ON PROTEACEAE

Fusarium wilt, caused by Fusarium oxysporum, was first reported in 1998 on the genus Protea in the North Western province of South Africa and in Zimbabwe.
Since then it has also been reported from the Canary Islands, Madeira and Chile and might also be a potential risk in Australia.
In South Africa, the genera Protea, Leucospermum and Leucadendron are affected by this disease, which can cause up to 60% loss of plants in a season, if conditions are favourable for infection.
No chemical has been identified in South Africa to effectively control Fusarium wilt of proteas.
Controlling nematode infections and fumigating the soil before planting can reduce losses, but this does not solve the problem.
The most effective long-term control measure will be to cultivate resistant cultivars.
Therefore the long-term aim of this study is to develop a protocol for screening Proteaceae material for resistance or tolerance against Fusarium wilt.
The first objective was to design a protocol for testing the pathogenicity of selected isolates on Protea cultivars.
Different inoculation techniques (sand-bran or millet seed), growth media (Hygromix, peat or orchard soil mix), Fusarium isolates and Protea cultivars (‘Cardinal’, ‘Susara’, ‘Sneyd’) were used in a pot plant trial performed under controlled conditions.
All the variables tested influenced the outcome of the trial, except the inoculation technique used.
The second objective was to test the cross-pathogenicity of the same isolates on other Proteaceae cultivars under controlled conditions.
When the inoculation was performed with an isolate obtained from the same genus as the inoculated plant, the occurrence of wilt symptoms were higher than when an isolate obtained from a different genus was used.

XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Advances in Ornamentals, Landscape and Urban Horticulture

C.M. Bezuidenhout, S.C. Lamprecht

Leucadendron, Leucospermum, Protea

https://doi.org/10.17660/ActaHortic.2012.937.92