European Journal of Horticultural Science

Pathogenicity of Some Species of Fusarium and formae speciales to China Aster and Carnation

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Summary
The aim of this research was to test, whether F. oxysporum f. sp. dianthi can cause wilt disease of China aster, the main causal agent of which is known to be F. oxysporum f. sp. callistephi. In addition, the pathogenicity of F. culmorum, F. lateritium and F. solani in China aster was investigated as well as the interactions in the pathosystems China aster/F. oxysporum f. sp. dianthi and carnation/F. oxysporum f. sp. callistephi.
Various isolates of F. oxysporum f. sp. dianthi were pathogenic to China aster. So were various F. oxysporum f. sp. callistephi isolates to carnation. Both ornamentals showed typical and identical disease symptoms. Percent infection depended on the isolate's virulence and the cultivars tested. In the pathosystems
China aster/F. oxysporum f. sp. dianthi or carnation/F. oxysporum f. sp. callistephi percent infection was much lower than in the pathosystem China aster/F. oxysporum f. sp. callistephi.
The development of visible disease symptoms on plants inoculated with F. culmorum, F. lateritium and F. solani did not start before 40 days after inoculation, but then persisted over the whole test period (120 days). During this period, individual plants randomly showed symptoms of chlorosis and loss of turgescence. However, black and brown discolourings of the diseased plant's stems, typical of the wilt disease, were not observed. All three Fusarium species showed different virulence to the China aster plants tested. Dependent on the cultivar, there was strong variation. These results demonstrate that the role of F.oxysporum f. sp. dianthi, F. culmorum, F. lateritium and F. solani should not be underestimated. In China aster production, these species of Fusarium can aggravate loss of plants due to infection by F. oxysporum f. sp. callistephi.

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