Control of fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici race J3 by grafting to KNVF and KVF, rootstocks of the interspecific hybrids between Lycopersicon esculentum * L. hirsutum.

Abstract

Due to the similarity in the external symptoms and environmental conditions for the disease development of tomato Fusarium wilt (race J3) and tomato brown root rot (Pyrenochaeta lycopersici), it is often difficult for tomato growers to distinguish them from each other without phytopathological tests. The interspecific hybrids between Lycopersicon esculentum×L. hirsutum, commonly named KNVF or KVF were tested for the possibility of using them as differential plants to diagnose the diseases. Two tomato rootstocks (KNVF and KVF) were found to be resistant to single or multiple inoculation with the two pathogens (Fusarium and Pyrenochaeta) at almost the same level. These results indicate that it is difficult to use the rootstocks as differential plants. Roots of KNVF on which Fukuju 2, a Japanese tomato variety, was grafted and planted in soil infested with the causal fungus of tomato Fusarium wilt (race J3), remained clean and showed only mild lesions suggesting resistance to the infection with the fungus. On the other hand, the roots of non-grafted Fukuju 2 become severely infected and the tops of the plant wilted. From the result, the grafting of a horticultural variety on KNVF was found to be useful to control tomato Fusarium wilt (race J3) in practice.