First report of Fusarium crown and root rot of tomato caused by Fusarium oxysporum f.sp. radicis-lycopersici in Turkey

In the spring of 1998, tomato plants (Lycopersicon esculentum) growing in a commercial greenhouse in the province of Adana (Cukurova region, southeastern Turkey), exhibited symptoms of swelling at the crown, with some orange and brown lesions, root-rot and interior decay of the lower stem. The lesions progressed upwards for 10-15 cm and where the lower parts of the stem withered, fungal sporulation was visible. Such plants wilted within 2-3 weeks. These symptoms are typical of Fusarium oxysporum f.sp. radicis-lycopersici and different from the vascular wilt caused by F. oxysporum f.sp. lycopersici, as described by Jarvis & Shoemaker (1978). During the 1999-2001 growing seasons, the site of the first finding in Adana and five other polytunnels in the province of Icel were examined. Macroconidia from the stem surfaces of 48 tomato plants, exhibiting disease symptoms, were spread on potato dextrose agar and single, germinating conidia were isolated. These monoconidial isolates of F. oxysporum were subjected to the vegetative compatibility grouping (VCG) test, using the following tester strains of F.o. radicis-lycopersici: FORL-IID and FORL-IIE (VCG 0090/subroup II), FORL-C696/A3 and FORL-C710/A62 (VCG 0090/subgroup III), FORL-C544 and FORL-C758 (VCG 0091/subgroup I), FORL-C69E3 and FA-222 (VCG 0091/subgroup II), CRNK-676 and CRNK-678 (VCG 0092) and FORL-C623/4 (VCG 0096) (Katan & Katan, 1999). Nine isolates were compatible with the testers of VCG 0090/subgroup II and two with the testers of VCG 0091/subgroup I. The remaining 37 isolates were self-compatible and did not belong to any of the VCGs tested. These isolates were not examined further. The two VCGs found are cosmopolitan, however the subgroup II of VCG 0090 have only been reported from Italy (Di Primo et al., 2001), Israel (Katan et al., 1991) and Cyprus (Ioannou and Katan, unpublished). No conclusion can be drawn regarding the exact origin of the disease in Turkey.

The 11 isolates belonging to VCG 0090II and VCG 0091I were used to inoculate a local tomato variety (Urfa) using a root-dip method (Korolev et al., 2000). The experiments were conducted in a growth chamber at 24±2oC (12 h photoperiod) for up to 21 days. The isolates were found to cause yellowing, wilting and death of 1-week-old seedlings by 10-15 days after inoculation. F. oxysporum was re-isolated from the infected plants.

Occurrence of Fusarium crown and root rot disease caused by F. oxysporum f.sp. radicis-lycopersici has been reported from the Mediterranean region, Europe, USA and Japan (Katan & Katan, 1999). This is the first report of F. oxysporum f.sp. radicis-lycopersici in Turkey.

This research was financed by a grant from the Scientific and Technical Research Council of Turkey (TUBITAK, Project NoTARP-2371) and The Hebrew University of Jerusalem.