RACIAL STRUCTURE OF FUSARIUM OXYSPORUM F. SP. CUBENSE IN THE CANARY ISLANDS
Results for the old plantations showed that most of the isolates from the diseased plants belonged to VCG 0120, race 4, and did not present any differences in aggressiveness. All the soil isolates but two, which belonged to VCG 0120, represented unidentified VCGs; most of these composed a single member VCG although four compatibility groupings of unidentified VCGs (comprising 4, 4, 2, and 2 isolates, respectively) were also found. All the soil isolates were saprophytic with the exception of the two that belonged to VCG 0120, which showed a degree of aggressiveness similar to that of the plant isolates. For the plantations recently replanted with Grande Naine, most of the isolates obtained from diseased plants also belonged to VCG 0120, race 4, and exhibited the same degree of aggressiveness, whereas the soil isolates were, again, all saprophytic. These results suggest that there are no differences in racial structure between the FOC populations from the two types of plantations studied, and that the pathogen was possibly introduced from Southeast Asia, its area of origin, and spread clonally throughout the Canaries.