Abstract: Sixty-seven strains of Rhizoctonia solani were isolated from diseased cotton seedlings sampled from 22 main counties of cotton production in Hebei province. They were divided into two anastomosis groups through hypha mating with standard strain. The frequency of AG-4 was 91. 04% of the tested strains,which indicated that AG-4 was the major anastomosis group of R. solani in Hebei province. While the frequency of AG-2 was 1. 50%.The other five strains belong to non-fusion strains,accounting for 7. 46% in frequency. 6 vegetative compatible groups of AG-4 strains were determined by their behaviors on MPDA (maltose peptone dextrose agar) II medium.Pathogenicity assays of the 67 strains were conducted on cotton seedlings under greenhouse condition. Results demonstrated that AG-4-A displayed the strongest pathogenicity,and AG-2 was the second,whereas AG-4-E and AG-4-F showed the mild pathogenicity and did not cause dead cotton seedling. The pathogenicity of different anastomosis groups and their vegetative compatibility groups as follows: AG-4-A > AG-2 > AG-4-B > AG-4-C > non-fusion > AG-4-D > AG-4-E > AG-4-F.

Key words: Rhizoctonia solani, Anastomosis group, Vegetative compatible group, Assay of pathogenicity

CLC Number: 

• S435.62