For 32 years, cotton grown in NSW has been monitored for Verticillium wilt, with isolates of Verticillium dahliae Kleb. stored in the NSW Department of Primary Industries culture collection. An increase in disease severity in the 2013/14 season suggests a more virulent pathogenic strain may have been introduced. Eight V. dahliae isolates were selected for vegetative compatibility group (VCG) analysis using molecular assays and nit mutant testing. Two of the eight isolates were identified as the highly virulent defoliating VCG1A, making this the first record of VCG1A in Australia.
- Verticillium wilt