First report of the presence of Verticillium dahliae VCG1A in Australia

Abstract

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.

The Verticillium wilt problem in Australian cotton

“…The average incidence of Verticillium wilt has generally been low throughout NSW. The incidence rose from 5.5% in 2013/2014 to 7.1% in 2014/2015 and 6.3% in the 2015/2016 season (Chapman et al 2016).…”

“…It was previously thought that only one VCG type, ND VCG4B, was present in Australia, but in 2014, ND VCG2A was identified (Smith et al 2014). Following the discovery of ND VCG2A, analysis of V. dahliae historical samples taken from the NSW Department of Primary Industries culture collection revealed the presence of the D VCG1A (Chapman et al 2016). The D VCG1A has been the cause of severe disease and crop loss overseas ).…”

“…The average incidence levels of Verticillium wilt caused by V. dahliae in Australian cotton are relatively low but yield losses can vary between 10 and 62% in some fields (Holman et al 2016). However, the recent discovery of the defoliating VCG1A and the disease severity of the non-defoliating VCG2A present an additional problem for management of Verticillium wilt as incidences rise (Chapman et al 2016;Dadd-Daigle et al 2020;Jensen and Redfern 2017;Kirkby et al 2013).…”

Investigating the defoliating‐like (DL) VCG2A pathotype of Verticillium dahliae through identification and prediction of secreted proteins from genomes of Australian isolates

“…Verticillium dahliae is a highly destructive soilborne fungal plant pathogen capable of infecting over 400 host plant species, including high‐value agricultural crops such as cotton, while also being observed to infect agricultural weeds such as Noogoora burr in Australia (Evans, 1971). Verticillium wilt has been monitored in Australian cotton since 1983 with isolates stored in the NSW DPI Plant Pathology and Mycology Herbarium (DAR) reference collection (Chapman et al, 2016). It was originally believed that only one vegetative compatibility group (VCG) was present in Australian cotton, VCG4B; however, discoveries of VCG2A in 2014, VCG1A in 2015 and VCG6 in 2022 have since been made (Bauer et al, 2014; Chapman et al, 2016; Kirkby et al, 2022).…”

“…Verticillium wilt has been monitored in Australian cotton since 1983 with isolates stored in the NSW DPI Plant Pathology and Mycology Herbarium (DAR) reference collection (Chapman et al, 2016). It was originally believed that only one vegetative compatibility group (VCG) was present in Australian cotton, VCG4B; however, discoveries of VCG2A in 2014, VCG1A in 2015 and VCG6 in 2022 have since been made (Bauer et al, 2014; Chapman et al, 2016; Kirkby et al, 2022).…”