ANASTOMOSIS GROUP (AG) AFFINITY OF PECTIC ISOZYME (ZYMOGRAM) GROUPS (ZG) OF RHIZOCTONIA-SOLANI FROM THE WESTERN-AUSTRALIAN CEREAL-BELT

Over 4250 isolates of X. solani obtained from the cereal growing belt of Western Australia have been characterized using pectic isozyme patt erns (zymograms). With few exceptions, all can be placed in one or oth er of 10 zymogram groups (ZG), four of which (ZG1-1, ZG1-2, ZG1-4, and ZG1-5) have previously been identified as members of anastomosis grou p AG-8 and cause rhizoctonia bare patch disease of cereals, legumes an d forage pastures. Another (ZG5) has been identified as AG-2-1. The la tter identification is confirmed in this study and the anastomosis gro up affinity of the remaining five ZGs reported. ZG4 and ZG10 are place d in AG-2-2, ZG6 in AG-2-1 and ZG9 in AG-10. ZG3, although it reacts i n a very limited way with some isolates of AG-2-1 and AG-8, appears to represent an as yet unreported AG. The potential value of zymograms a s an aid to disease management and as a research tool for identifying sub-groups within AGs is discussed. Integration of the AG and ZG syste ms, and use of ZGs to subdivide AGs is also discussed.