Anastomosis group (AG) affinity of pectic isozyme (zymogram) groups (ZG) of Rhizoctonia solani from the Western Australian cereal-belt

Over 4250 isolates of R. solani obtained from the cereal growing belt of Western Australia have been characterized using pectic isozyme patterns (zymograms). With few exceptions, all can be placed in one or other 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 group AG-8 and cause rhizoctonia bare patch disease of cereals, legumes and forage pastures. Another (ZG5) has been identified as AG-2-1. The latter identification is confirmed in this study and the anastomosis group affinity of the remaining five ZGs reported. ZG4 and ZG10 are placed in AG-2-2, ZG6 in AG-2-1 and ZG9 in AG-10. ZG3, although it reacts in 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 as an aid to disease management and as a research tool for identifying sub-groups within AGs is discussed. Integration of the AG and ZG systems, and use of ZGs to subdivide AGs is also discussed.