The thin, binucleate Rhizoctonia causing Eradu patch is widespread in lupin and cereal crops in Western Australia

Abstract

Eradu patch is a relatively newly discovered disease causing distinct patches in narrow-leaf lupin and ill-thrift patches in barley. Because the field symptoms are similar to Rhizoctonia bare patch and the pathogen, a thin, binucleate Rhizoctonia (TBR), is difficult to isolate, it has been impractical to conduct incidence surveys. The development of a PCR assay specific to TBR allowed field surveys to be conducted in the Western Australian cereal belt in 1999 and 2000. In 1999, 142 lupin crops were surveyed. Of these, 74 were classified visually as healthy and were not sampled. The remaining 68 showed various symptoms of poor growth. TBR was detected in 64 of the 68 crops. In 2000, 297 crops (including lupin, barley, wheat and oats) were surveyed. TBR was detected in 110 of these crops. These surveys demonstrated that the pathogen was widespread and could be detected in lupin, barley, wheat and oats. In contrast to barley, there was no evidence that TBR was causing clear symptoms of ill-thrift patches in wheat or oats.