Anastomosis groups and pathogenicity of Rhizoctonia diseased plants. Each isolate was hyphalsolani isolates from Brazil. Plant Disease 69:599-601. tipped and conformed to the current species concept of R. solani (15). Anastomosis groups (AG) of 130 Rhizoctonia solani isolates obtained from 31 plant species found Throughout the study, all isolates were in I I states of Brazil were determined. Fifty-nine isolates were assigned to AG-4, 10 to AG-3, 42 to maintained on potato-dextrose agar AG-2, and 11 to AG-i. Eight isolates did not anastomose with any of the tester strains or among (PDA) slants at 10 ± 1 C and transferred themselves, and no isolate was assigned to AG-5. Pathogenicity of 35 isolates from different p d a lly t f0 me dium. anastomosis groups on hypocotyls and/or leaves of kidney bean, soybean, red pepper, radish, periodically to fresh medium. sugar beet, and cabbage varied considerably, from nonvirulent to highly virulent. In general, The isolates were subjected to hyphal anastomosis groups lacked host specificity. The optimum growth temperature for isolates tested anastomosis pairing by using the tester varied from 20 to 30 C.

Viable cells of Clavibacter michiganensis subsp. michiganensis (CMM), the causal agent of bacterial canker of tomato, were discriminated from the dead cells by quantitative real-time polymerase chain reaction (PCR), after the bacterial solution was treated with the DNA binding dye ethidium monoazide (EMA). The primers and TaqMan probe, based on the 16S-23S rDNA spacer sequences, were highly specific for CMM at the subspecies level. The detection limit of the direct real-time PCR was 10 3 colony forming units per mL (cfu mL -1 ) in samples and with an apparent sensitivity of 2 cfu of target cells in PCR reaction solution. Application of this method allows for selective quantification of viable cells of CMM and facilitates monitoring the pathogen in tomato seeds.

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