In relation to 6 anastomosis groups in
Rhizoctonia solani (
Thanatephorus cucumeris), effect of temperatures on mycelial growth, hyphal widths, numbers of nucleus and colonial appearances were studied comparatively.
Most isolates belonging to the group AG-1 grew rapidly at 28°C, but slightly at 35°C. Among 6 groups they grew most rapidly (about 30mm/day) at their optimum temperatures. The tissue of sclerotium was compact. The group AG-1 includes
Corticium sasakii and
C. microsclerotia. Most isolates of the group AG-2 grew rapidly at 23-25°C, but not at 33°C. On the mycelial colonies of the isolates small reddish-brown sclerotia were formed in concentric zones. Most isolates of the group AG-3 grew well at lower temperature as AG-2. Their hyphal widths were largest in 6 groups. Most of this group were isolated from potatoes. Isolates of the group AG-4 were able to grow at 35°C. Their hyphal widths were narrowest in contrast to AG-3. This group is the “praticola type” and their cultural colonies are mealy. Most isolates of the group AG-5 were from soils and their macroscopic appearances were yellowish. Most of the group-AG-6 were isolates from sugar beet and soils to which sugar beets had been cultivated. Their mycelial colonies were dark-brown in color, and the tissue of sclerotium was loose.
AG-1, AG-2, AG-3, and AG-4 correspond with I, II, III, and IV of Schultz, A, D, F, and C of Richter and Schneider, AG-1, AG-2, AG-3 and AG-4 of Parmeter
et al., and sasakii type and web-blight type, winter crops type, potato type, and praticola type of Watanabe and Matsuda, respectively. AG-5 perhaps corresponds with B of Richter and Schneider. AG-6 corresponds with rush type and root rot type of Watanabe and Matsuda.
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