Recovery of Japanese pear trees from a decline associated with white root rot caused by Rosellinia necatrix was examined after root reinforcement treatment with healthy stocks. Fluazinam alone, which is highly effective against white root rot, could not reverse the decline. However, the declined trees were recovered successfully from the syndrome after application of Fluazinam in combination with the root reinforcement treatment with some healthy stocks.
One hundred and seventeen isolates of Rhizoctonia solani Kühn were obtained from creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw] and Kentucky bluegrass (Poa pratensis L.) with symptoms of brown patch disease on golf courses in Japan from 1997 through 2006. Based on colony morphology and restriction fragment length polymorphism (RFLP) analysis using the internal transcribed spacer region of ribosomal DNA (rDNA-ITS), 96 isolates (82.1%) were identified as R. solani AG-2-2 IIIB, and 21 isolates (18.0%) were R. solani AG-1 IB. On the basis of the results of this report, brown patch on creeping bentgrass is mainly caused by R. solani AG-2-2 IIIB nearly throughout Japan and on Kentucky bluegrass it is caused by R. solani AG-1 IB in the cool weather area in Japan.
A new disease of carrot (Daucus carota L.) caused by Rhizoctonia solani was found in Tokushima Prefecture in 2003 and 2004. Isolates of R. solani were obtained from carrot seedlings with damping-off. Typical damping-off symptoms observed in fields were reproduced on seedlings grown from carrot seeds sown in soil amended with these isolates. The causal agent was identified as R. solani AG-4 HG II by hyphal anastomosis grouping and cultural morphology. We proposed the name of the disease as “seedling damping-off of carrot.”