Microbial communities in hot pepper (Capsicum annuum L.) cultivation fields under different cultivation methods were investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis. Rhizosphere soil and leaf samples were collected from control, conventional and nature-friendly cultivation fields between May and July, 2009. Two Bacillus subtilis strains were applied to nature-friendly cultivation fields as biocontrol agents during the sampling period. Relative abundances of bacteria and plant pathogenic fungi related T-RFs were also measured to monitor the effect of biocontrol agents on potential plant pathogenic fungi. In the principal component analysis (PCA) based on T-RFLP profiles, the microbial communities from rhizosphere soil samples in July, including bacteria and fungi, showed distinct difference between nature-friendly cultivation fields and other cultivation fields. However, there was no correlation between cultivation methods and leaf microbial communities at any sampling period. Changes in the abundance of bacteria related T-RF in the rhizosphere of nature-friendly cultivation fields were observed clearly two months after application of biocontrol agent, while the abundance of plant pathogenic fungi related T-RFs significantly decreased.

In August 2010, a severe crown rot was observed on chrysanthemum (Chrysanthemum morifolium Ramat., variety Sinro) in several greenhouses located at Damyang and Muan, Jeonnam province, Korea. Three isolates (EML-CHS1, -CHS2, and -CHS3) of Fusarium were isolated from the affected plants and identified based on morphological characteristics and rDNA internal transcribed spacer (ITS) sequence analysis. Sequence analysis by BLAST indicated that EML-CHS1, -CHS2 and CHS3 were closest to a Fusarium species, F. solani with > 99% sequence similarity. Pathogenicity tests were performed on chrysanthemum with spore suspensions containing 3.4 × 10 6 spores/ml using the dipping method. Ten days after inoculation, similar symptoms to those observed in the greenhouses were seen on the inoculated plants. The causal fungus was reisolated from the artificially inoculated basal stems, fulfilling Koch's postulates. To our knowledge, this is the first report of crown rot by Fusarium solani on chrysanthemum (Chrysanthemum morifolium) in Korea.