Biological control of seedling damping-off and root rot of sugar beet plants

Some fungal and bacterial bioagents as well as an Actinomycete isolate were screened for their antagonistic effects against S. rolfsii, R. solani, M. phaseolina, F. oxysporum and F. solani in vitro. Trichoderma hamatum, T. harzianum, T. pseudokningii, certain isolates of Bacillus subtilis and one isolate of Pseudomonas fluorescens were the most effective bioagents in suppressing the radial growth of the four pathogens, in general. Yet, they were less effective in retarding growth of Fusarium spp. as compared with the other pathogens under study. Studying biological control showed the possibility of controlling sugar beet damping-off and root rot by certain bioagents as T. hamatum, T. hazianum, Pseudomonas fluorescens and B. subtilis under greenhouse (S. rolfsii-infested soil) and field (natural infection) conditions. These treatments also caused and increase root yield per plot.

Streptomyces scabrisporus sp. nov.

The taxonomic position was determined for a soil actinomycete, isolate KM-4927T, that produced the antibiotic hitachimycin. The strain was assigned to the genus Streptomyces on the basis of 16S rDNA analysis, where it formed a separate clade. The strain is characterized by grey aerial cell mass, spiral spore chains and a rugose spore surface, menaquinones of the MK-9(H4, H2, H6) types and cell-wall chemotype I. DNA–DNA reassociation with 21 phylogenetically neighbouring Streptomyces type strains showing similar morphological characteristics to strain KM-4927T indicated that this isolate is only moderately related to other Streptomyces species. On the basis of genomic and physiological properties, the novel species Streptomyces scabrisporus sp. nov. is proposed; the type strain is strain KM-4927T (=JCM 11712T=NRRL B-24202T).