Antagonistic actinomycete strains isolated from the environment are valuable tools for an eco-friendly, healthy, and safe control of phytopathogenic fungi. We have evaluated the culture filtrate of Streptomyces griseorubens E44G, an actinomycete strain isolated from soil, on the growth and ultrastructure of hyphal cells of the phytopathogenic fungus Fusarium oxysporum f. sp. lycopersici, the causal agent of Fusarium wilt disease of tomato.

Stem canker and black scurf of potato, caused by Rhizoctonia solani, can be serious diseases causing an economically significant damage. Biocontrol activity of Bacillus subtilis ATCC 11774 against the Rhizoctonia diseases of potato was investigated in this study. Chitinase enzyme was optimally produced by B. subtilis under batch fermentation conditions similar to those of the potato-growing soil. The maximum chitinase was obtained at initial pH 8 and 30 °C. In vitro, the lytic action of the B. subtilis chitinase was detected releasing 355 μg GlcNAc ml–1 from the cell wall extract of R.

The antifungal activity of Streptomyces griseorubens E44G against Rhizoctonia solani, the causal agent of root rot disease of corn, was investigated. The mycelial growth of R. solani was inhibited by S. griseorubens E44G, indicating that it has an antifungal potential. The antagonist, S. griseorubens E44G, was detected to have proteolytic activity, using the method of casein hydrolysis. Moreover, the protease production was optimized under submerged conditions.

ABSTRACT Under field production phase, wilt, stalk and tuber rots diseases lead to considerable decline in Jerusalem artichoke (JA) yield and quality, and subsequently reduce storability of tubers. This study aimed to test and prepare suitable formula for increasing yield, quality and storability of JA tubers, through controlling the causative pathogens; Sclerotinia sclerotiorum and Rhizoctonia solani.