Management of root and crown-rot of strawberry by Bacillus Bioagents, Bion (BTH) and vermicompost in Libya

Abstract

Many fungal isolates i.e., Fusarium spp., F.solani , Macrophomina phaseolina  the pycnidial state of Sclrotium bataticola) , the fungus like Phytophthora cactorum, Rhizoctonia  solani  the imperfect state of Thanatephorus cucumeris),  Sclerotinia sclerotiorum and Sclerotium rolfsii ( the sclerotial state of Athelia rolfsii) were isolated from strawberry roots existing mainly root  and crown -rot symptoms collected from different fields at Tagoraa,Trablus, Libya. The pathogenicity of these isolates manifested that they all caused root and crown-rot symptoms. M.phaseolina and R.solani were the most pathogenic ones. Six Bacillus bioagents i.e., were isolated from the rhizospheric soil of strawberry plants apparently free from root and crown-rot infection. These bacteria were evaluated for their antagonistic capability for M.phaseolina isolate-3 and  R.solani isolate-2 both in vitro and in vivo.  Both B.subtilis and B. thuringiensis exerted the highest  antagonism  against  the linear growth of both pathogenic fungi. Sterilized tea filtrate of the tested vermicompost caused significant inhibition to the linear growth of the tested two pathogenic fungi in comparison with control treatment. This inhibition of both B.subtilis , B. thuringiensis and vermicompost was gradually increased significantly by increasing their concentration. The combination among the bioagents B.subtilis and B. thuringiensis ,the inducer resistance elicitor Bion (BTH) and Vermicompost significantly reduced strawberry root and-crown-rot with significant increase to the produced fruits  yield and their total soluble solids (T.S.S.) , when each of them was used alone or in their different combinations, compared with control treatment . Furthermore, vermicompost was the most efficient treatment in this respect in comparison with the other three items of disease management. Moreover, no apparent infection (dead plants) was detected when B.subtilis , B. thuringiensis , BTH  and vermicompost were used together, which resulted in producing the highest fruit yield  of  high T.S.S., firmness and total ascorbic acid (vitamin-c),  to somewhat, nearly similar to control treatment ( un-infested soil with the any of  the causal fungi).