Isolation trials from strawberry plants showing mainly wilt symptoms grown at Behera, Ismailia,
Menofia, Kalubia and Giza governorates yielded Alternaria spp., F.oxysporum , F.solani, Rhizoctonia solani and
Verticillium dahliae. Pathogenicity test of the five isolates of V.dahliae revealed that they caused wilt symptoms and
Ismailia isolate was the most virulent one. Five isolates of Bacillus spp., i.e. Bacillus coagulans , B.pumilus ,
B.megaterium, B.subtilis and B. thuringiensis and two isolates of Pseudomonas spp., i.e. P. fluorescens and P.putida
were isolated from the rhizospheric soil of apparently healthy strawberry plants grown in a field have severe infection
by Verticillium wilt and screened for their efficacy against V.dahliae, in vitro and in vivo experiments. In general,
P.fluorescens followed by Bacillus subtilis were the most efficient in reducing the linear growth of the pathogenic
fungus. Culture filtrate of B.subtilis and P.fluorescens as well as the aqueous filtrate of compost resulted in significant
reduction to the germinated conidiospores of the causal fungus compared with the control . This reduction was
gradually increased by increasing the tested concentration. In addition, culture filtrate of the compost was more efficient
than the culture filtrate of the tested bioagents. The combination among compost, the bioagents B.subtilis and
P.fluorescens and soil solarization resulted in significant reduction to strawberry Verticillium wilt with significant
increase to the produced fruits and their total soluble solids (T.S.S.) , either each of them was used alone or in their
different combinations, compared with the control treatment (infested with the causal fungus). On the other hand, soil
solarization was the most efficient in this regard compared with the other two items of disease management when
each of them was used alone. Moreover, no apparent infection was detected when the bioagents B.subtilis and
P.fluorescens ,compost and soil solarization were used together and the produced fruit yield and it´s T.S.S. were , to
somewhat, similar to the control treatment (uninfested soil with any fungus). |
