Biological control of some garlic diseases using antagonistic fungi and bacteria

Résumé

Eight Trichoderma isolates which isolated from rhizospher of garlic plant and one isolte T. asperellum was obtained on PDA medium, from the commercial product (Biocontrol T34).  Also eleven isolates of rhizobacteria namly; B. subtilis, two isolates (Bs1 and Bs2), B.megaterium two isolates (Bm1and Bm2), P. fluorescens two isolates (Pf1 and Pf2), four isolates A. chroococcum (Az1, Az2, Az3 and Az4) and Penibacillus polymyxa one isolate  were tested in vitro to study thir ability against S. ceprivorum , F. oxysporum f. sp. cepae  and P. terrestris which caused white rot, basal rot and pink rot of garlic plants, respectively. The results showed that Trichoderma isolate number (T3) gave the highest reduction on maycelial growth of three pathogenic fungi, which adentified as Trichoderma harzianum, followed T. asperellum (T34), then isolate (T5) and isolate (T7). which adentified as Trichoderma harzianum and Trichoderma hamatum, respectively. Pseudomonas. fluorescens isolate (Pf1), followed by P. fluorescens (Pf2),  B. subtilis (Bs2), A. chroococcum (Az4)  and B. subtilis  (Bs1), then  A. chroococcum (Az2), B. megaterium (Bm2) and Penibacillus polymyxa  gave highly antagonistic effect was clear against the tested fungi respectively. A pot experiment was crried out under greenhouse conditions to evaluate the efficacy of commercial biofungicides biozeid , Bio-Arc, Plant Guard, T34 biocontrol and Rhizo-N, and biofertilizers Nitrobien, phosphoren, Biogen, Potassiumag, Ascobein and carialin were evaluated individually against garlic white rot, basal rot and pink rot diseases. Data showed that treated soil with biofungicides and biofertilizers reduced white rot, basal rot and pink rot diseases compared with the control. Treated soil with Rhizo-N, T34 biocontrol, Phosphoren and Nitrobien gave the best reduction of disease severity throughout two successive growing seasons.