Assessment of rhizobacteria from grapevine for their suppressive effect on the parasitic nematode Xiphinema index

The capacity of rhizobacteria isolated from grape plants to protect grapevine roots from damage by the nematode Xiphinema index was assessed in trials carried out in the growing season 2008–2009 and 2009–2010. A total of two groups of bacteria were evaluated, one comprising 49 isolates, of which 37 were assessed in previous studies, and one comprising 90 isolates not previously evaluated. Two assays were performed on the first group, one per season, and one on the second group, lasting two growing seasons. Pots of field soil (3 L) planted with two-month old Thompson Seedless vines were inoculated with 200 or 400 specimens of X. index after inoculation with 106 cfu/ml of test rhizobacteria; the posts were maintained in a shaded greenhouse. Seven isolates from the first group of bacteria (Bacillus brevis, Bacillus megaterium, Cytophaga johnsonae, Pseudomonas fluorescens, Rahnella aquatilis and Stenotrophomonas maltophilia) were effective in decreasing damage in both of the assays (P < 0.05). Ten isolates from the second group (Variovorax paradoxus, Pseudomonas pseudoalcaligenes, Bacillus mycoides, Bacillus sphaericus, Bacillus thuringiensis, Curtobacterium flaccumfaciens, Pseudomonas putida, Pseudomonas alcaligenes and Pseudomonas viridiflava) resulted in the lowest number of galls per gram root. B. brevis and B. megaterium also demonstrated good activity in previous studies on grape plants and are thus promising candidates for further research.

► Rhizobacteria isolated from grapevine plants were assessed in potted grapevines. ► Bacteria-inoculated roots were inoculated with the nematode Xiphinema index. ► 17 isolates were able to reduce damages. ► Species of genera Bacillus and Pseudomonas were the most effective. ► Rahnella aquatilis and Stenotrophomonas maltophilia were also effective.