Preliminary findings on the grapevine yield response to Brassica biofumigation soil

Young vine decline in the Riverina has been associated with Ilyonectria spp. (grapevine black-foot disease agents) and Botryosphaeriaceae infections of rootstock cuttings and contaminated nursery soil. Ilyonectria soil inoculum builds up with repeated planting. As a recent New Zealand study showed that incorporation into soil of Brassica biofumigation products may reduce this inoculum, we initiated a trial with five replicates of eightunder-vine treatments: 1) control; 2) 2t/ha mustard seed meal; 3) 4t/ha mustard seed meal; 4) 4t/ha 'deactivated' mustard seed meal (with negligible glucosinolates); 5) Benomyl fungicide (positive control); 6) inter-row BQ mustard plants slashed, side thrown and buried atflowering; 7) 2t/ha canola seed meal; and 8) 4t/ha rate canola seed meal. The grapevines were 6-year-old Pinot Noir/Ramsey infected with Ilyonectria spp. and Botryosphaeriaceae.After one season, three treatments significantly increased the number of bunches producedby diseased grapevines: fungicide (+36%); 4t/ha deactivated mustard seed (+32%); and 4t/ha active mustard seed meal (+26%). Two treatments increased the total yield from diseased grapevine: deactivated and active mustard seed meals (+51% and +61% respectively). Wecould thus conclude that 4t/ha mustard seed meal, with and without glucosinolates, significantly improved the growth and yield parameters when buried under diseasedgrapevines. The beneficial effects of deactivated seed meal may be explained by increased rhizosphere beneficial microbial populations but further investigation is required to test this hypothesis. In season two we will replace BQ mustard with Caliente 199 mustard andinvestigate the efficacy of Trichoderma and Streptomyces biological control products in soil applications