Effect of heat or chemical disinfection on the viability of ‘Fuji’ apple graft wood
Bundles of dormant wood were submerged in water (45?C for 45 min or 50?C for 15 min), or were wrapped in moist cloth, placed inside zip-locked bags and submerged for 3—6 h or treated with one of three GRAS chemicals or untreated (two bundles per treatment). Scion wood was grafted onto ‘M9’ rootstocks then planted in a randomised order, with growth assessed after 16 weeks. Two of the GRAS treatments and submersion at 45?C for either 45 min or 3 h in a bag did not significantly affect viability compared with the untreated control (83—95% viable). Submersion at 50?C for 15 min reduced viability significantly (70%). Scions did not survive exposure to 50?C for 3—5 h in bags (P<0.001). No significant differences in mean scion shoot length were observed between the untreated wood (107 cm) and that submerged in 45?C water for 45 min, 3 h in a bag, or GRAS-treated. Wood treated at 45?C for 5—6 h in a bag or at 50?C for 15 min had significantly shorter shoots (54—75 cm, P<0.001). Dormant ‘Fuji’ wood remained viable after treatments known to eliminate pathogens from wood.