Shaanxi Kiwi Common Biocontrol Technology And Field Applications

As the main kiwifruit-growing areas, Shaanxi also is a worst-hit area of kiwifruit disease, especially kiwifruit bacterial canker and kiwifruit bacterial leaf blight disease, decreasing not only the yield and quality, but also the whole industrialization of kiwifruit. Because of the overuse of chemical pesticides inevitably led to pesticide residues in fruit and environmental pollution, it is necessary to seek an approach that healthy, green and environment protected, and antagonistic strains is proved to be the most effectively and feasiblely.96 strains were isolated from rhizosphere soil of kiwifruit and other different source, in primary and further screening, strains ZM12 and SF6 revealed obviously antibacterial activities against the pathogen of kiwifruit bacterial canker(Pseudomonas syringae Pv. Actinidiae) and kiwifruit bacterial leaf blight disease(Pseudomonas syringae Pv. Actinidiae). And the two strains also revealed good antagonism to common diseases pathogens of fruits and vagetables, Fusarim axysporium, Erwinia carotovora subsp.carotovora and so on, they are broad-spectrum antagonistic strains.Based on the morphological characteristics and physiological-biochemical characteristics of stains ZM12 and SF6, they are regarded as Bacillus preliminarily, and the analysis of 16S rDNA sequence showed stain ZM12 is Bacillus subtilis, SF6 is Bacillus megaterium.Culture ZM12 and SF6 in one NA plate, it showed normal growth, did not express any antibacterial activities to each other; Do mix culture of ZM12 and SF6 in liquid medium, the viable counts of mixed fermentation broth are evidently more than the other two when strains ZM12 and SF6 were cultured individually, display that mix culture can enhance the growth of strains. In pot experiments, mixed fermentation broth showed excellent control effect to kiwifruit bacterial canker and kiwifruit bacterial leaf blight disease, can reach 92.4% and 93.5% respectively.Field experiment showed that all of the three concentration of mixed antagonistic inoculum have achieved the desirable control efficacy towards kiwifruit diseases. The control effect to kiwifruit bacterial canker were 89.8%,85.6%,83.7%, and spots cure effect were 94.0%,88.0%,86.0%, respectively, the control effect to kiwifruit bacterial leaf blight disease reached to 90.4%,87.0% and 85.9%, significantly higher than those of chemical bactericide 95% CT (p<0.05).The kiwifruit of mixed antagonistic inoculum treatment no pesticide residues, no heavy metals or extra-low than national request, accord with national standard of non-pollution food, and the quality of kiwifruit has been improved. Mixed antagonistic inoculum benefit the growth of kiwifruit tree.