Biocontrol Effect Of Rimidori Bacterial Manure Against Apple Valsa Canker

Apple valsa canker is one of the most destructive apple diseases in China. Apple valsa canker control relies on scraping the lesions and smearing chemical fungicide. High toxic fungicides such as asomate is still be used in some orchards though it has been banned in China. In recent years, people pay more attention to apple quality, and fruit safety caused by the pollution and residual of chemical pesticides. We choose Rimidori, a popularly used bacterial manure by the farmers in China as experimental material, and we tried to estimate its application value for apple Valsa canker control. The experiments including scraping the lesions, smearing bacterial sludge and root fertilizing bacterial manure. The results are as follows:1. We applied Rimidori bacterial sludge to cover the Valsa canker wounds, results showed that control effects of the Rimidori bacterial sludge treatments(volume ratio of Rimidori and clay were 1:3 and 1:4) were 100% three months after treatment. It was the same with the fungicide control Thiophanate-methyl ? Naphthylacetate, while the control effect of the clay sludge treatment was 66.7%. The widths of callus were measured 100 days after treatment, the average callus widths of the Rimidori bacterial sludge treatments were 17.3mm(1:3) and 17.0 mm(1:4) seperately, and compared with CK the healing rates were 251.63% and 245.52% respectively. The average callus width the clay treatment was 13.6 mm, and the healing rate was 176.42%. While the average callus width of the Thiophanate-methyl ? Naphthylacetate treatment was 7.8 mm, and the healing rate was 58.54%. The recurrence rate of untreated control(CK) reached 80% when checked 11 months after treatment, while no recurrence was found at the two Rimidori bacterial sludge treatemtns, the control effects reached 100%. The control effect of Rimidori bacterial sludge treatemtns were significantly higher than chemical control of Thiophanate-methyl ? Naphthylacetate(87.5%) and only clay sludge treatment(75%). No recurrence was found two years after treatment when applied Rimidori bacteria sludge.2. Root fertilization experiments were applied, and the results showed that Rimidori bacterial manure can improve apple tree resistance against Valsa canker. When root fertilize Rimidori bacterial manure, the disease incidence was 60.42%, decreased 12.50% and 16.67% separately compared with that of the root fertilizing compound fertilizer and untreated control. The soluble solids content, hardness, acidity of fruit were improved when root fertilized with Rimidori bacterial manure, the qualified rates of acidity, firmness and soluble solids increased 6.67% compare with the untreated control, and there is no significant difference with the compound fertilizer treatment.3. The nutrient elements content in soil and in apple leaves were analysed for the root fertilizing experiments two and half months and five months after treatment seperately. Results showed that the soluble potassium in soil and in leaves increased 0.8 g/kg and 1.13g/kg compare with the compound fertilizer and untreated control, when root fertilized with Rimidori bacterial manure. There was no significant difference of magnesium(Mg) content between Rimidori bacterial manure and compound fertilizer treatment, while the Mg content in untreated control was 0.27 g /kg less than that of the Rimidori treatment. Iron(Fe) element content in soil and apple leaves of Rimidori treatment was significantly higher than that of untreated control, and the Fe content were 24.36mg/kg and 68.67mg/kg higher than compound fertilizer and untreated control respectively. When root fertilized with Rimidori, the content of soil available potassium and organic matter increased 37 mg/kg and 2.75 g/kg separately 5 months after treatment compare with that of untreated control.4. Root fertilized with Rimidori bacterial manurer and combined with Rimidori bacterial sludge to cure the canker lesions of Valsa canker in Akesu of Xinjiang autonomous region. Results showed that positive cure rates ranged from 85% to 100%, and all the wounds cured and formed callus in the experimental orchards, the average width of callus was more than 15 mm. Fifteen of eighteen tested orchard reported significant improvement with the apple tree vigor compare with the previous year, and seventeen of eighteen tested orchards choose to use Rimidori bacterial manure to control apple valsa canker in the next year.