| Gansu province is the dominant producing area of apple production in the Loess Plateau,and it is also a big province of apple production in the north.But in recent years,with the adjustment of industrial structure and the expansion of planting area,apple valsa canker is widespread and spread constantly in apple producing areas.It has become a threat to the safety,health and sustainability of apple industry in our province and the main constraints of development.The disease is caused by the pathogen of Valsa Mali Miyabe & Yamada,which can infect the phloem and xylem of the host and is difficult to control by chemical control and the conventional fungicides are not effective.In addition,the existing apple tree varieties are easily infected by the pathogen,so the disease can not be controlled by breeding for disease resistance.In view of the problem of reducing the environmental pollution caused by the treatment of fungicides,biological control can be considered as the most desirable and efficient treatment according to the sustainable agricultural development principle.Among them,Bacillus has been widely favored in recent years,because bacillus has the strongest adaptability to the ecological conditions and is widely distributed as a dominant species in soil.This research get the disease apple tree branch sample from Gansu province Zhenyuan county.Through the tissue separation,branches in vitro inoculation method to separate and identificate of pathogenic bacteria.And do the biological control experiment with the bacillus seperated from the hexi corridor.Through the bacteriostatic experiment screening the bacillus which has a strong inhibition activity to apple valsa canker.And makes further research on it,striving to find a new way of the prevention and control of apple valsa canker.The main results list follows:(1)The pathogenic fungi of apple valsa canker was obtained by tissue separation and branches in vitro inoculation,and Valsa Mali was identified by culture characteristics,microscopic morphology and r DNA-ITS sequence analysis.(2)To get the strong antibacterial activity strain to apple valsa canker.The tablet confrontation,inhibition of mycelial growth methods had been used.The finally result of screeing from 289 bacillus which isolated from hexi corridor is that 21 strainsamong that have inhibitory action to apple valsa canker.Which calculated as7.27%,and with the mycelial growth methods 1 of them have a good activity.(3)Combing the morphology,culture characteristics,physiological and biochemical characteristics and 16 S r DNA gene sequence to identify the theories of system development of the strain 7-2-1-2,preliminaryly identificate the strains 7-2-1-2as Bacillus subtilis subsp.spizizenii.(4)The further study of strain 7-2-1-2 showed that the bacteria could enter the logarithmic growth phase only in 2 hours under the conditions of 28 ℃、150 r/min and1% inoculation.The bacteriostasis broad-spectrum determination results showed that the bacteria had better bacteriostasis effect on 4 pathogenic fungi,and the inhibition rate of the pathogen was more than 60%.(5)The biocontrol effect of the metabolites of strain 7-2-1-2 on the Valsa Mali found that the inhibition rate decreased with the increase of the dilution multiple of the filtrate.The effect of strain 7-2-1-2 on the detached branches showed that the lesion area of the isolated branch of the original solution was about 93.53% and the strain 7-2-1-2 filtrate of different dilution multiple had different degree of inhibition on the Valsa Mali. |
