Preliminary Studies On The Control Technology Of Pseudomonas Chlororaphis Strain G5 For Fusarium Wilt Of Bitter Gourd And Cucumber

Fusarium wilt of Cucurbitaceae is a kind of vascular disease.Huge economic loss has been caused by Fusarium wilt for production of Cucurbitaceae crop and controlling is very difficult.Pseudomonas chlororaphis strain G5 is an endophytic bacterium with biocontrol function.the P.chlororaphis strain G5 served as biocontrol agent,the biological control technology of bitter gourd and cucumber fusarium wilt have been preliminary investigated.The results are as follows:1.P.chlororaphis strain G5 was obvious antifungal activity against F.oxysporum f.sp.momordicae strain SG-15 and F.oxysporum f.sp.cucumerinum strain FOC through the plate confrontation test.Using different inoculation methods,the strain G5 was able to inhibit mycelia growth of strain SG-15 and reach more than 60%;In the two confrontation method test,78.39% of mycelia growth of strain FOC was inhibited by strain G5.2.Control trials of bitter gourd wilt in pot have been conducted by strain G5.The control effect of bitter gourd wilt reached 31.23% by strain G5.The control effect of Fusarium wilt of cucumber reached 72.88% in cucumber seedlings treated with strain G5.3.The cucumber seeds were treated with strain G5.The length of cucumber seeds radical was measured after 48 hours.Compared with the control treatment,the promoting effect was up to 37.36%.The germinated cucumber seeds were treated again by strain G5.Plant height,stem diameter,leaf area,dry weight,fresh weight and index of seedling quality were more than that of the control treatment after sowing 40 days.Moreover,strain G5 treatment was able to increase the chlorophyll a,chlorophyll b and chlorophyll content of cucumber leaves by 1.6%,4.8%and 1.1%,respectively.4.Test of promoting growth of bitter gourd seedlings was conducted using strain G5 mixed with seaweed fertilizer.Plant height,stem diameter,leaf area,dry weight,fresh weight leaf number and seedling index of bitter gourd seedling were more than the control treatment in three treatments such as single seaweed fertilizer,single application of biocontrol bacteria,biocontrol bacteria mixed with seaweed fertilizer.And when biocontrol bacteria and seaweed fertilizer used in the mixture,the result reached the best effect.5.Three treatments such as seaweed fertilizer applied alone,single application of biocontrol bacteria,seaweed fertilizer mixed with biocontrol bacteria played a certain role in production increase of bitter gourd in the field.The best one among three methods was strain G5 mixed with seaweed fertilizer,and the production was significantly higher than that of control treatment,the yield increase rate reached 43.70%.6.Different dilution ratio of hymexazol inhibited mycelia growth of F.oxysporum f.sp.Momordicae.As dilution ratio increased,the inhibitory effect decreased.The diameter of pathogen colony was measured in the plates including hymexazol with different dilution ratio.The virulence regression equation was obtained for y= 1.9926 + 5.0178 x,and the correlation coefficient was 0.9915.Control efficiency of strain G5 mixed with hymexazol was much better than that of single using chemical or biological agents in greenhouse.Among them,control effect of bitter gourd wilt reached 84.82% by strain G5 mixed with hymexazol,while the control effect of cucumber wilt reached 90.16% by strain G5 mixed with hymexazol.