Studies On Screening And Control Effect Of The Antagonistic Strains Against Tobacco Wilt And Black Shank

The soilborne plant disease is one of the fatal disease in tobacco production, in which the tobacco Pseudomonas solanacearum and black shank is the most serious problem.In order to prevent and control these disease,massive researches have been conducted,domestic and abroad,including chemical and biological control, cultivating disease-resistant variety as well as planting management measure and so on,but they all didn't get a gratifying effect fundamentally,due to their respective limitation In this article,,the microorganism was separated based on ecology principle from plant disease home position soil screens which has antagonistic effect microorganism to the pathogenic germs,and used to make ecology organically fertilizer to prevent and cure the soilborne plant disease.The fertilizer chould improve and renovate soil ecological environment,reduce the chemical fertilizer and the agricultural chemicals use,improve the leaf quality and achieve sustainable development of the leaf tobacco production.The antagonistic strains of tobacco Pseudomonas solanacearum and black shank were screened.6 antagonistic strains of tobacco wilt and 8 antagonistic fungi of tobacco black shank were obtained,and their fermentation condition and effects of field experimentation were tudied.The results were as follows:1.The pathogenic bacteria of tobacco Granville wilt were isolated from the disease trains in tobacco plants from Fuijian Province tobacco field.After isolation and purification,40 trains of soil bacteria were obtained from the same tobacco field,and 6 kinds of the soil strains,named T1 to T6,were identified having obviously antagonistic effect on pathogenic bacteria of Granville wilt by plating culture method. Among the six strains,the antagonistic zone of T5,being about 10.2 to 21.4 mm,was the best.2.The experiment of fermentative cultural condition of the antagonistic strains indicated that the bacterial growth temperature for T5 were 20～40℃,the optimum temperature was 35℃,the logarithm time of growth was 4～24h,pH ranged 5.0～9.0. the optimum culture medium volume was 120ml in 250ml flask in the same inoculation level when the liquid bacteria was produced.The orthogonal test showed that the optimum compositions of liquid culture medium were sucrose(15g/L), compost manure(200g/L)peptone(4g/L),beef power(1.5g/L).3.Some pathogen molds were separated and authenticated from black shank sooty mold stub from science and technology education garden area of Henan Agricultural College,and 13 Soil fundus were separated from the home position soil,8 stub of which had Antagonism to phytophthora parasitica var.nicotianae.They were signed Ty1 to Ty8 respectively.Type Ty3,Ty4 and Ty7 were selected because of a good antagonistic effect without the mutual anti-function.It was found that the antagonistic effect was enhanced after being mixed.4.The study of the fermentation condition of y3,Ty4 and Ty7 showed that three fungus strains chould reach the jarless time of growth after 4-6 days in liquid culture medium,growing very well in temperature 10-45℃.The optimum temperature was 20-35℃.The optimum pH for grown of three fungus strains was very wide from pH4.0 to pH9.0 being good for the strain growth.They are aerobes.The more culture medium volume was,the less hypha of units was.The orthogonal test showed that the optimum compositions of liquid culture medium were sucrose 10g/L,compost manure 200g/L peptone 0.5g/L,yeast 15g/L.5.Field investigation of antagonistic strains preparation indicated that the growth of tobacco is accord with the check,i.e.the antagonistic strains and their biological reagent couldn't give bad effect on the growth of tobacco.The disease ratio and index of Pseudomonas solanacearum and black shank was controlled at some degree by biological reagent in Guangxi.The impact of resistance of Pseudomonas solanacearum was:reduction of the tobacco disease ratio being 8.9 and 39.6 percent one and two times in pouring biological reagent into soil according to the check and reduction ofthe disease index of tobacco being 4 and 38.At the same time,the black shank ratio reduced 0.4 and 2.8 percent,while the disease index of tobacco reduced 2.70 and 4.32.In addition,the effect of the ecological organic fertilizer was studied on tobacco at Shaowu city,Fujian province from 2005 to 2006.The result was showed the fertilizer effect is not good in 2005.The disease control ratio was 1.07 to 3.22 percent,whereas the disease index reduced 0.54 and 2.15.However,the effect gained very advance in 2006.The disease curing ratio reduced 30.69 to 39.58 percent,and the disease index reduced 21.85 and 25.74.The treatment B was best.6.The yield and value of flue-cured tobacco could be improved using the ecological organic fertilizer,base fertilizer.In the best threatment,the yield was improved 252.90 kg/hm~2,with the value being 2619.90 yuan/hm~2 as well as proportion of good and middling tobacco being 0.36%according to comparison treatment.7.the total sugar,improve sugar and starch amount were increasede using the ecological organic fertilizer,while the total N,nicotine and protein amount of tobacco leaves were reduced.So application of the ecological organic fertilizer was benefit for improving the quality of flue-cured tobacco.