Control Efficacy Of Rotation And Bio-fumigation Against Strawberry Replant Diseases

Replant disease is a restrict factor for the development of strawberry industry.In order to control the replant diseases of strawberry,the cabbage-lettuce rotation was tested in field of Mancheng(Hebei province) during 2007 and 2009.Pot trials were also made in greenhouse.The main results were as follows:1.Disease index of strawberry root after cabbage-lettuce rotation had no significant difference with chloropicrin treatment in field and pot trials,while much less than those of replanting treantments.2.The plant height,plant width,number of leaves and stem diameter were measured for the fumigation,replanting and rotation treatments in field of Mancheng.Results showed that comparing with replanting treatment,the rotation treatment promoted the plant growth significantly(p＜0.05).The rotation treatment was at the same statistical level of chloropicrin treatment.3.The quality and the yields of strawberry were tested.The results showed that rotation treatment could increase the yield and improve the fruit quality.Compared with replanting treatment,rotation treatment increased the yield by 40.31%,Vc of fruit by 10.67%;the soluble solid by 2.46%;total acid content by 11.11%;and the sensory quality by 29.69%.The fruit quality level of rotation treatment had no difference with chloropicrin treatment.4.The control effect of soil-fumigation with the cabbage leaf at dosage 3.5 kg/m~2 was measured 20 days after plastic film mulching.The results showed that the amount of fungi of the biofumigation with cabbage treatment decreased 1.80 times and 1.46 times in field and in pot trial respectively compared with the replanting treatment.The number of bacterium of the bio-fumigationin increased 1.24 times and 3.06 times.5.The root exudates and the extract of cabbage have a significant suppression on mycelium growth of 3 kind pathogens.The inhibition rates to Verticillium spp.were 44.65%,37.5%,to Rhizoctonia spp.were 45.75%,38.14%and to Fusarium spp.were 48.33%,22.81%respectively.The root exudates of cabbage had a significant suppression on conidium germination,the inhibition rates to Verticillium spp and Fusarium spp were 35.55%and 42.66%respectively.But the extract of cabbage had no suppression on conidium germination.6.The population of microbes in soil,rhizosphere and root surface were affected by strawberry rotation.The rotation treatment had lower fungi population compared to strawberry replanting.In the replanting treatment of field,the gross amount of fungi in rhizosphere and root surface was more than rotation treatment.The gross amounts of bacterium and actinomycetes in replanting treatment were less than rotation treatment.The result shows that soils with crop rotation decreased plant mortality rate and had lower fungi population.7.According to pot trial,the cabbage-lettuce rotation treatment with the cabbage leaf had lower fungi population and higher bacterium and actinomycetes compared to without the cabbage leaf rotation treatment.Compared with strawberry replanting,the two rotation treatments had lower fungi population and higher bacterium and actinomycetes populations.8.The different treatments of soil microorganism were isolated by plate dilution method.Four species of pathogenic fungi and 15 species bacterium were purified and identified.The average appearing frequency of Fusarium oxysporum was the highest in the main pathogenic fungi.The appearing frequency of gram-negative bacteria were 73%and 93.3%of the bacteria were rod shaped.