| Replant diseases on strawberry caused by Rhizoctonia solani, Fusarium oxysporum and Verticillium dahliae are serious for the sustainable production of strawberry under continuous cropping. This research assayed the inhibitive effect of calcium cyanamide against pathogenic fungi of replant disease of strawberry on Petri dishes and on sterilized soil.Results indicated that calcium cyanamide had obvious inhibitory effect on three pathogens on PDA plate. Among them, the inhibitive effect on R. solani was the strongest. As the concentrations of calcium cyanamide increased from 0.1 mg/mL to 1 mg/mL, the inhibitive rate on mycelial growth reached from 40.89% to 100%. Inhibitive effect on F. oxysporum and V. dahliae also existed on Petri dishes but with less extent. Micropscope observation showed that the mycelium of the three pathogenic fungi appeared distortion, with protoplasm agglomerated and leaking of cell contents after treated by calcium cyanamide.Similar results were also observed in sterilized soil. When the concentration of calcium cyanamide in sterilized soil was 0.1%, the inhibitory effect on F. oxysporum and V. dahliae reached 68.46% and 54.46%, respectively. In addition, the influences of soil moisture content, temperature and pH value on the inhibitive effect of calcium cyanamide were studied. The results showed that the inhibitive effect of calcium cyanamide could be influenced greatly by moisture content in the soil. The inhibitive effect of calcium cyanamide on F. oxysporum and V. dahliae increased quickly as the soil moisture changed from 10% to 60% for F. oxysporum and from 10% to 40% for V. dahliae. The inhibitive effect of calcium cyanamide became stronger when the temperature was above 35℃. The best of inhibitory efficacy was obtained at pH 6.5-7.5.In this study, calcium cyanamide was applied into the replanting soil of strawberry to examine the influence on microbial community. Results showed that moderate and high concentration of calcium cyanamide dosages had influences on bacteria, fungi and actinomyces. For the moderate concentration treatment, the number of bacteria, fungi and actinomyces reduced to 27.92%, 51.22% and 68.42% comparing to untreated check 1 day after treatment. After 3 days, the number of fungi and bacteria began to rise, and the number of actinomyces rose obviously 7 days after treatment. All of the three types of microbes returned to control level after 15 days.Based on the in vitro test, calcium cyanamide was evaluated for plant growth promotion of strawberries from 2006 to 2007 in the strawberry greenhouse of Mancheng. Calcium cyanamide and soil solarization were applied to sterilize soil 20-30 days before planting. Prior to planting, the roots of strawberry plants were dipped in biological control agent and 3000-fold hymexazol dilutions. Differences were observed between treatment of calcium cyanamide and control of chloropicrin, and calcium cyanamide did not improve the effect of biological control agent. The reason could be that the alkali soil of greenhouse had effect on inhibitory efficacy of calcium cyanamide.
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