摘要
Studies were undertaken to explore the relationship of R. stolonifer susceptibility with preharvest growing conditions and postharvest handling of sweetpotatoes. Additional studies were also completed to identify effective decay control products. A three-year study investigated the effect of preharvest conditions on R. stolonifer and Erwinia chrysanthemi susceptibility. Roots were harvested from 75 sweetpotato fields and information collected including soil samples, weather during the growing season, weed density, and insect injury (153 predictors). Roots were inoculated after 100 days in storage. Mean R. stolonifer incidence was 34.9% (standard deviation=31.7%) and mean E. chrysanthemi incidence was 51.0% (standard deviation=30.5%). Predictive models were developed using forward stepwise regression to identify predictors of interest, followed by mixed model analysis (p-valueR. stolonifer susceptibility is best predicted by soil calcium (% CEC), plant-available soil phosphorus, soil humic matter (%), mean air temperature, mean volumetric soil moisture at 40 cm, and mean soil temperature at 2 cm (all over the growing season). E. chrysanthemi susceptibility is best predicted by soil pH and days that soil temperature exceeds 32 oC (14 days pre- harvest). Studies were also conducted to define the relationship between postharvest handling and susceptibility to R. stolonifer . Experiments designed to simulate packingline handling found root ends are more susceptible that mid-sections and that increasing the number of time a root is dropped as well as increasing the impact force resulted in increased decay susceptibility. 'Hernandez' roots were significantly more susceptible than 'Beauregard' in all experiments. To confirm the relationship of impacts and disease development, Beauregard roots were sampled from locations along commercial packinglines. High decay in inoculated as compared to non-inoculated roots indicates that wounding is occurring that could result in disease if the pathogen was present at higher levels. Evaluations of reduced-risk fungicides, bio-fungicides and generally recognized as safe products for efficacy against R. stolonifer found that reduced-risk chemistries boscalid+pyraclostrobin and fludioxonil significantly reduced R. stolonifer development and performed similarly to dicloran. Pseudomonas syringae based products were moderately effective although results were extremely variable among tests. Generally recognized as safe treatments were ineffective by testing methods used.
摘要译文
研究，着手探索R.易感性匍枝穗带的生长条件和sweetpotatoes的采后处理的关系。另外的研究也已完成，以确定有效衰减控制产品。一项为期三年的研究调查对R.和匍枝腐穗易感性条件的影响。根从75甘薯收获领域和信息收集，包括土壤样本，在生长季节的天气，杂草密度和虫伤（153预测）。后存储百天根接种。R.平均匍枝发病率为34.9％，25（标准差= 31.7％25），平均菊E.发生率为51.0％，25（标准差= 30.5％25）。预测模型采用向前逐步回归识别相关预测开发，其次是混合模型分析（对估价师。药敏匍枝是最好的预测土壤钙（25％CEC），植物可用土壤中的磷，土壤腐殖质（25％），平均气温，平均容积土壤湿度在40厘米，平均地温为2厘米（全生长期）。E.菊敏感性是最好的预测土壤pH值和天数，土壤温度超过32摄氏度（14天前收获）。研究还进行了定义对R.匍枝采后处理和易感性之间的关系。设计成模拟packingline处理实验发现根端部更容易受到该中间部分和该增加的时间数的根被丢弃以及增加的冲击力导致增加的衰减的易感性。Hernandez的“根均显著比博勒加德在所有实验中更容易受到影响。为了证实影响和疾病发展的关系，加德根系从沿商业packinglines位置采样。高衰减的接种与未接种的根表示伤人发生可能导致疾病如病原体是存在更高的水平。降低风险的杀真菌剂，生物杀真菌剂，一般认为是安全的产品，为针对R·葡枝功效的评价发现，降低风险的化学啶酰菌胺+唑菌胺酯和咯菌腈显著降低R.匍枝发展并按照相似于氯硝胺。丁香假单胞菌为基础的产品是比较有效，虽然结果中测试变数极大。一般认为安全的治疗是无效的由使用的测试方法。
Edmunds, Brooke Aurora. Factors affecting susceptibility to - and management of - postharvest soft rot of sweetpotatoes caused by Rhizopus stolonifer[D]. US: North Carolina State University, 2008