Epidemiology and chemical control of take-all on seminal and adventitious roots of wheat.
Epidemiology and chemical control of take-all on seminal and adventitious roots of wheat.
复制标题
小麦种子根和不定根全食的流行病学和化学防治。
作者：
D. J. Bailey;N. Paveley;C. Pillinger;J. Foulkes;J. Spink;C. Gilligan
摘要采用流行病学模拟方法，研究了硅硫草胺种子处理对冬小麦全蚀病田间流行的影响。一个简单的间隔模型，包括一次侵染、二次侵染、根生产和接种物腐烂的术语，与从重复田间试验获得的描述每株病根和感根数量随温度时间的变化的数据相匹配。这产生了一条复合曲线，描述了病根比例随时间的变化，单调地增加到最初的平台期，然后在之后呈指数增加。这一曲线的形状与初次感染和继发感染的连续阶段一致。种子处理在疫情的两个阶段都减少了病根的比例。然而，对该模型的分析发现，初次感染率显著下降，但继发性感染率并未下降。通过扩展隔室模型和拟合病和易感的种子或不定根的数量的变化，进一步详细地研究了硅硫草胺影响来自病种或不定根的继发感染的可能性。两种病根来源的二次侵染率均不受影响。种子处理控制了颗粒接种对种子根的初次侵染，但不能控制种子或不定根的继发侵染。在疫情的二次感染阶段之后观察到的用硅硫草胺处理的植物的疾病减少，不是由于化学物质的长期活动，而是由于在流行病早期表现出疾病控制。
ABSTRACT Epidemiological modeling is used to examine the effect of silthiofam seed treatment on field epidemics of take-all in winter wheat. A simple compartmental model, including terms for primary infection, secondary infection, root production, and decay of inoculum, was fitted to data describing change in the number of diseased and susceptible roots per plant over thermal time obtained from replicated field trials. This produced a composite curve describing change in the proportion of diseased roots over time that increased monotonically to an initial plateau and then increased exponentially thereafter. The shape of this curve was consistent with consecutive phases of primary and secondary infection. The seed treatment reduced the proportion of diseased roots throughout both phases of the epidemic. However, analysis with the model detected a significant reduction in the rate of primary, but not secondary, infection. The potential for silthiofam to affect secondary infection from diseased seminal or adventitious roots was examined in further detail by extending the compartmental model and fitting to change in the number of diseased and susceptible seminal or adventitious roots. Rates of secondary infection from either source of infected roots were not affected. Seed treatment controlled primary infection of seminal roots from particulate inoculum but not secondary infection from either seminal or adventitious roots. The reduction in disease for silthiofam-treated plants observed following the secondary infection phase of the epidemic was not due to long-term activity of the chemical but to the manifestation of disease control early in the epidemic.