Scott J C, Gordon T R, Shaw D V, Koike S T
Department of Plant Pathology.
Department of Plant Sciences, University of California, Davis, CA 95616.
Plant Dis. 2010 Jan;94(1):13-17. doi: 10.1094/PDIS-94-1-0013.
The effect of temperature on Fusarium wilt of lettuce (Lactuca sativa), caused by Fusarium oxysporum f. sp. lactucae, was examined in a controlled environment. Nine lettuce cultivars planted in infested potting mix (500 or 5,000 CFU/g) were maintained under high/low diurnal temperature regimes of 26/18°C, 28/20°C, or 33/26°C. Three cultivars were resistant to Fusarium wilt under all test conditions, and thus were little affected by differences in inoculum level or temperature. The remaining cultivars were more susceptible and manifested more severe symptoms at the higher inoculum level and when maintained at higher temperatures. The tendency for the disease to be more severe under warmer conditions may be due, in part, to an effect of temperature on growth of the pathogen. Radial growth rates calculated for six isolates of F. oxysporum f. sp. lactucae were observed to increase from 10°C up to an apparent maximum near 25°C. The results of this study suggest that growers can reduce the risk of damage from Fusarium wilt by avoiding susceptible cultivars during the warmest planting periods. Further, isolates of F. oxysporum f. sp. lactucae were shown to have a distinctive colony morphology in culture, which made it possible to distinguish them from nonpathogenic strains.
在可控环境中研究了温度对由尖孢镰刀菌莴苣专化型（Fusarium oxysporum f. sp. lactucae）引起的莴苣（Lactuca sativa）枯萎病的影响。将种植在受侵染盆栽基质（500或5000 CFU/g）中的9个莴苣品种置于26/18°C、28/20°C或33/26°C的高低日温 regimes 下。三个品种在所有测试条件下均对枯萎病具有抗性，因此接种水平或温度的差异对其影响很小。其余品种更易感，在较高接种水平和较高温度下表现出更严重的症状。在温暖条件下病害更严重的趋势可能部分归因于温度对病原菌生长的影响。观察到尖孢镰刀菌莴苣专化型的六个分离株的径向生长速率从10°C开始增加，直至在接近25°C时达到明显最大值。本研究结果表明，种植者可以通过在最温暖的种植期避免种植易感品种来降低枯萎病造成损害的风险。此外，尖孢镰刀菌莴苣专化型的分离株在培养中表现出独特的菌落形态，这使得能够将它们与非致病菌株区分开来。
