Interaction of Fusarium solani, Macrophomina phaseolina and Rhizoctonia solani as root rot pathogens of Cucumis melo

ABSTRACT Root diseases represent one of the main reasons for yield loss in melon crops, especially root and stem rots caused by pathogens like the fungi Fusarium solani (Fs), Macrophomina phaseolina (Mp) and Rhizoctonia solani (Rs), frequently observed in muskmelon either alone or in combination. The objective of this study was to evaluate the effect of the interaction between the pathogens Fs, Mp and Rs on the incidence and severity of root rot and muskmelon development. Two greenhouse experiments were performed using plastic pots with substrate infested with each pathogenic agent alone or in combination. The second experiment was conducted in the same pots that were used in the first experiment. In the first experiment, the disease incidence was higher for the treatment with Fs alone. In the second experiment, the disease incidence and severity were greater for treatment Fs + Rs than for Fs alone. Macrophomina phaseolina was the most commonly isolated pathogen when applied to the plants in a paired mixed inoculum (Fs + Mp and Mp + Rs) in the first experiment. In the second experiment, Fs was more prevalent than the other studied pathogens. Soil infested with Fs had the lowest fresh weight of muskmelon. The pathogens Fs and Mp were more competitive than Rs.摘要：根部病害是导致甜瓜作物产量损失的主要原因之一，其中由茄病镰孢（Fusarium solani，Fs）、菜豆壳球孢（Macrophomina phaseolina，Mp）和立枯丝核菌（Rhizoctonia solani，Rs）等真菌引发的根茎腐烂病，在甜瓜上常单独或混合发生。本研究旨在探究Fs、Mp与Rs三种病原菌的交互作用对根腐病发病率、病情严重度以及甜瓜生长发育的影响。本研究开展了两次温室盆栽试验，采用接种单一病原菌或混合病原菌的栽培基质填充塑料盆进行栽培。第二次试验沿用第一次试验使用的塑料盆开展。第一次试验中，单一Fs接种处理的根腐病发病率更高。第二次试验中，Fs+Rs混合接种处理的根腐病发病率与病情严重度均显著高于单一Fs接种处理。第一次试验采用成对混合接种体（Fs+Mp与Mp+Rs）接种植株时，分离得到的优势病原菌为菜豆壳球孢（Mp）。第二次试验中，茄病镰孢（Fs）的分离率高于其余供试病原菌。接种Fs的栽培基质栽培的甜瓜鲜重最低。Fs与Mp的竞争能力强于Rs。