Identification of Fungal Pathogen Causing Pink Rot of Muskmelons and Inhibitory Effects of Three Chemicals on the Fungal Pathogen in Vitro

In order to identify the fungal pathogen causing pink rot, the muskmelon fruit (cv. Yujingxiang) of natural pink rot was used as the material, and the pathogen was isolated and purified by the method of tissue isolation and single spore isolation respectively. The rDNA-ITS were cloned and sequenced, then BLAST analyzed, finally a phylogenetic tree was constructed. Combined with morphological characteristics, the pathogen was identified as Trichothecium roseum. Furthermore, the inhibition rate of mycelial extension and spore germination, virulence regression equation, concentration for 50% of maximal effect (EC₅₀) and minimum inhibitory concentration (MIC) were examined to compare the inhibitory effection T. roseum in vitro among three chemicals of potassium silicate, carvacrol and lauric acid. The results showed that the inhibition rates of mycelium expansum were 65.94%, 68.60% and 80.41%, and the EC₅₀ of them were 1.39, 0.71 and 0.90 g/L, respectively, when the concentrations of three chemicals were 2.00, 0.08 and 0.16 g/L, respectively. Moreover, the spore germination inhibition rate of T. roseum were 61.24%, 70.04% and 77.53%, EC₅₀ were 1.25, 0.05 and 0.09 g/L, respectively. In addition, the MIC of three chemicals were 1.50, 0.08 and 0.12 g/L, respectively. All these results suggest that potassium silicate, carvacrol and lauric acid can inhibit T. roseum in vitro and they have the potential to control pink rot in muskmelon fruit.