Integration of biocontrol agents and thermotherapy to control Fusarium fujikuroi on rice seeds

Abstract: Fusarium fujikuroi, the causal agent of bakanae disease, is the most important seedborne fungal pathogen of rice. Chemical alternatives to seed treatments against bakanae disease consist in biological and physical control methods. Four yeast isolates were selected among all potential antagonists obtained from various rice seeds on the basis of in vitro and in vivo assays. Two of them were identified as Metschnikowia pulcherrima, one as Pichia guilliermondii and one as Sporidiobolus pararoseus. Biocontrol efficacy of P. guilliermondii and M. pulcherrima on F. fujikuroi was higher in comparison with some applied commercial biofungicides. The seed dressing with antagonistic yeasts diminished the bakanae disease index to 70% compared to control seeds. Biocontrol yeasts resulted even more efficient when combined with thermotherapy, decreasing the disease index less than 5%, and ameliorating the seed germination as well. Selected biocontrol agents could be efficient alternative method to control F. fujikuroi on rice seeds, particularly when combined with thermotherapy.