SCREENING AND APPLICATION OF EFFECTIVE AGENTS FOR CONTROLLING SWEET POTATO SOFT ROT DISEASE

Sweet potato soft rot, caused by Rhizopus stolonifer, is a major post-harvest fungal disease. The disease is often common in sweet potato production, which can cause sweet potato rot, reduce sweet potato quality and cause huge economic losses. At present, the chemical fungicides commonly used in production to prevent and control sweet potato soft rot have a general effect on the prevention and control of soft rot, and are easy to cause pollution to the environment, which does not meet the development needs of green agriculture. Plant essential oils have been confirmed to have broad-spectrum inhibitory activity, combined with their low toxicity and environmentally friendly characteristics, which has attracted widespread attention from scholars. Exploring the combination of new and efficient plant-derived fungicides and chemical pesticides is a new and effective way to prevent and control sweet potato soft rot. In this paper, R. stolonifer was used to investigate the inhibitory effects of 16 chemical fungicides and 9 essential oils and their complex paired with R. stolonifer. The results are as follows: 1. In order to clarify the control effect of the existing main common fungicides on soft rot in sweet potato, 16 common fungicides were determined by mycelial growth rate method (Tebuconazole, fludioxonil, procymidone, fluazinam, pyrazoxystrobin, prochloraz, kresoxim-methyl, azoxystrobin, prothionazole, octreotide, boscalid, difenoconazole, thifluzamide, carbendazim, pyraclostrobin, and triadimenol).The bacteriostatic activity of Rhizopus creeping was the best inhibitory effect of three fungicides, fluazinam, fludioxonile and tebuconazole, and EC50 were 6.418 ug mL, 2.509 ug/mL and 692 ug mL, respectively.2. In order to clarify the prevention and control effect of plant essential oils on sweet potato soft rot, nine essential oils were determined by essential oil fumigation (Oranges, citronella, garlic, stone calamus, sweet orange, mugwort leaf, sandalwood, artemisia annua, and cedar).The inhibitory effect on Rhizopus creeps, among which the inhibition rate of calamus and orange essential oil was as high as 91%.3. In order to clarify the optimal combination of fungicide and plant essential oil, the indoor control effect of the combination of fludioxonile and calamus essential oil on soft rot in sweet potato was determined by fungus cake inoculation, and the combination of fludioxonile and calamus essential oil could reduce the infection of sweet potato by Rhizopus creeps.In summary, this experiment provides