North Carolina State University Raleigh, North Carolina, United States
Abstract Text: Hotwater treatment or thermotherapy has been used for over a century to control plant pathogens in plant parts including roots, bulbs, tubers, seeds, and rootstocks. The focus of this study was to investigate whether thermotherapy may be suitable for treating sweetpotato storage roots to eradicate the guava root-knot nematode, Meloidogyne enterolobii, within the storage roots. Meloidogyne enterolobii is an aggressive nematode that was identified in North Carolina in 2011, the top producer of sweetpotatoes for consumption and propagation in the country. Three preliminary temperatures, 45, 50 and 55°C, and three exposure times 10, 15, and 20 minutes were replicated over 6 M. enterolobii-infected roots per treatment group in a fully crossed experiment. After treatment, groups of roots were split into two, with half air dried and half placed in room temperature water to cool. Effects on nematode survival were evaluated through a greenhouse bioassay. Roots were cut into 2.5 cm pieces, then incorporated into soil placed in a pot, and a tomato bioassay plant potted. At 90 days after setup, tomato plants were destructively harvested and root gall severity rating and eggs per gram of root quantified. Differences among treatment groups were explored using ANOVA and mean separation. While complete control was not observed in the initial experiment, decreased root galling and egg production was observed in the most intensely treated roots. Results of the study will support further investigation of non-chemical management of M. enterolobii in sweetpotato.
