Submitted to: National and Southeast Peach Convention Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 9, 2004
Publication Date: January 11, 2004
Citation: Nyczepir, A.P., Shapiro Ilan, D.I., Lewis, E.E. 2004. Observations on the use of entomopathogenic nematodes for suppressing ring nematode, mesocriconema xenoplax, on peach and pecan. National and Southeast Peach Convention Proceedings. p.21. Interpretive Summary: Ring nematodes are widely distributed throughout the world with certain species considered to be economically important to the stone fruit industry. Probably the most studied ring nematode species on Prunus is Mesocriconema xenoplax. It has also been found on pecan in Georgia. This ring nematode is the only plant-parasitic nematode that has been associated with the peach tree short life (PTSL) disease complex in the southeastern United States. Tree loss due to PTSL in South Carolina alone has been estimated at over $5 million per year. New alternatives to chemical control that are less hazardous to man and also more environmentally safe must be found to protect peach trees from this ring nematode. Entomopathogenic nematodes have been reported to suppress the populations of certain root-knot and ring nematode species. However, nothing is known about the efficacy of these nematodes on the ring nematode that attacks peach. In greenhouse and microplot studies, two entomopathogenic nematodes were evaluated for their potential effect on lowering the population density of the ring nematode on peach and pecan over time. In both studies, the ring nematode population was not suppressed in the presence of both entomopathogenic nematodes. These data provide useful insights into the use of entomopathogenic nematodes as an alternative to chemical control of the ring nematode on PTSL sites in the Southeast.
Technical Abstract: The effect of Steinernema riobrave (Sr) and Heterorhabditis bacteriophora (Hb) on population density of Mesocriconema xenoplax (Mx) in peach was studied in the greenhouse. Treatments included: i) Mx alone; ii) Mx + Sr; iii) Mx + Hb; and iv) an uninoculated control. Twenty-one days after adding 112 Mx adults and juveniles/1,500 cm3 soil to the soil surface of each pot, 50 infective juveniles (IJ)/cm2 soil surface of either Sr or Hb were applied. Another application of the same density of Hb or Sr was administered three months later. The study was terminated 180 days following Mx inoculation. The experiment was repeated once with minor modifications which included a Pi of 2,000 Mx/pot and 75 IJ of Sr or Hb/cm2 soil surface. Results from both tests indicate that Mx populations were not suppressed in the presence of either Hb or Sr. In test 2, the presence of Mx alone, Mx+Sr and Mx+Hb caused a reduction in plant growth compared to the uninoculated control. On pecan, 200 Sr IJ/cm2 were applied to the soil surface of 2-year old established Mx populations in microplots. Additional applications of Sr were administered two and four months later. This study was terminated 150 days following the initial application of Sr. The Mx population was not suppressed in the presence of Sr. Based on these findings, use of Sr or Hb is not a feasible alternative to chemical control of Mx.