Submitted to: Journal of Nematology
Publication Type: Abstract only
Publication Acceptance Date: 7/11/2005
Publication Date: 9/1/2005
Citation: Nyczepir, A.P., Reilly, C.C., Wood, B.W. 2005. Nematode interactions on peach and pecan [abstract]. Journal of Nematology. 37:386. Interpretive Summary: Peach and pecan are important fruit and nut crops throughout much of the southern United States with Georgia being ranked #3 & #2, respectively. Ring (Mesocriconema xenoplax), root-knot (Meloidogyne spp.) and root-lesion (Pratylenchus vulnus) nematodes are recognized as important pests of peach and (or) pecan. Determining the interaction of these nematodes with regard to peach tree short life (PTSL) disease complex and mouse-ear disorders in pecan in Georgia needs to be investigated. Three individual long-term field microplot studies were conducted at ARS Byron, GA to determine the interaction among the ring, root-knot, and (or) root-lesion nematodes as it relates to PTSL tree death in peach and mouse-ear disorders in pecan. Results indicate that ring nematode alone was solely responsible for making peach trees more susceptible to PTSL tree death and the root-knot nematode (M. partityla) was responsible for making pecan trees more susceptible to mouse-ear leaf disorder. These data provide useful insights into the interactive relationships among nematode pests in peach and pecan disease complexes and in developing appropriate nematode management strategies.
Technical Abstract: The association of peach-tree-short-life (PTSL) with old peach land has led to the hypothesis that some predisposing factors persist in old orchard sites that make new trees more susceptible to cold injury, bacterial canker Pseudomonas syringae or both. It has been demonstrated that old sites are not a prerequisite for PTSL to occur and that the presence of Mesocriconema xenoplax is a critical biotic component for PTSL development. Recent results indicate that PTSL development in subsequent peach orchards was dependent upon the cumulative population exposure of trees to M. xenoplax. In the real world, however, M. xenoplax is not the only nematode pest present in peach orchards in the southeastern United States. Other pests include Meloidogyne spp. and Pratylenchus vulnus. The question that arises is the interactive role these other nematodes have with M. xenoplax in predisposing trees to PTSL. In two separate field microplot studies with M. xenoplax, evidence indicates that no trees growing in either M. incognita or P. vulnus infested soil died from PTSL. However, tree growth was reduced more in the presence of M. xenoplax + M. incognita than either of these nematodes alone. In pecan, the interaction between M. xenoplax and M. partityla was suspected in trees exhibiting above-ground symptoms that included dead branches in the upper canopy, stunted growth, and (or) mouse-ear leaf symptoms. In a field microplot study, trees growing in M. partityla and M. partityla + M. xenoplax infested soil exhibited greater mouse-ear symptoms than in the uninoculated plots. Understanding the interaction between nematode pests and their associated disease complex is important in developing the appropriate nematode management strategy.