Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2004
Publication Date: September 1, 2004
Citation: Nyczepir, A.P., Reilly, C.C., Wood, B.W. 2004. Incidence and association of Meloidogyne partityla with mouse-ear disorders of pecan in Georgia [abstract]. Journal of Nematology. 2004. 36(3):338. Interpretive Summary: Pecan is an important nut crop throughout much of the southern United States with Georgia being ranked as the leading producer. Root-knot nematodes, Meloidogyne spp., are recognized as pests of pecan. In 2002, the pecan root-knot nematode, M. partityla, was first reported on pecan in Georgia and was associated with stressed trees exhibiting dead branches in the upper canopy. Determining the distribution and association of this nematode with mouse-ear disorders in pecan in Georgia needs to be investigated. In 2003-04, a survey was conducted in the major pecan growing regions of Georgia to determine distribution of M. partityla and other root-knot nematodes. Additionally, the relationship between this nematode alone and in combination with a ring nematode on incidence of mouse-ear was investigated. Results indicate that M. partityla was the dominant root-knot nematode on pecan in Georgia and that it was involved with predisposing pecan to mouse-ear disorder. These data provide useful insights into the occurrence of M. partityla on pecan throughout Georgia's pecan production areas and of its association with mouse-ear development
Technical Abstract: The pecan root-knot nematode, Meloidogyne partityla (Mp), has been associated with pecan trees exhibiting above-ground symptoms that included dead branches in the upper canopy, severely stunted growth, and (or) mouse-ear leaf symptoms. In 2003-04, a survey was conducted in the major pecan growing regions of Georgia to determine distribution of Mp and other Meloidogyne spp. Root samples infested with Meloidogyne spp. were obtained from 13 different pecan production sites. Female nematodes were teased from fresh root galls of declining trees and identified by determining the esterase phenotype from replicate samples of single females as compared to standard root-knot nematode species. and two unknown Meloidogyne spp. were the only root-knot nematode species found parasitizing pecan. Meloidogyne partityla was found in a greater number of samples and appears to be the dominant root-knot nematode species in pecan. In July 2002, the relationship between Mp alone and in combination with Mesocriconema xenoplax (Mx) on incidence of mouse-ear (ME) was initiated in field microplots. The occurrence of ME symptoms was detected at bud break on foliage in April 2003, nine months after inoculation. Trees were rated for ME leaflet deformity and severity. The ME severity index consisted of a 1-to-10 scale, with 1 = no ME leaflet symptoms and 10 = >50% leaf distortion and multiple stunted shoots. Trees growing in Mp-infested soil alone (8.3) and Mp + Mx infested soil (7.6) exhibited greater (P < 0.05) ME symptoms than in the uninoculated control (4.6) plots. No differences in degree of ME severity occurred between Mx-infested soil alone (5.9) and the uninoculated control plots.