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United States Department of Agriculture

Agricultural Research Service

Title: Pecan Root-knot Nematode, Friend or Foe of Pecan Production

Author
item Nyczepir, Andrew

Submitted to: Pecan Grower
Publication Type: Trade Journal
Publication Acceptance Date: March 17, 2007
Publication Date: May 1, 2007
Citation: Nyczepir, A.P. 2007. Pecan Root-knot Nematode, Friend or Foe of Pecan Production. Pecan Grower. 18(4):38-41.

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. Summarizing the nematode’s current distribution, association with physiological disorders and nutritional deficiencies in pecan, and current management practices needs to be reported. In 2007, a review article for The Pecan Grower was written to summarize current research findings on the pecan root-knot nematode on pecan in the USA over the last 5 years (2002-07). This nematode pest is now 1) known to occur in 6 states, 2) is associated with enhancing the severity of mouse-ear symptoms, and thus Ni deficiency, in pecan trees, and 3) unfortunately no rootstock resistance or biocontrol agents have been successful in suppressing nematode populations over time. These data provide useful insights into the importance of this new nematode to the pecan industry as it relates to mouse-ear development & nickel deficiency, its occurrence throughout Georgia=s production areas, and lack of a suitable management strategy for controlling this nematode pest.

Technical Abstract: The pecan root knot nematode, Meloidogyne partityla, 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 (ME) 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. Meloidogyne partityla 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. This nematode is known to occur on pecan in TX, NM, GA, AZ, OK, & FL. Current research at ARS-Byron has demonstrated that severity of ME symptoms, and thus Ni deficiency, in pecan trees can potentially be triggered or enhanced by parasitism of roots by M. partityla. We have therefore concluded that the pecan root-knot nematode is a pest to the Georgia pecan industry. Furthermore, the need to investigate potential management strategies of M. partityla on pecan is warranted. Since 2002-present, no suitable chemical, rootstock resistance, or biological control agent has been effective in suppressing pecan root-knot nematode populations. The search for a nonchemical pest management strategy for the pecan root-knot nematode, M. partityla, is ongoing.

Last Modified: 11/28/2014
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