Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/16/2005
Publication Date: 4/1/2006
Citation: Nyczepir, A.P., Wood, B.W., Reilly, C.C. 2006. Association of meloidogyne partityla with nickel deficiency and mouse-ear of pecan. HortScience. 41:402-404. 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 typical Mouse-ear (ME) symptoms and dead branches in the upper canopy. Both the ME and replant disorders have recently been found to be due to a nickel (Ni) deficiency, with timely foliar application of Ni correcting both disorders. Determining the interrelationship among root parasitism by M. partityla, Ni deficiency, and severity of ME symptoms in pecan in Georgia needs to be investigated. In 2002-05, a field microplot study was conducted to determine the association of the pecan root-knot nematode and ring nematode with nickel deficiency and Mouse-ear of pecan. Results indicate that nickel deficiency, and thus ME symptom, in pecan trees can be triggered and enhanced by M. partityla colonization of roots. These data provide useful insights into the interrelationship between pecan root-knot nematode and severity of ME symptoms in pecan in Georgia and establishes the need to further investigate potential management strategies of this root-knot nematode pest on pecan.
Technical Abstract: Pecan [Carya illinoinensis (Wangenh.) K. Koch] trees exhibit nickel (Ni) deficiency in certain orchard situations. The symptoms are manifest as either “mouse-ear” or “replant” disorder and in certain situations is associated with nematode parasitism. A field microplot study of pecan seedlings treated with Meloidogyne partityla and Criconemoides xenoplax or both found that parasitism by M. partityla can result in enhancement in the severity of mouse-ear symptoms and a reduction in foliar Ni concentration. The Ni threshold for triggering morphological symptoms in young developing foliage was between 0.265 and 0.862 ug.g-1 dw, while the threshold for rosetting was between 0.007 and 0.064 ug.g-1 dw. Results indicate that parasitism by M. partityla, but not C. xenoplax, is a contributing factor to the induction of Ni deficiency in pecan and raises the possibility of nematode parasitism and Ni nutrition being a contributing factor to many plant maladies.