Submitted to: Nematology
Publication Type: Abstract Only
Publication Acceptance Date: March 19, 2002
Publication Date: June 8, 2002
Citation: Nyczepir, A.P., Reilly, C.C., Wood, B.W., Thomas, S.H. 2002. First report of meloidogyne partityla on pecan in georgia. Nematology. v.4. p.272. 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 known to attack pecan. In 1986, a new root-knot species (M. partityla) was found on pecan in South Africa. Since then this species has only been reported on pecan in Texas and New Mexico. In New Mexico this nematode was associated with stressed pecan trees exhibiting dead branches in the upper canopy. Determining the incidence of this nematode on pecan in the Southeast needs to be investigated. Tree decline was observed in a commercial pecan orchard in central Georgia. Affected trees exhibited symptoms that included dead branches in the upper canopy. Root samples revealed the presence of very small galls with associated egg masses which is typical of root-knot nematode infection. Identification of this nematode was determined by two laboratories; one at USDA Byron, GA and the other at New Mexico State University, Las Cruces. Specimens were identified as M. partityla at both locations. This is the first report of M. partityla in Georgia and the third report in the United States. These data provide useful insights into the need to determine the economic importance and distribution of this root-knot nematode pest on pecan in Georgia and throughout North America.
Technical Abstract: Tree decline was observed in a commercial pecan orchard in Georgia in 2000. Affected trees exhibited dead branches in the upper canopy, stunted growth, and feeder roots with small galls and associated egg masses typical of root-knot nematode infection. All declining trees that were examined had root systems infected with Meloidogyne sp. Identification of this nematode was based on two procedures. First, in Georgia, females were removed from root galls of declining trees and identified by determining the esterase phenotype as compared to standard root-knot nematode species including M. partityla. Secondly, galled roots were sent to New Mexico State University in Las Cruces, where mitochondrial DNA from specimens was extracted and compared to standard root-knot nematode species. Specimens were identified as M. partityla at both locations. This is the first report of M. partityla from Georgia, and the third report of this nematode outside of South Africa. Meloidogyne partityla may be endemic to North America and not South Africa. It is believed that this nematode entered South Africa on pecan rootstock imported from the USA between 1912 and 1940. Determining the distribution of M. partityla within the pecan-growing regions of Georgia and North America is warranted.