Meloidogyne Spp. Identification and Distribution in Alabama Crops Via the Differential-Host Test and Molecular Analysis

Three different techniques were performed to determine their efficacy for species identification of Meloidogyne spp. (root-knot nematode, RKN).  These techniques were morphological measurements, the differential-host test, and molecular analysis.  These were initially used on a known greenhouse population of Meloidogyne incognita race 3 that had previously been identified by the differential-host test.  Initial results showed a confirmation of species with the differential-host test and PCR amplification, but morphological measurements of juveniles did not distinguish the test population from M. arenaria and M. javanica.  With the success of species identification, statewide collection began for RKN species identification in Alabama.  Seventy-five samples from 14 counties in Alabama were collected from grower’s fields.  Molecular analysis (PCR) and the differential-host test were used for species identification.  Primer sets IncK-14F/IncK-14R (M. incognita specific) and Far/Rar (M. arenaria specific) were the most robust primer sets used, and were able to identify all 75 samples to species level.    Of these samples, 73 were identified as M. incognita (97%), and two were identified as M. arenaria (3%).  Overall, M. incognita is the most prevalent species of RKN that has been found on cropping systems in Alabama during this project.