First Report of Meloidogyne marylandi Infecting Bermudagrass in Oklahoma

Meloidogyne marylandi is a nematode commonly associated with turfgrasses and has been reported to occur in Texas and Arkansas (1,3). In the fall of 2013, a stand of ultradwarf bermudagrass (Cynodon dactylon × C. transvaalensis) plants in a sand-based, research putting green in Stillwater, Oklahoma, exhibited symptoms of decline. Roots of the affected plants had small galls and upon staining of the root system, numerous egg masses were evident. Egg masses were collected, placed in water, and the morphology of 20 hatched, second-stage juveniles were examined. The characteristics of the juveniles were: body length averaged 393.1 ± 19.87 (range: 361 to 425) μm, mean width averaged 16.6 ± 0.7 (15.6 to 17.8) μm, stylet lengths averaged 12.1 ± 0.7 (10.4 to 12.9) μm, dorsal gland orifice from stylet base averaged 2.9 ± 0.4 (2.5 to 3.6) μm, tail lengths averaged 53.7 ± 3.8 (46.2 to 60.4) μm, and the hyaline region of the tails averaged 10.4 ± 1.1 (8.4 to 12.7) μm. Genomic DNA was extracted from six females that were removed from roots. Amplification and sequencing of the mitochondrial DNA region between COII and 16S rRNA genes was performed with primers 1RNAF (5'-TACCTTTGACCAATCACGCT-3') and CO11R (5'-GGTCAATGTTCAGAAATTTGTGG-3') as previously described (2). A PCR product approximately 510 bp in length was obtained and sequenced at the Oklahoma State University Core Facility. Sequences were compared with those in NCBI's nucleotide database using BLAST and had 97% identity with two sequences from M. marylandi (KC473862.1 and KC473863.1) and the next most similar species being M. graminis (JN241898.1) with 83% identity. To our knowledge, this is the first report of the root-knot nematode M. marylandi in Oklahoma. As bermudagrass becomes more commonly used for putting greens in the turfgrass transition zone, M. marylandi may become a more common and damaging pathogen in the region. References: (1) A. A. Elmi et al. Grass For. Sci. 55:166, 2000. (2) M. A. McClure et al. Plant Dis. 96:635, 2012. (3) J. L. Starr et al. Nematrop. 37:43, 2007.