Alternative Plant Parasitic Nematode Control with Ultrasonic Sound Waves.

Plant-parasitic nematodes such as the sting (Belonolaimus longicaudatus), sheath (Hemicycliophora spp.), and the ring (Mesocriconema spp.) nematodes can damage turfgrasses in sandy, well-drained soils. In the absence of resistant or tolerant cultivars, management with soil fumigants or nematicides is often the only practical option to reduce nematode populations below damage thresholds. Therefore, laboratory, greenhouse, and field trials to determine how ultrasonic sound waves (20 kHz) affect soil nematode populations were conducted during 2009 and 2010 at the University of Georgia Tifton Campus on ‘TifEagle’ bermudagrasses (Cynodon dactylon × C. transvaalensis). During preliminary laboratory testing, all sting nematodes that were placed into 15 mL glass vials filled with water and subjected to 10 s of ultrasound survived, but all died when exposed to 30 s of ultrasound. Initial trials conducted on samples harvested from a TifEagle green indicated that 60 s exposure to ultrasound resulted in an 89% decrease in the naturally occurring sting nematode populations in the soil, whereas the 30 s treatment had no effect. Further greenhouse testing conducted on TifEagle grown in steam sterilized soil, sting nematode populations were reduced by 80% in conetainers that were inoculated and exposed to 3 m of ultrasound weekly for 6 wk compared to the untreated control. Finally, sting nematode populations were statistically unchanged after 24 d in the control and 1.5 m ultrasound treatment in field plots on a TifEagle green, but were reduced 76% and 87% with 3.0 m of ultrasound and Nemacur, respectively. Further research to study the effects of different wavelengths and methodologies on plant parasitic nematodes in the soil is warranted, especially in areas where restrictions on current chemical treatments are becoming more stringent.