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TECHNICAL SESSION: Population diversity of plant pathogenic nematodes

Comparing Populations of Plant-Parasitic Nematodes in a Corn-Soybean Rotation in Ohio
Abasola Simon - The Ohio State University. Pierce Paul- The Ohio State University, Rory Lewandowski- Ohio State University, Terry Niblack- The Ohio State University

Corn-soybean rotation is very common in several Midwestern US states, but little is known about the effect of this practice on vermiform plant-parasitic nematode (PPN) communities. In 2016, a commercial field in Wayne County, Ohio with a history of PPNs was planted to corn and the following year to soybean. Soil samples were collected between 16 and 67 days after planting (DAP) at 10 cm increments to a depth of 70 cm. Total PPN population was higher under corn at all sampling intervals. Both Shannon and Simpson's diversity indices were significantly higher in corn at the 0-10 cm depth compared to soybean. The vertical distribution of three PPNs species was also examined. Pratylenchus crenatus predominantly inhabited the upper 40 cm and occurred at significantly higher densities between 42 and 54 DAP, particularly in the root fraction for corn. In soybean, P. crenatus predominantly inhabited the upper 30 cm and occurred at significantly higher densities at 34 DAP, particularly in the soil mineral fraction. The highest population densities of Helicotylenchus pseudorobustus were found in the upper 10 cm in soybean and in the top 40 cm in corn. For Paratylenchus neoamblycephalus, population densities were highest in the upper 20 cm for both corn and soybean. Our results showed that PPN populations varied with sampling depth, growth stage, and crop, suggesting that these factors should be taken into consideration when developing a sampling protocol for vermiform PPN.