Distribution and Abundance of Heterodera glycines and Macrophomina phaseolina in Ohio

Abstract

Soybean and corn are grown on more than 60% of the arable land in Ohio. The soybean cyst nematode (SCN) is responsible for significant losses incurred by soybean growers every year. The fungus that causes charcoal rot, Macrophomina phaseolina, causes significant yield loss in soybeans worldwide and can also affect corn. Both organisms are soil-borne pathogens. The objective of this study was to determine the presence, distribution, and abundance of both SCN and M. phaseolina in soybean and corn fields across Ohio. During 2013 and 2014, composite soil samples were collected from 370 corn and soybean fields. Samples were processed for SCN eggs/100 cm3 and M. phaseolina colony forming units (CFU)/g soil with standard techniques. Results from this study revealed a widespread distribution of SCN and M. phaseolina in both soybean and corn fields. This study represents the first survey on the distribution of M. phaseolina in Ohio and the findings will be used to educate producers on the potential risks posed by both SCN and M. phaseolina. Accepted for publication 19 February 2016. Published 3 March 2016.

Comparison of Two Soil Sampling Methods for Estimating Population Densities of Heterodera glycines Cysts

“…Soybean cyst nematode (SCN) was first reported in soybean fields in Ohio in 1987 (Riedel and Golden 1988), and by the mid 1990s, SCN was found in 73% of the soybean acreage within the state (Wilson et al 1996). In a recent survey of 143 soybean fields, 81.8% were positive for SCN; only 6 of the 143 soybean fields sampled had population densities exceeding an economic threshold of greater than 2,000 eggs/100 cm 3 soil (Lopez-Nicora et al 2016). However, a large number of individual fields in the state do have very high population densities of SCN (Dorrance and Niblack, unpublished data) and some populations in the region have adapted to the most widely deployed resistance derived from PI88788 (Niblack, unpublished data;.…”