Distribution of Heterodera glycines in Paraguay and its effect on the growth of soybean

Abstract

Heterodera glycines was identified from a total of 13 fields in the main soybean producing areas of Paraguay in a 2004-2005 survey. Among these fields, eight, three and two were located in the districts of Canindeyu, Alto Parana and Caaguazu, respectively, and seven of them are new records of the nematode in the country. Severe growth reduction of soybean was observed in a field at San Alberto, Alto Parana, where the average height of soybean plants was less than 60% of that of apparently nondamaged plants. The infestation by nematode females of root systems of stunted plants was severe compared to the light infestation of roots in the surrounding area. An average of 28,000 eggs per 100 g of soil was found in the rhizosphere of the stunted area. Results suggest that H. glycines is potentially a serious threat to soybean production in Paraguay.