Tillage Effect on Population Densities of Heterodera Glycines in the United States: A Review.

Tillage remains a common practice in crop production despite a prevailing trend to reduce tillage operations in many cropping systems. The influence of tillage on the population density of the soybean cyst nematode (SCN, Heterodera glycines) has been widely investigated, but contrasting results have been observed among studies. Thus, whether or not tillage favors SCN population densities remains unclear. In this study, we conducted a quantitative review of tillage effect on SCN population densities based on studies in the U.S. from 1954, when SCN was first found in North Carolina, to 2015. The review emphasizes soil tillage intensity ratings, study location and characteristics, and changes in agronomic management that were considered relevant to the understanding of tillage effect on SCN. Effect size and associated variance were obtained from published studies and are presented as a meta-analysis for descriptive purposes. The results of this ongoing analysis will contribute to a better understanding of the relationship between tillage and SCN.