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A Meta-Analytical Approach Towards Optimizing Peanut Digging Decisions in the Presence of Late or Early Leaf Spot Defoliation

Daniel Anco: Clemson University

<div>Late and early leaf spot, respectively caused by <em>Cercosporidium personatum </em>and<em> Cercospora arachidicola</em>, are damaging diseases of peanut (<em>Arachis hypogaea</em>) capable of defoliating canopies and reducing yield. While these diseases each may be more predominant in a given area, both are important on a global scale. To better guide management decisions and quantify relationships of end-of-season defoliation and yield loss, a series of meta-analyses was conducted over more than 80 data sets meeting established criteria. Linear slopes of proportion yield loss with increasing defoliation were estimated separately for runner- and Virginia-type varieties. Results for runner-types indicated yield loss to increase 1.3 to 2.8% per 10% increase in defoliation. Yield loss for Virginia-types was at the rate of 1.6 to 3.2% per corresponding 10% increase, with meta-regression indicating this slope to increase as a function of mean defoliation by approximately 4.0% per 10% increase in defoliation. A second meta-analysis estimated the rate of relative yield increase towards a relative optimum from digging dates within 21 days of optimal relative yield to be 0.7 to 1.4% per day. A third meta-analysis estimated the rate of defoliation progress from related data sets according to the logistic function at 0.094/day. The integration of these findings should help inform recommendations regarding digging under varying defoliation pressures and peanut maturities in order to minimize losses.</div>