Estimation of Red Clover Yield Losses Caused by the Clover Root Borer

Reductions in second cutting red clover hay yields caused by the clover root borer, Hylastinus obscurus (Marsham), were estimated by multiple regression analyses. Variables included were number of borers, crown diameter of the root, the square of crown diameter, and foliage weight. Both foliage weight and number of borers per root were found to increase as crown diameter increased, the relationships being curvilinear. Regression of foliage weight on borers, independent of crown diameter, showed an increase in number of borers to result in a decrease in foliage weight. Calculations indicated that an average of 1.5 borers per root resulted in a 5.5 %reduction in yield in Ohio in 1950.