The Effect of Clopyralid Rate on Annual Strawberry Production and Black Medic (Medicago lupulina) Control

Clopyralid is registered for control of broadleaf weeds in strawberry.  A recent label permits application when fruit and flowers are present on the plant.  The objective of the study was to evaluate rates of clopyralid in annual strawberry and black medic control.  Clopyralid was applied at 45, 66, 132, 195, and 261 g. a.e./ha.  Treatments were applied with a backpack sprayer with XR11004 nozzles calibrated to deliver the spray solution at 284 L/ha.  At the time of application, strawberry ‘Sonata’ had flowers and fruit present on the plants and the plants were producing new leaves.  Black medic was 15 cm. tall and 23 cm. wide.  No crop injury was observed during the experiment.  Yield was not different among treatments.  Strawberry yielded 99 to 123% of the nontreated control.  At 14 days after treatment (DAT), clopyralid at 45 g./ha. had the lowest black medic control (87%) and was similar to clopyralid at 66 g./ha.  At 27 DAT, clopyralid at 45 g./ha. had the lowest control (79%).  The application of clopyralid may be cultivar specific, however, this cultivar had excellent crop tolerance.  All rates provided excellent control of black medic.  The registered rates provided the least control and the control was greater than acceptable amounts of control.