In 2015, an alfalfa research trial was established at the Arlington Agricultural Research Station in Arlington, WI. Two cultivars of alfalfa (DKA44-16RR – Conventional Roundup Ready®; HarvXtra – Reduced-lignin, Roundup Ready ®) were sprayed with seven fungicide treatments and compared to a non-treated control. Yield, quality, and return on investment of the treatments were evaluated under two cutting duration schemes (30-day vs. 40-day) for both cultivars. Results of the entire study can be found at: http://fyi.uwex.edu/fieldcroppathology/files/2015/11/2015-DLS-MFA-FINAL-REPORT.pdf. In the 2015 study (seeding year), both cultivars responded to fungicide in a similar way (second crop specifically). In the 30-day cutting duration, fungicide application resulted in little discernable difference in disease level, defoliation, or quality compared to not treating with fungicide. Return on investment (ROI) calculations indicated that no positive return was achieved if the hay was sold, or was kept on the farm and fed to dairy cows, for the 30-day duration of cut. For the 40-day duration, significant differences in fungicide treatments were identified for disease levels, defoliation, and quality compared to the non-treated controls. These differences resulted in positive ROI (using the Milk 2006 model) for the second crop where the fungicides Headline® and Quadris® were used, under the scenario where hay would be kept on the farm and fed to dairy cows. If hay was sold, no positive ROI was identified for either treatment for this crop.
Soil Science Extension
University of Wisconsin Madison