Apogee Summary APRES

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Response of the Virginia Market Type Cultivar Bailey to Prohexadione Calcium in North Carolina.

A. COCHRAN*, D. KING, C. ELLISON, D.L. JORDAN, and P.D. JOHNSON, North Carolina Cooperative Extension Service, Raleigh, NC 27695 and M. BALOTA, Tidewater Agricultural Research and Extension Center, Virginia Tech., Suffolk, VA 23437.

The Virginia market type cultivar Bailey has become the dominant cultivar in North Carolina because of high yield potential and resistance to several economically important diseases. This cultivar often produces excessive vine growth that can make digging and vine inversion challenging for farmers. Three experiments were conducted from 2012-2014 to determine response of this cultivar to the plant growth regulator prohexadione calcium (PC) marketed as Apogee. In one experiment from 2012-2014 at Lewiston-Woodville, PC (7.2 oz/acre) was applied at 50% row closure followed by a second application 2 weeks later with peanut dug at weekly intervals beginning in early September through mid-October. In a second experiment from 2013-2014 at Lewiston-Woodville, prohexadione calcium was applied as described previously to peanut planted May 2, May 16-19, and May 28 with four digging dates including September 10 and 24 and October 5 and 20. In a final experiment conducted during 2013 and 2014 (7 site/year combinations), peanut yield following 1, 2, or 3 applications of prohexadione calcium was compared with non-treated peanut with only one digging date. Crop oil concentrate and nitrogen solution were applied with PC. In all experiments PC increased row visibility, with an increase in visibility when the number of applications was increased. However, in the first 2 experiments with multiple digging dates, PC did not affect peanut yield regardless of planting or digging date. In 2 of 7 trials in the experiment with a single digging date, PC increased yield, although response was inconsistent in terms of the number of applications required for the increase in yield. While PC increased row visibility in a consistent manner, yield increases for the cultivar Bailey have been limited. Although not substantiated in these trials or in other research, it is suspected that the generally good plant health due to disease resistance of the cultivar Bailey and the smaller seed size of this cultivar may have minimized benefits of PC in improving pod retention. Historically, cultivars that were larger seeded than Bailey or were more prone to disease often responded more favorably to PC, with improved pod retention suggested as a key mechanism of the increase in yield following PC. Additional research is needed to refute or support this hypothesis.

Article first appeared as North Carolina Peanut Note (PNNC-2015-013)