ABSTRACTROW WIDTH AND PLANT POPULATION EFFECTS ON PLANT MORPHOLOGY, WEED CONTROL, AND YIELD IN TYPE II BLACK BEAN AND SMALL RED BEANByRyan Charles Holmes The development of upright black and small red bean varieties gives dry bean growers opportunities to plant in narrower rows, which has been associated with yield and weed control benefits in many crops, and to use direct harvest methods with a standard combine. Field studies were conducted in 2010 and 2011 at two locations in Michigan to examine the effect of row width, population, and herbicide combination on canopy closure, weed suppression, pest management, plant architecture, and yield in two upright varieties, `Zorro' black and `Merlot' small red beans. In one set of studies, each variety was planted in 38- and 76-cm rows, as well as 51-cm rows at one location. Populations were 196500, 262000, and 327000 plants ha-1 in black bean and 148000, 196500, and 262000 plants ha-1 in small red bean. In a second set of studies, `Zorro' only was planted at 262000 plants ha-1 in row widths of 38- and 76-cm, and six weed control strategies were examined: S-metolachlor + halosulfuron (PRE), S-metolachlor (PRE) fb. bentazon + fomesafen (POST), halosulfuron (PRE) + clethodim (+fomesafen in one site-year) (POST), imazamox + bentazon (POST), weed-free, and no weed control. Narrow rows generally increased canopy closure, enhanced weed suppression, did not increase pest pressure, increased branching and pod formation, and increased yield. Population had little effect on canopy closure, weed suppression, pest pressure or yield. Pod formation, seeds per pod, and branching decreased as population increased. All herbicide combinations suppressed weeds and increased yields compared to the untreated but varied in their control of specific weeds.Nomenclature: Dry bean, Phaseolus vulgaris L.; preemergence; postemergence
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