Submitted to: Pacific Northwest Vegetable Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2004
Publication Date: 11/18/2004
Citation: Boydston, R.A., Spellman, D.E., Williams, M. 2004. Managing wild proso millet and volunteer potatoes in sweet corn. Pacific Northwest Vegetable Association Proceedings, Pasco, WA. pp 35-41.
Technical Abstract: Wild proso millet and volunteer potato are serious weed problems in sweet corn grown in the Columbia Basin of Washington. Wild proso millet seed shatters readily from the inflorescence and adheres to harvested sweet corn ears during processing, thereby lowering processing efficiency and increasing processing cost in order to remove it. Volunteer potatoes can reduce yield of rotation crops and harbor insects, diseases, and nematodes that can infest potato crops. Studies were conducted to evaluate several management strategies of wild proso millet and volunteer potato in sweet corn. The suppressive ability of three sweet corn hybrids differing in canopy architecture on wild proso millet was determined at Prosser, WA and Urbana, IL. Sweet corn hybrids 'WH2801' and 'GH2547' had taller, more fully developed crop canopy (25 to 58% greater per plant leaf area) than 'Spirit and intercepted more light late in the season. All three sweet corn hybrids suppressed wild proso millet growth, although 'WH2801' and 'GH2547' reduced shoot biomass to a greater extent than 'Spirit'. Greatest differences in crop tolerance to wild proso millet among hybrids were observed in IL, where the crop was less vigorous and wild proso millet grew well. In general, yield of 'GH2547' and 'WH2801' was less affected by wild proso millet than 'Spirit'. Initial results suggest selection of crop cultivars may be a useful tool in elevating the crop's ability to tolerate and suppress weed populations in sweet corn. Five preemergence applied herbicide treatments suppressed wild proso millet emergence and growth at six weeks after treatment in sweet corn. More grass weeds emerged in late July and early August in alachlor and EPTC treated plots compared to EPTC plus dimethenamid-p, dimethenamid-p alone, or EPTC plus alachlor. Mesotrione applied alone at rates of 0.06 or 0.09 lb ai/a postemergence controlled potatoes greater than 95% at 2 weeks after treatment and reduced new tuber production by 95% or more in sweet corn. Atrazine applied alone at rates of 0.25 to 1 lb ai/a postemergence controlled potatoes from 21 to 70%. Applying atrazine with mesotrione did not improve volunteer potato control compared to mesotrione alone. Fluroxypyr, dicamba, and dicamba plus diflufenzopyr reduced volunteer potato tuber weight more than tuber number. All treatments containing mesotrione reduced the number of new tubers produced more than fluroxypyr, dicamba, or dicamba plus diflufenzopyr. The potential of mesotrione to reduce the number of new tubers produced coupled with the reduced fitness of plants emerging from those tubers could greatly improve management of volunteer potatoes in the succeeding crop.