Improving Lima Bean (Phaseolus lunatus) Productivity in the Mid-Atlantic Region

Lima bean (Phaseolus lunatus) is the cornerstone crop of the vegetable processing industry in the Delmarva area of the Mid-Atlantic region with green baby lima beans being planted over 8000 hectares in the area. Productivity of the crop is affected significantly by heat and water stress.  Flower and pod loss can be severe during high temperature periods and split sets are common. Because of these abiotic stress factors, yields have plateaued over the last decade.  The general practice to reduce losses to heat has been to plant the crop to flower and mature in the cooler periods of late summer and early fall.  This limits the amount of weeks that companies can process the crop. Cooler periods also are conducive to several diseases (downy mildew, pod blight, and white mold) that further limit the productivity of the lima beans.  Research on variety improvement, stress mitigation, tillage, multiple cropping, and irrigation is being conducted in an effort to improve lima bean productivity and increase the potential harvest period.  A Delaware-based breeding program has shown yield increases of over 30% compared to currently available varieties with improved yield stability by utilizing heat tolerant materials in crosses; stress mitigation studies have shown increases of 35% with the used of particle films, strobilurin fungicides, and cytokinin applications in combinations; tillage studies are being conducted to determine the potential for reduced tillage in production; multiple cropping studies where the crop is harvested then allowed to regrow for a second harvest have achieved overall yields over 6000 kg/ha and irrigation studies are underway to better understand water needs of the crop.  Preliminary results from this research show great promise for improving overall productivity of lima beans for the eastern U.S. production area.