Tillage for Control of Volunteer Proso Millet and for Production of Sorghum1

Abstract

AbstractProduction of proso millet (Panicum miliaceum L.) results in volunteer plants the following year. This research was conducted to determine if primary tillage influences the population density of volunteer proso and the persistence of the volunteer problem in five subsequent crops of sorghum [Sorghum bicolor (L.) Moench]. Following proso harvest, eight tillage treatments were repeated on the same plots for 5 years on Typic Hapludoll soil at Rosemount, MN. Treatments included moldboard or chisel plowing in the fall or spring, rototilling in the spring, moldboard or chisel plowing in the fall followed by rototilling in the spring, and zero tillage. Seed production of proso and other weeds was prevented for 5 and 3 years, respectively. Proso and annual weed numbers ha−1 were determined from repeated counts made shortly after emergence in permanent 1‐m2 quadrats. Most (80%) of the total proso emergence occurred the 1st year after proso harvest, but 17, 2, and 1% occurred in the next 3 years, respectively. Although moldboard plowing gave the most 1st year control, proso was a potential major weed for 4 years following annual moldboard plowing in the fall and for only 3 years following the other tillage treatments. Most proso plants emerged in May, 10% emerged in June, and only 3% later. Moldboard plowing gave the most control of annual weeds other than proso. Highest grain sorghum yields followed moldboard plowing or rototilling in March or April or moldboard plowing in the fall followed by rototilling in April or May.