Row width, population density, and harvest date effects on marketable yield of table beet

To maximize the yield of desirable grades of beet roots for processing, 'Ruby Queen' beet (Beta vulgaris) plants were grown at four row widths (18, 20, 22, and 24 inches) and two population densities (25 and 35 plants/ft) within the row in 2006. A third density (15 plants/ft) was added to the 18- and 20-inch row-width treatments in 2007. Beet plants were hand harvested 80, 100, and 120 days after planting, and the roots were graded by size and were weighed. A large number of seedlings died between the time of the initial stand counts 14 to 20 days after planting and the first harvest. Greater seedling loss at higher plant densities within rows was attributed in part to an increased incidence of wirestem disease (Rhizoctonia solani). The percentage of seedlings that produced marketable roots was less at higher seeding rates even though there were more total roots. Harvest date and plant population significantly affected root size and yield, whereas row width had no effect. High seeding rates and fewer days to harvest significantly increased the yield of undersize (<3/4 inches in diameter) roots, while at the same time decreased the yield of oversize roots (>2 1/2 inches in diameter). The highest yield of premium size 1 roots (3/4 inch to <1 5/8 inches in diameter) was obtained with the 35 plants/ft population. While the number of size 1 roots did not increase over the harvest period, the fresh weight per foot of row was significantly higher at 100 or 120 days compared with 80 days. In contrast, the number and fresh weight of larger size 2 roots (1 5/8 to <2 1/2 inches in diameter)/ft of row was highest at 25 plants/ft and did increase with number of days to harvest. The highest marketable yield (sizes 1 and 2 roots) increased significantly with number of days to harvest and was 1.6 to 1.8 tons/acre higher with 25 plants/ft compared with 35 plants/ft. High seeding rates and narrower row spacing increased the cost of seeds per acre and the risk for wirestem and other beet diseases, but did not improve yields in this study.