Submitted to: Journal of Applied Seed Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/1997
Publication Date: N/A
Citation: Interpretive Summary: Kentucky bluegrass and rough bluegrass are grown as perennial seed crops in regions of Oregon, Washington, and Idaho. Both species are widely used in golf courses and lawns. However, mixtures or blends of seeds of these two species are not used because of their dissimilar growth habit and color. Further, Kentucky bluegrass seed produced for sod production must usually be free of any contamination of rough bluegrass. Unintentional mixing can occur as a result of field contamination, contamination from harvest equipment, transport, or seed conditioning equipment. Even a small percentage of mixing can be the grounds for reduced seed lot value, rejection, or possible litigation. The objective of this research was to identify woven wire screens that would aid in producing seed lots with reduced levels of noncrop bluegrass. Seed samples from several species were individually placed on each screen and shaken using a screen shaker for 1 minute at 10 Hz and 0.325 inch amplitude. The weights of the sample fraction held on the screen top surface and the fraction passing through each screen were recorded for each cultivar and each screen opening type and size. From these results, it was determined which screen size made the best separation for all species.
Technical Abstract: Woven wire screens for separating Kentucky bluegrass from rough bluegrass seed were tested and the most effective square and rectangular-opening screens identified. The most effective separations overall, where the largest percentage of the crop species was saved and the highest amount of contaminant was removed, resulted from screening with a square, 30x30 woven wire screen or a rectangular, 6x28 woven wire screen. However, these results varied for some of the mixtures tested. Cultivars of these species differed in ease of separation because of size differences within each species.