The number of herbicides available for use in strawberry (Fragaria×ananassa Duch.) production is limited. Corn gluten hydrolysate (CGH) is a water-soluble extract of corn gluten meal (CGM), a by-product of corn wet-milling. Both CGH and CGM have been shown to inhibit root development of seedlings and can provide nitrogen (N). Four weed control and/or N- containing products were studied: CGH, CGM, urea (46N-0P-0K), and urea applied with DCPA at 8.4 kg·ha-1 a.i. Treatments were applied at N rates of 0, 9.8, 19.5, and 29.3 g·m-2. The 0 g·m-2 of N treatment served as the control. During the 1995 establishment season, all treatments were applied in June, July, and August. Treatments were applied in July and August during the 1996, 1997, and 1998 growing seasons. Dicot and monocot weed number and weed shoot dry weights were determined ≈30 days after both July and August treatments. Strawberry yield data were collected in June. Leaf N data were collected during the first week of July, before renovation. When CGH was applied in July, dicot weed number in August decreased in one of four years, but CGH never affected the number of monocot weeds. CGM application in July, reduced the number of dicot weeds found in plots in Aug. 1995 and 1998. Urea had no effect on dicot weed number from 1995 to 1997. However, in 1998, dicot weed number was reduced by as much as 79% as the rate of urea increased. In all study years, dicot weed number was reduced between 86% and 97%, for the high rate of DCPA + urea, compared with control plots. With few exceptions, rate of N had no effect on leaf N or yield. CGH exhibited limited potential as a natural weed control product; it reduced dicot weed number in one year, but did not affect the number of monocot weeds in any year. Strawberry yield in plots receiving CGH showed a linear increase in one year (1998), but did not show an increase in the other 2 years. Chemical name used: dimethyl tetrachloroterephthalate (DCPA)
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