Preplant Weed Control with Harmony Extra Tank Mixtures

D.B. Reynolds, P.R. Vidrine, D.E. Fairbanks, and J.L. Griffin


Field experiments were conducted in 1993 at Alexandria, Baton Rouge, and St. Joseph, Louisiana to evaluate preplant weed control in stale seedbed cotton (Gossypium hirsutum L.) with combinations of Gramoxone Extra 2.5AS (paraquat) or Roundup D-Pak 6.42AS (glyphosate) with Harmony Extra 75DF (2:1 thifensulfuron + tribenuron). Treatments were evaluated for cutleafeveningprimrose (Oenothera laciniata Hill), Pennsylvania smartweed (Polygonum pensylvanicum L.), barnyardgrass [Echinochloa crus-galli (L.) Beauv.], prickly sida (Sida spinosa L.), and pitted and entireleaf morningglory (Ipomoea lacunosa L. and Ipomoea hederacea var. integriuscula Gay) control. Treatments were arranged factorially in a randomized complete block design with 3 or 4 replications. Roundup D-Pak at 10, 15, and 20 ounces of product/acre (oz pr/A) and Gramoxone Extra at 1.5 and 2.0 pints product/acre (pt/A) were applied alone and with Harmony Extra at 0, 0.25, and 0.50 oz pr/A All treatments were applied in 15 gallons per acre spray volume with a non-ionic surfactant.

Gramoxone Extra or Harmony Extra applied alone controlled cutleaf eveningprimrose no more than 55%. The addition of Harmony Extra at 0.50 oz pr/A to Gramoxone Extra at either rate increased cutleaf eveningprimrose control by 37 and 66%, respectively, 42 days after treatment (DAT). When evaluated 14 and 28 DAT, Harmony Extra at 0.25 oz pr/A increased cutleaf eveningprimrose control by 27 and 20%, respectively, when tank-mixed with Roundup D-Pak 20 oz pr/A but showed no differences 42 DAT. Harmony Extra applied alone gave up to 99% Pennslyvania smartweed control. Addition of Harmony Extra at 0.25 or 0.50 oz pr/A to Roundup D-Pak or Gramoxone Extra increased Pennslyvania smartweed control over that of either herbicide applied alone. When applied alone, Harmony Extra partially controlled barnyardgrass (13-20%), prickly sida (48-56%), and morningglory (67-71%). Harmony Extra did not enhance control of barnyardgrass and prickly sida when tank-mixed with Roundup D-Pak or Gramoxone Extra. Morningglory control was enhanced slightly only when Harmony Extra 0.25 oz pr/A was tank mixed with Roundup D-Pak at 15 oz pr/A.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pg. 1700
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998