WATERMELON HERBICIDE STUDIES

Authors: SHREFLER, JAMES - OKLAHOMA STATE UNIVERSITY; ROBERTS, WARREN - OKLAHOMA STATE UNIVERSITY; SUTHERLAND, AL - OKLAHOMA STATE UNIVERSITY; Webber Iii, Charles

Submitted to: Oklahoma Agriculture Experiment Station Departmental Publication
Publication Type: Monograph
Publication Acceptance Date: 2/14/2002
Publication Date: 6/1/2002
Citation: N/A

Interpretive Summary: Oklahoma watermelon producers are faced with the challenge of controlling many aggressive weeds with a limited herbicide arsenal. The pigweeds (Palmer, tumble, and spiny pigweeds) are among the most troublesome broadleaf weeds that limit watermelon yields. Although, there are several approved preemergence herbicides available for watermelon, these herbicides soften do not give adequate control of many of the weeds, and there are no registered postemergence herbicides for broadleaf weed control in watermelon for Oklahoma. Halosulfuron methyl is being developed as a possible new herbicide for use in watermelon for either preemergence or postemergence control of broadleaf weeds. Studies were conducted at three different locations (Bixby, Lane, and Hinton, OK) to assess the potential value of halosulfuron to Oklahoma watermelon production. The objective of these studies was to evaluate and compare the efficacy and crop safety of halosulfuron, approved herbicides, and combinations of halosulfuron and approved herbicides. All of the preemergence treatments gave essentially complete early control of Palmer amaranth and common lambsquarters at Bixby, spiny and tumble pigweed at Lane, OK, and Palmer amaranth, toothed spurge, and crownbeard at Hinton, OK. The preemergence application of halosufuron whether by itself or in combination did not reduce shoot length and dry weight at the 0.025 or 0.05 lb ai/a rate, except at the Hinton location where the higher rate of 0.05 lb ai/a resulted in some plant stunting. Halosulfuron applied postemergence provided only minimal weed control. This research indicates that halosufuron as a preemergence herbicide has a good potential to assist watermelon producers in controlling certain troublesome weeds.

Technical Abstract: Oklahoma watermelon producers currently have few options for controlling weeds. Broadleaf weeds are especially troublesome in that there are currently no approved postemergence broadleaf herbicides. There are several approved preemergence herbicides available for watermelon. However, these often do not give adequate control of many of the weeds that toccur in watermelon crops. Halosulfuron methyl is being developed as a possible new herbicide for use in watermelon. Studies were conducted at three different locations (Bixby, Lane, and Hinton, OK) to assess the potential value of halosulfuron to Oklahoma watermelon production. The objective of these studies was to evaluate and compare the efficacy and crop safety of halosulfuron, approved herbicides, and combinations of halosulfuron and approved herbicides. All of the preemergence treatments gave essentially complete early control of Palmer amaranth and common lambsquarters at Bixby, spiny and tumble pigweed at Lane, OK, and Palmer amaranth, toothed spurge, and crownbeard at Hinton, OK. The preemergence application of halosufuron whether by itself or in combination did not reduce shoot length and dry weight at the 0.025 or 0.05 lb ai/a rate, except at the Hinton location where the higher rate of 0.05 lb ai/a resulted in some plant stunting. Halosulfuron applied postemergence provided only minimal weed control. This research indicates that halosufuron as a preemergence herbicide has a good potential to assist watermelon producers in controlling certain troublesome weeds. Additional research needs to elaborate on the weed species controlled by halosufuron, and the interaction of soil type and herbicide rate on potential plant injury at higher application rates.