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Title: Post-directed weed control in bell peppers

Author
item WEBBER III, CHARLES
item SHREFLER, JAMES - OKLAHOMA AGRICULTURE EXPERIMENT STATION
item BRANDENBERGER, LYNN - OKLAHOMA STATE UNIVERSITY

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2011
Publication Date: 5/6/2012
Citation: Webber III, C.L., Shrefler, J.W., Brandenberger, L.P. 2012. Post-directed weed control in bell peppers. Proceedings of Horticultural Industry Show, January 5-6, 2012, Tulsa, Oklahoma. p. 152-155.

Interpretive Summary: Organic pepper (Capsicum annuum L.) producers need appropriate herbicides that can effectively provide post-emergent weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of a potential organic herbicide on weed control efficacy, crop injury, and yields. The experiment included Scythe (registered trademark) (57% pelargonic acid) applied post-directed at 3, 6, and 9% v/v application rates, plus an untreated weedy-check and an untreated weed-free check with 4 replications. Bell pepper, 'Jupiter,' was transplanted on May 28, 2010 into 1 row on 91-cm wide raised beds. The primary weeds included smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.], cutleaf groundcherry (Physalis angulata L.), and spiny amaranth (Amaranthus spinosus L.). Scythe was post-directed applied on June 16 and reapplied 8 days later (June 25). Smooth crabgrass (55.6%) and cutleaf groundcherry (66.3%) control peaked at 1 day after initial treatment (DAIT) with the 9% application rate. Scythe at 9% v/v rate produced the greatest crop injury at 1 DAIT (13.75%). The sequential application of Scythe did not significantly increase grass or broadleaf control. Although weed control and crop yields increased as application rates increased, the less than satisfactory weed control produced significantly lower pepper yields than the weed-free treatment. These results provide producers with information for optimizing weed control with pelargonic acid.

Technical Abstract: Organic pepper (Capsicum annuum L.) producers need appropriate herbicides that can effectively provide post-emergent weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of a potential organic herbicide on weed control efficacy, crop injury, and yields. The experiment included Scythe (registered trademark) (57% pelargonic acid) applied post-directed at 3, 6, and 9% v/v application rates, plus an untreated weedy-check and an untreated weed-free check with 4 replications. Bell pepper, 'Jupiter,' was transplanted on May 28, 2010 into 1 row on 91-cm wide raised beds. The primary weeds included smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.], cutleaf groundcherry (Physalis angulata L.), and spiny amaranth (Amaranthus spinosus L.). Scythe was post-directed applied on June 16 and reapplied 8 days later (June 25). Smooth crabgrass (55.6%) and cutleaf groundcherry (66.3%) control peaked at 1 day after initial treatment (DAIT) with the 9% application rate. Scythe at 9% v/v rate produced the greatest crop injury at 1 DAIT (13.75%). The sequential application of Scythe did not significantly increase grass or broadleaf control. Although weed control and crop yields increased as application rates increased, the less than satisfactory weed control produced significantly lower pepper yields than the weed-free treatment.