Varietal Tolerance of Cucurbitaceous Crops with S-metolachlor Applied Postemergence
Date
2024-06-01
Journal Title
Journal ISSN
Volume Title
Publisher
HortTechnology
Abstract
Cucurbit crops comprise ∼25% of the vegetable acreage in the mid-Atlantic and Northeastern United States. However, options for postemergence weed control in these crops are limited. Overlapping herbicides is a technique that involves sequential applications of soil-applied residual herbicides to lengthen herbicidal activity before the first herbicide dissipates. Residual herbicides such as S-metolachlor will not control emerged weeds, but weed control efficacy may be extended if these herbicides are applied after crop emergence, but before weed emergence occurs. Currently S-metolachlor is not labeled for broadcast applications over cucurbit crops. Greenhouse studies were conducted to evaluate pumpkin, cucumber, and summer squash variety response to varying S-metolachlor rates. S-metolachlor was applied at 1.42 and 2.85 lb/acre at the two-leaf stage of pumpkin and 0.71, 1.42, 2.85, and 5.7 lb/acre at the two-leaf stage of cucumber and summer squash. Cucumber showed a greater response to S-metolachlor with up to 67% injury observed at 5.70 lb/acre. S-metolachlor applications to pumpkin and summer squash resulted in less than 6% injury, regardless of application rate or crop variety. S-metolachlor applied at 2.85 lb/acre reduced pumpkin and cucumber dry weight 6% and 19%, respectively, but did not reduce squash dry weight. S-metolachlor reduced cucumber dry weight 78% for all varieties. Pumpkin varieties ‘Munchkin’ and ‘Baby Bear’ exhibited a 23% difference in dry weight, but no other differences were observed among other varieties because of S-metolachlor applications. Summer squash varieties ‘Respect’ and ‘Golden Glory’ exhibited a 31% difference in dry weight, but no other differences were observed among other varieties. Results show that pumpkin and summer squash demonstrated good crop safety when S-metolachlor was applied as a broadcast treatment after crop emergence. However, caution should be urged when applying this herbicide to cucumber.
Description
This article was originally published in HortTechnology. The version of record is available at: https://doi.org/10.21273/HORTTECH05420-24. © American Society for Horticultural Science 2024
Keywords
Cucumis maximus, Cucumis sativus, Cucurbita pepo, Cucurbita pepo subsp. pepo, herbicide, injury
Citation
Vollmer, Kurt M., Lynn M. Sosnoskie, Mark J. VanGessel, and Thierry E. Besançon. "Varietal Tolerance of Cucurbitaceous Crops with S-metolachlor Applied Postemergence", HortTechnology 34, 3 (2024): 388-395, https://doi.org/10.21273/HORTTECH05420-24