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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #366938
Title: New herbicides and tank mixes for control of waterhyacinth in the Sacramento-San Joaquin Delta

Author
item KYSER, GUY - University Of California, Davis
item Madsen, John
item MISKELLA, JOHN - University Of California, Davis
item O BRIEN, JON - California Department Of Boating And Waterways

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2020
Publication Date: 8/31/2021
Citation: Kyser, G.B., Madsen, J.D., Miskella, J., O'Brien, J. 2021. New herbicides and tank mixes for control of waterhyacinth in the Sacramento-San Joaquin Delta. Journal of Aquatic Plant Management. 59s:78-81. https://apms.org/journal/.

Interpretive Summary: We tested the effectiveness of carfentrazone, flumioxazin, imazamox, florpyrauxifen-benzyl, and glyphosate for control of waterhyacinth. We also tested combinations of flumioxazin or carfentrazone with glyphosate or imazamox. The three most effective herbicides (at more than 95% control) were florpyrauxifen-benzyl, glyphosate, or the tank mix of flumioxazin and imazamox.

Technical Abstract: The Sacramento-San Joaquin Delta is the largest freshwater estuary on the west coast of the United States. Delta habitat and economic utility are compromised by waterhyacinth, a floating aquatic weed. Standard control measures for waterhyacinth include foliar treatment with glyphosate or 2,4-D. We have conducted trials over three seasons to evaluate efficacy of newly registered, low-rate aquatic herbicides. In 2017, we evaluated waterhyacinth control using carfentrazone (133 g ai ha-1), flumioxazin (322 g ai ha-1), imazamox (280 g ae ha-1), and florpyrauxifen-benzyl (350 and 701 g ai ha-1), as well as various tank mixes, compared with a standard rate of glyphosate (1681 g ae ha-1). Plots were established in floating 1-m2 quadrats, and treatments were replicated four times. All treatments were applied in 935 L ha-1 solution with 3.5 L ha-1 Agridex surfactant. We also included treatments with glyphosate (1681 g ae ha-1) in lower spray volumes of 234 and 468 L ha-1. We took biomass samples 8 WAT. Three treatments reduced waterhyacinth biomass by >95%: florpyrauxifen-benzyl (701 g ai ha-1), flumioxazin + imazamox (322 + 280 g ai/ae ha-1), and the 468 L ha-1 application of glyphosate (1681 g ae ha-1). Flumioxazin + imazamox gave better than additive control, while other tank mixes (carfentrazone + imazamox, carfentrazone + glyphosate, flumioxazin + glyphosate) gave less than additive control. Florpyrauxifen-benzyl and flumioxazin + imazamox may be effective alternatives to glyphosate for controlling waterhyacinth with reduced rates of active ingredient. Glyphosate applied in a spray volume of 468 L ha-1 produced better control than the same rate of glyphosate in 935 L ha-1, suggesting that spray volume optimization may be a useful topic for future research.