Alfalfa (Medicago sativa), a globally important perennial forage legume, is widely cultivated in China, where effective weed management is essential for sustainable production. Chemical weed control, primarily relying on the herbicide imazethapyr, represents the most common strategy. Reliance on a single-herbicide program, however, may lead to inconsistent weed control under field conditions and may raise environmental concerns when higher application rates are used. To address this challenge, a two-year field study (2022–2023) was conducted to reduce herbicide inputs and identify new weed management options through tank mixtures. Initial screening identified imazethapyr, prometryn, imazapic, and 2,4-DB as safe and effective against broadleaf weeds. To broaden the control spectrum and reduce total herbicide use, haloxyfop-R-methyl was tank-mixed with each of the four broadleaf-active herbicides. The combinations haloxyfop-R-methyl + imazethapyr (36.5 + 56.3 g a.i. ha−1) provided broad-spectrum weed control without compromising alfalfa performance and, importantly, reduced herbicide input at least by 25% of the recommended label dose. Additionally, the mixture of haloxyfop-R-methyl with 2,4-DB (36.5 + 506.3 g a.i. ha−1) achieved effective, broad-spectrum weed control, increased alfalfa yield, and reduced total herbicide input at least by 25% of the recommended label dose. This mixture offers a useful option for diversifying weed management programs and reducing reliance on repeated imazethapyr applications. These tank mixtures represent sustainable and practical components of an integrated weed management system in alfalfa production.
Wang et al. (Thu,) studied this question.