Spring is a critical time to control weeds in alfalfa. For Roundup-ready or tolerant varieties, glyphosate applications sprayed in early spring can assist alfalfa in effectively overcoming emerging weeds, but Roundup isn’t the only good weed control option.
When weeds grow faster than stressed alfalfa, seedlings are robbed of moisture, nutrients and light. Left uncontrolled, weeds can thin stands, weaken plants and lower yields. For broadleaf weeds, mowing may be an option while the alfalfa is growing slowly. Adjust mowing height so several leaves remain on the seedlings after clipping to aid in alfalfa regrowth. However, if mower clippings smother young alfalfa seedlings, then alternative herbicide application may still be your best weed control option.
The Nebraska Extension “Guide for Weeds, Disease and Insect” publication EC-130 provides comparison herbicide response ratings. When establishing new alfalfa stands, Eptam, Balan DF and Trust are labeled. For seedling alfalfa, post-emergent herbicides include: AIM, Moxy 2E, Poast, Buctril, Raptor, Select Max, Prowl H2O, Warrant, Pursuit, Arrow and Butyrac 200.
For established alfalfa, labeled broadleaf or grassy herbicides include: Aim, Moxy 2E, Butytrac, Chateau, Gramoxone, Karmex, Metribuzin, Prowl H2O, Treflan, Arrow, MCPA Amine, Warrant, and Velpar.
Remember that bottom-line improved herbicide effectiveness begins with applying products early while the weeds are less than 4 inches tall. As always, read and follow label directions for application rates and conditions. — Todd Whitney, Nebraska Extension educator
