By Blake Jackson
With forsythia blooming, it's crucial for forage managers to apply residual herbicides to prevent summer annual weeds, particularly grasses, from germinating.
Crabgrass, foxtails, panicum, and Japanese stiltgrass germinate at varying times, necessitating early intervention. Japanese stiltgrass emerges first, requiring timely pendimethalin application.
Pendimethalin (Prowl H2O, Satellite HydroCap) effectively controls certain annual grasses and broadleaf weeds in established perennial forage grasses. Apply 1.1 to 4.2 quarts per acre before weed germination or between cuttings.
Split applications (2-3 pt/A in early spring, 3-4 pt/A post-cutting) are more effective than a single high-rate application. These herbicides are safe for mixed cool-season grass/alfalfa stands but not other legumes. No pre-harvest/grazing interval is required for pendimethalin, but mixed alfalfa/grass stands need a 14-day wait.
Pendimethalin requires an inch of rainfall for activation; dew or light showers may not suffice, leading to poor control. It doesn't control established perennials like roughstalk bluegrass, which is best treated in fall or early spring. In alfalfa, Gramoxone/paraquat, Raptor, or Select/clethodim can offer some control after the first cutting.
Now is also the time to scout for winter annual and biennial weeds. Winter annuals (mustard species, chickweed, horseweed, etc.) and biennials (thistle, burdock, poison hemlock, etc.) should be treated before flowering and seeding. Smaller plants are more susceptible.
Perennial broadleaf weeds (dandelion, thistle, milkweed, etc.) and woody perennials (multiflora rose, autumn olive) are best treated in early summer at bud-to-bloom stage.
Effective herbicides include 2,4-D ± dicamba, triclopyr, clopyralid, and metsulfuron. NovaGraz is a new option for grass/white clover stands, preserving clover while controlling broadleaf weeds.
Timely herbicide application and scouting are essential for effective weed management in forage settings.
Photo Credit: gettyimages-r-j-seymour
Categories: Pennsylvania, Crops, Hay & Forage