"Weeds can severely impact the quality of alfalfa and affect the overall value for hay growers. The most effective weed management program starts before alfalfa is planted and continues throughout the entire life of the stand."
Weeds compete for the same resources as alfalfa – space, sunlight, water and nutrients – reducing the quality of harvested alfalfa. In addition, heavy weed infestation in newly seeded alfalfa often suffocates alfalfa seedlings, resulting in thin stands.
"Early planting is one way to ensure a productive crop," Miller says. "The optimum time to plant alfalfa depends on the region, but typically it runs from mid-March to May. Generally, the earlier growers get the stand established, the less pressure they have from weeds that spring up during the abundance of warmer weather."
Once a healthy stand is well established, weed control is less of a concern and alfalfa becomes vigorous - at least until the stand begins to weaken due to age or other problems.
Effective crop management practices for weed control
There are several steps growers can take to ensure effective weed management and, ultimately, good stand establishment:
• Adjust soil fertility and pH – At least one year in advance of alfalfa planting, test the soil and make adjustments to correct soil pH and fertility. A soil pH range of 6.5 to 7.0 is ideal for new seedlings to establish and develop rapidly.
• Walk the fields – Before beginning a weed control program, accurately identify weeds. It is important to have an understanding of the different types of weeds and their life cycles.
• Prepare seedbed – Alfalfa requires a good seedbed to grow successfully. This includes a well-planned drainage system that prevents ponding as well as a firm ground. A good rule of thumb for an ideal seedbed is one that shows the depression of footprints or the bars of a tractor tire.
• Ensure right seeding depth – Good seed-to-soil contact is crucial in alfalfa establishment. Seeds placed too deep most likely will not emerge. Whereas, seeds placed at a shallow depth will dry out and die due to inadequate soil contact. An ideal depth of seed placement is one-fourth to one-half inch.
Alfalfa variety selection
Selecting the best alfalfa varieties also is one of the most important decisions growers can make in developing a productive crop. Many herbicides are available for specific uses on alfalfa during the life of a stand. Planting alfalfa varieties with the Genuity Roundup Ready (RR) gene can be a useful weed management tool and a way to handle some of the most difficult-to-control weed species.
The Genuity Roundup Ready trait enables growers to control grass and broadleaf weeds with a single glyphosate herbicide application in the seedling phase, resulting in a simplified and very effective weed management practice while maintaining crop and feed safety.
Spraying Roundup on the seedling crop is recommended at the three- to four-trifoliate leaf stage, and will promote a healthy stand establishment by controlling most seedling weeds.
"Using the Roundup Ready technology, coupled with a good weed control strategy, will help ensure a productive alfalfa crop for a number of years," Miller says.
"We understand farmers are looking at ways to improve their farming practices, and it's our goal to help them maximize their profits by providing resources that ensure the ongoing health of the soil for future harvests." FG
—From Pioneer news release
