March 9, 2000
Three years of data from a long-term alfalfa trial is showing that cutting schedule does indeed influence variety performance. In fact, a plant scientist at North Dakota State University says yield potential should no longer be an alfalfa producer's primary selection criteria.
"I can't recommend a particular variety to a producer," says Dwain Meyer, a professor in the NDSU plant sciences department. "We used to say you should select a variety with a yield potential comparable to or better than the variety Vernal, but now I'd recommend making selections based on four characteristics."
The No. 1 selection characteristic, Meyer says, should be stand persistence, particularly for producers who are managing four-cut systems. The No. 2 characteristic is pest resistance (insects, diseases and nematodes). No. 3 is forage quality, as determined by improved relative feed value. Many of the new multifoliate varieties offer higher leaf-to-stem ratios, which is an important factor for dairy and cash-hay producers. No. 4 is forage yield potential. With all of these characteristics being roughly equal, a fifth criteria might be seed availability.
In Meyer's research, he is evaluating two four-cut systems, two three-cut systems and 12 alfalfa varieties. Vernal is the check. He established the plots in 1995 and initiated treatments in 1996. In one of Meyer's four-cut systems, harvest occurs at mid-bud, late-bud, 25-percent bloom and after a killing frost, but because all varieties are cut on the same day, harvest timing relies on an average maturity. In the other four-cut system, the cuttings (mid-bud, late-bud and 25-percent bloom) are set according to the maturity of each variety, with the fourth cutting occurring between 30- to 40-percent bloom. In other words, the second system does not use a single-day harvest for each cutting.
Likewise, both of the three-cut systems Meyer is studying are based on the individual maturities of the varieties. One system--with cuttings at late-bud, 10-percent bloom and 10-percent bloom--was the normal recommendation for producers. The second three-cut system schedules harvest at 10-percent bloom, 25- to 50-percent bloom and 25- to 50-percent bloom.
"For the first three production years, the best-yielding variety across all four management systems has been Magnum IV," Meyer says. "It has also been fairly consistent across all systems, as has the variety 5246."
While the variety WL 252 HQ has performed quite well under the four-cut systems, it has proven to be one of the lowest-yielding varieties under the three-cut systems.
And what about Vernal? Based on how NDSU researchers typically manage their plots under a four-cut system--which is to cut all varieties on the same date--10 of the other 11 varieties in the trial have out-yielded Vernal from 2 percent to 10 percent when disease wasn't a factor.
"Vernal is a late-maturing variety," Meyer says. "If we changed how we managed our research plots, Vernal might do better."
By contrast, DK 127 has been the second-highest yielding variety under the single-date four-cut system, but the variety's yield has been significantly less under the other four-cut and three-cut systems, Meyer says.
In 1999, Meyer's plots suffered the same fate as many of the region's alfalfa fields: winter injury. He says, "That persistence characteristic is really showing up, and it is something that tends to be found within certain varieties."
For example, Magnum IV, the highest-yielding variety during the first three years of the trial, yielded significantly less than 5246 in 1999 due to winter injury and some winter kill. Meyer says 5246 is a persistent variety.
"Pest resistence of an alfalfa variety can be a very important characteristic," Meyer says. "In 1999, potato leafhopper was the worst in more than 30 years. Normally, potato leafhopper is only occasionally an economic problem, and then only on the second harvest in the seeding year." Some newly released alfalfa varieties possess potato leafhopper tolerance, and third-generation leafhopper-tolerant varieties will soon be marketed.
Likewise, disease tolerance may be important in higher-moisture years. For example, Fusarium wilt was a major problem in 1997, and the forage yield of Vernal in Meyer's trials was 25 to 30 percent less than other varieties.
"That is why Vernal is no longer recommended," Meyer continues. "Many of the more than 40 new varieties released each year feature improved disease tolerance. Alfalfa producers should know what diseases are important in their areas and select varieties with tolerance."
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Source: Dwain Meyer (701) 231-8154
Editor:
Dean Hulse (701) 231-6136