2005 Ohio Forage Performance Trials

Alfalfa

     Alfalfa has the highest combined yield and quality potential of any adapted perennial forage grown in Ohio. It is the state's largest single hay crop, being grown on about one-half of the total hay acres. Alfalfa requires well-drained soils with near-neutral pH (6.5-7.0) for greatest production and persistence. Alfalfa trials are initiated each year and data is collected for at least four years unless the stand becomes so depleted that further testing is no longer worthwhile; variety performance should be evaluated over several sites and years.

Guidelines for Selecting Alfalfa Varieties
     To capitalize on alfalfa's potential, select high-yielding varieties with resistance to problem diseases. Consider these factors when selecting alfalfa varieties for Ohio:

1. Yield. Yield is the major factor in determining profitability of an alfalfa stand. Select varieties with high yields over several locations and years. Table 3 shows this comparison in percent of the average yield. Varieties that perform equally well across several locations and years are probably adapted to a wider range of environmental conditions. Stable yield performance across several environments is important because soils may vary on your farm and weather conditions vary from year to year. Conditions on most farms are such that several varieties may perform equally well.

2. Persistence. Another important consideration beyond yield is how long the stand will last. Study variety performance by age of stand to get an estimate of longevity of stand productivity. Some varieties may decline with age more rapidly than others. This may influence your choice of variety depending on how long you intend to keep the stand in production. For long-term rotations, choose varieties with good disease resistance and good performance in the fourth year of production. If you plan to harvest alfalfa for three years or less, then high performance during early years of the stand should be given major consideration.

3. Fall dormancy (FD). Alfalfa varieties with fall dormancy ratings of 1 through 5 are considered adequately winter hardy for Ohio conditions while those of 6 or higher are not considered adapted. Varieties with higher fall dormancy ratings tend to grow at a lower temperature. Thus they begin to grow earlier in the spring and later into the fall, extending the growing season. The fall dormancy rating does not correlate well with winter hardiness within the range of varieties adapted to the Midwestern USA.

4. Disease resistance. Variety selection based on yield performance alone is less satisfactory than selections that also consider disease resistance characteristics. Resistance to specific disease-causing pathogens may be the most important attribute in an alfalfa variety. Pathogens can dramatically reduce yield and persistence of susceptible varieties. In a recent evaluation of older versus newer alfalfa varieties we found that varieties released in the mid-1990’s yielded more (0.25 ton per acre more each year) and persisted longer than older varieties, primarily because of improved resistance to diseases that affected the trial. For more information on alfalfa diseases and varietal resistance to specific diseases, go to the following websites:
http://www.uwex.edu/ces/forage/pubs/varinfo.htm

5. Insect resistance. Alfalfa varieties have been developed for resistance to potato leafhopper (PLH), which is the most consistently damaging insect pest of alfalfa in Ohio. This report includes several trials where yield tolerance to PLH damage is being evaluated. Please note that the PLH resistant varieties are not resistant to the alfalfa weevil, and they will need to be protected from that pest like all standard alfalfa varieties when weevil populations exceed the economic action threshold.

6. Compare to check variety. For comparisons of varieties across several trials, always compare varieties to the same check planted within the trial. The variety Vernal is used as a check in all Ohio trials.

7. Use good management. No variety can produce well under poor management. Good management considers all aspects of alfalfa production: seed bed preparation, liming and fertilization, seeding, pest control, harvest, storage, and post harvest treatment. Many newer varieties are better adapted to intensive management.

Summary of 2005 Alfalfa Crop Conditions

    The growing season began with a warmer than normal average daily temperatures in April, then cooler temperatures in May, followed again by above normal temperatures for most of the remainder of the season. Overall, rainfall was below normal. The rainfall pattern for the year was atypical with periods of drought and spotty showers.
    Most alfalfa varieties began the growing season with good stands. Forage yields in 2005 were slightly higher than those in 2004. The 2003 seeding at Wooster had the highest yields with near normal rainfall (except June), and above average temperatures. Alfalfa weevil populations were low with only a few pockets in the state requiring insecticide application. Insecticide applications were used to control PLH infestations in the standard sprayed trials only. Leafhopper activity was low to moderate at North Baltimore and Wooster, but very high for the second and third harvests at South Charleston.
    No insecticide was applied to control potato leafhopper in the potato leafhopper resistance trials. Those trials are a continuing effort to evaluate the new leafhopper resistant alfalfa varieties. Vernal, 54V54, and DK140 were used as PLH-susceptible check varieties. This year we established a new regional effort in cooperation with Iowa State University to test alfalfa varieties for yield tolerance to PLH feeding. Yield tolerance to PLH will be developed from data collected over two years and two locations (S. Charleston, OH and Ames, IA). Yield data will be used for those cuttings when PLH populations exceed the standard economic threshold. The PLH yield index for each variety will be the percentage of its yield improvement over the yield of three PLH susceptible varieties (5454, DK140, and Vernal). The PLH yield index tolerance ratings for the varieties planted in 2005 will be updated next year by using the 2006 yield data collected during cuttings when PLH populations exceed the economic threshold. The leafhopper resistant varieties are not resistant to alfalfa weevil, and will need to be rescued if weevil populations exceed economic thresholds.
 

Table 1. Weather data summary for the 2005 growing season

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