Forage Trials Report: Fall weather rebound saved final harvest for some producers

Cows enjoy hay rolled out on the pasture at Spring Wood Dairy in Kinzers.

The 2016 Forage Trials Report summarizes performance data collected from ongoing forage trials at two sites in Pennsylvania. The report includes data from alfalfa and cool-season (forage) grass trials established at the Russell E. Larson Agricultural Research Center at Rock Springs and/or the Southeast Research and Extension Center at Landisville.

Weather in April for forage planting was excellent across much of Pennsylvania. Then spotty heavy rains caused some soil crusting, which resulted in poor stands in some areas. More normal weather patterns occurred in May, which allowed a lot of first crops to be harvested without getting wet. The weather patterns then became mixed over much of the state with adequate rainfall in some areas and devastating drought in others. Ultimately, many forage producers were heading into the fall with a forage shortage. Fortunately, weather conditions during September and October were ideal for forage growth, which provided a saving final harvest for some producers.

Alfalfa weevil populations were generally low with few reported outbreaks. Potato leafhopper infestations were average across most of the state, but the dry weather in some areas caused leafhopper damage to be more pronounced than in areas with adequate precipitation. Cereal leaf mite damage continues to be a problem for timothy production in some areas.

Although the trials contain up to 40 total entries, many of these are advanced experimental varieties or not currently offered for sale in Pennsylvania. After these entries are named and/or become available for purchase in Pennsylvania, they will be included in future reports.

Experimental alfalfa entries that become named varieties will be footnoted as such. Newly named varieties will be published in the Forage Trials Report only if they are entered as a commercial variety in the next available trial.

Varieties are ranked according to their yield performance. In addition, yield totals for the previous harvest years are reported, as well as average yields over the life of the stand. It is important to evaluate the average yields as well as the yields obtained this year because performance over a three- to four-year period is valuable in a long-term forage rotation.

The stand score, a visual estimation of the amount of groundcover, is given following harvest in the fall. The stand score is reported on a scale from 1 to 100, with 100 considered a perfect stand. This score is valuable as an indicator of varietal persistence.

Please keep in mind when reviewing the yield and stand tables that differences between varieties are significant only if the least significant difference (LSD) between varieties is exceeded. LSD is the minimum difference between any two varieties necessary for us to be 95 percent confident that this difference is not attributable to mere chance. For example, if variety A is 0.50 ton per acre higher in yield than variety B, then this difference is statistically significant if the LSD is 0.50 or less. If the LSD is 0.51 or greater, then we cannot be confident that variety A really yields higher than B under given environmental and management conditions.

The value for coefficient of variation is a measure of relative variation useful in evaluating the precision achieved in an experiment. In grain and forage trials, for example, the CV for yield often is between 5 and 20 percent. Acceptable levels of the CV vary for each trait measured. Confidence in the reliability of the experimental results declines as the CV increases. Uncontrollable or immeasurable variations in soil fertility, soil drainage and other environmental factors contribute to increased CV levels.

Many varieties of alfalfa exist, and selection of the appropriate variety is an important management decision. This report lists performance data for those varieties included in the Penn State Alfalfa Variety Testing Program. Evaluation trials include both commercially available and advanced experimental varieties. Trials are initiated each year at the Rock Springs and Landisville research stations. In each trial, collection of yield, stand and other data continues for a maximum of four years or until the stand becomes so depleted that data collection is no longer worthwhile.

Trials at both locations are established on well-drained Hagerstown silt loam soils. Major site differences are likely to be reflected in the longer growing season, slightly elevated temperatures, and tendency toward late summer drought at the Landisville site.

Keep the following points in mind when evaluating alfalfa variety performance data:

• Selection of a variety on the basis of yield performance alone is generally less satisfactory than selections that also consider stand score and pest resistance.

• Conditions on most farms are such that several varieties may perform nearly equally. It usually is not necessary to rely on a single variety.

• No variety, regardless of its excellence, can thrive under poor management. Good management considers all aspects of alfalfa production, including seedbed preparation, lime and fertilizer, seeding, pest control, harvest, storage and postharvest treatment. Many modern varieties are adapted to intensive management.

Fall dormancy ratings of alfalfa range from 1 (very dormant) to 9 (having no dormancy). Varieties that have less fall dormancy (higher numerical rating) regrow faster after harvest and exhibit greater growth in the fall compared to those varieties with more fall dormancy (lower numerical rating).

Disease and insect resistance may be the most important attributes of an alfalfa variety. The ratings for pest resistance given in this report can serve as a good indicator of a variety’s potential performance in your area. Be aware of your pest resistance needs and choose the appropriate varieties.

Sclerotinia stem and crown rot is becoming a serious concern for growers throughout the state because there is little plant resistance to the disease. Late summer no-till seedings seem to be more susceptible to the disease. Newly established seedlings are very susceptible to infection in the fall when the fungus is active. Plants are attacked rapidly by the pathogen and die the following spring. Plants established in the spring are more resistant to the pathogen and are not as severely damaged as the younger plants. The fungus survives as hard, black structures (sclerotia) on or near the soil surface. In the fall, the sclerotia produce spores that cause infection. Plowing buries sclerotia, thus reducing inoculum and subsequent infection.

Resistance to Aphanomyces can be found in some of the newest varieties. Aphanomyces eutiches is a soilborne fungus with behavior and requirements similar to Phytophthora. It is a wet-soil seedling pathogen and can be expected to thrive under cool, waterlogged conditions. Resistance may be beneficial when growing alfalfa on poorly drained soils. More specific information about many alfalfa diseases is included in the current Penn State Agronomy Guide.

Crown and root rot complex is still a problem. Because of the complexity of the pathogens involved, resistance to this disease is not very high in any variety. Good management slows the progress of this disease. More specific information is included in the current Penn State Agronomy Guide.

Plant breeders develop alfalfa varieties by selecting from genetically diverse populations. Within such populations, individual plants may vary widely in their response to a particular disease or insect. Some may be highly resistant and others very susceptible. A particular pest resistance rating usually reflects the response of the majority of plants in the variety. In our trials, varieties with the most pest resistance ratings of “moderate” or higher usually have shown better long-term performance.

To select alfalfa varieties based on the trial results, follow these suggestions:

1. Determine which of the trial sites most resembles your farm in terms of soil and growing season. Performance data of varieties at this site are likely to provide more relevant selection information.

2. Look at the performances of the varieties at both trial sites. Varieties that do equally well at both sites are probably adapted to a wider range of environmental conditions.

3. Performance data over several years can be very useful in selecting a variety since some varieties seem to decline with age more rapidly than others.

4. For long-term rotations, the most recent harvest-year data should receive major consideration. If you plan to harvest the alfalfa for three years or less, then high performance during the early years should be given major consideration.

5. Disease- and pest-resistance ratings should be examined in relation to yield, especially if your area is known to have problems with alfalfa diseases and pests. For example, Phytophthora root rot resistance may be exceptionally important on farms with moderately to poorly drained soils.

Tables 2 through 9 offer guidelines for assessing the production potential of various alfalfa varieties.

Tables 11 through 13 and 15 through 18 offer guidelines for assessing the production potential of various grass varieties. Tables can be viewed at: http://bit.ly/ForageReports.

Many farmers in Pennsylvania could benefit from including some cool-season grasses as an integral part of their forage program. The tables summarize the yield potential of many perennial grass varieties in our research trials at Penn State’s Russell E. Larson Research Center at Rock Springs.

Our soil fertility program is designed around maintenance applications of phosphorus and potash to meet the soil test requirements. Seventy pounds of available nitrogen are applied in early April with an additional 50 pounds applied after each harvest except the last one.

The first cutting in the perennial cool-season forage grass trials is made when an individual variety reaches mid to late boot. Subsequent harvests are then made at intervals of 35 to 40 days, with the exception of the final harvest, when all plots are harvested on the same day. All plots are harvested four times throughout the growing season, weather permitting, except in the establishment year.

Although production for each cutting in a given year varies among species, most varieties produce one-third to one half of the total annual production in the first cut. Yields are not greatly reduced if a three-cut system is used. Quality will be increased by early and frequent cutting. Choose a species that fits the farm’s capabilities and the operator’s management scheme. See the current Penn State Agronomy Guide for specific recommendations about establishment, fertilization and other management considerations.

In fall 2015, a Short-lived Cool-Season Grass Trial was seeded at Rock Springs. The trial was planted on Sept. 18. There were two different management treatments: a single-cut system and a multi-cut system. The cereal grasses were cut using the single-cut system and the annual ryegrasses were cut using the multi-cut system. Some of the ryegrass varieties were entered in both cutting systems. With the multi-cut system, grasses were cut about every three weeks and the plots were cut three different times based on maturity. The first cut was taken at flag leaf (target 20 inches). The varieties in the single-cut system were cut when they reached the early to mid-boot stage. Cutting started on May 2 and was completed June 13. Our soil fertility program is designed around maintenance applications of phosphorous and potash to meet soil test requirements. Plots received 30 units in the fall, 100 units of nitrogen in the spring at green-up, and 50 units after each cutting for the multi-cut system. See the current Penn State Agronomy Guide for specific recommendations about establishment, fertilization, and other management considerations.

Editor’s note: The forage trial results charts are available online at: http://bit.ly/ForageReports.

The trials report was prepared by William Boone, forage variety trials manager; W. Scott Harkcom, farm manager; and Marvin H. Hall, professor of forage management.

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