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NEWS |
CONTENTS OF NEWSLETTER
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We are frequently asked if there is a way to thicken-up old stands. For years, researchers have reported that the practice of "thickening-up" old stands is not effective. In Oklahoma we have found that very few plants become established within 1 foot of an old plant. Even in spring following poor stand establishment of fall-sown alfalfa (7 months old), new seedlings seldom get tall enough to be cut by the sickle bar. Dozens of seed per square foot may germinate, but few become a productive part of the stand under good conditions. There are news articles from time to time suggesting that thickening up old stands can be successful. What new information has brought about the change? There is no new research to suggest that interseeding alfalfa into old, thin alfalfa stands will be successful. Where this practice has worked, several key factors were present which are not common in most alfalfa meadows: light, well-drained soils with low disease levels; the availability of irrigation to quickly bring up new seedlings; and a weed complex which allows burn-back type herbicides to work effectively. The odds are firmly against successfully thickening-up old alfalfa stands. What Kills Seedlings in Established Alfalfa Stands? Environments surrounding germinating alfalfa seeds in an established alfalfa stand is as hostile as possible. Diseases, insects, and nematodes have had years to build up in the soil and in the root and crown tissue of older plants. As soon as young, fresh tissue is available (the germinating alfalfa seedling), these pests attack, and this is why many researchers have reported that seedlings emerge but seem to "melt away" in old alfalfa stands. The area around old plants is also dry and infertile. Old alfalfa plants are efficient in removing essentially all the water and nutrients in the area. One response to the seedling disease problem has been a recommendation to increase the amount of fungicide (e.g. Apron) placed on the seed. It has been suggested that farmers take Apron-treated commercial seed and retreat the seed with a second application of the fungicide before sowing. This load of Apron could injure the seedling and is probably illegal. The label recommendations for Apron fungicide are closely adhered to by seed companies; an additional treatment provides greater than the recommended rate of fungicide on the seed. Even if it works we don't recommend using products off label. Other reasons why young alfalfa seedlings seem to "melt away" after interseeding, include autotoxicity and competition from older alfalfa plants. Competition is for light, water, and nutrients. Even very thin old stands provide stiff competition for light and water as new seedlings attempt to establish. In addition, the old plants emit compounds toxic to the germination and growth of new alfalfa seedlings. What Should a Grower Do? For producers with thin alfalfa stands, the best advice is to destroy the stand and rotate to a different crop for at least one year (preferably several years). This allows the pest pressures and autotoxic compounds in the soil to dissipate completely before new alfalfa seedlings are established. Another benefit is the control of troublesome weeds. Conclusions -- Stop and think before you consider "non-stop" alfalfa. Unless your farm is unique (light soils, irrigation, disease-free, low weed pressures, etc.), attempting to successfully thicken-up old alfalfa stands will usually fail. A recipe for unique situations What if a grower does not have a full year available before new alfalfa acres must be planted? If an old stand is moldboard plowed, a new stand can be established in approximately 6-8 weeks. However, waiting less than one full year before establishing a new stand is risky. If you know you will need to start a new stand next year
(2000) but want to keep an old field in alfalfa production, you might want to consider the
following. Do not overlook or forget the conditions. Conditions: Deep, sandy or sandy loam soil Excellent drainage (internal and surface) Irrigation is available in abundant supply Begin after first or second cutting (no later than July 5) 1. Plow alfalfa with a moldboard plow, turning under all the above ground plant parts (leaves and stems) as deep as possible (preferably 10 to 12 inches). 2. Irrigate with at least 3 inches of water. Steps 1 and 2 should get rid of the autotoxity problems and start replenishing soil moisture. 3. Disk and smooth the field. 4. Apply fertilizer and lime as prescribed by a soil test. Three or four times the annual phosphorus rate would be a good idea. 5. Apply at least 10 inches of irrigation. The 13 inches of water by now should have the soil profile moist to a depth of about 6 feet. 6. Smooth the field and firm the seed bed for planting in early September. 7. Irrigate with .75 to 1 inch of water (1 to 3 times) until plants have emerged and are growing. 8. Scout the field frequently for insects and weeds and apply pesticides as needed to keep the stand healthy and growing. 9. Do not cut or graze before mid April of the following spring. Skipping or short-cutting any of the above steps will nullify the others and risk losing the money invested in getting the new stand established. -- John Caddel |
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Foundation seed production is conducted under contract with Oklahoma Foundation Seed Stocks (OFSS). A contract is negotiated between OFSS and a producer, group of producers, seed vendor, or combinations of these. There are certain rules and policies for Foundation seed production such as isolation distances between a seed field and other alfalfa fields, certain field history (number of years since alfalfa), etc. These conditions are subject to inspection by OFSS. Specialized alfalfa seed production may serve as a good alternate crop for many producers who are looking for a good cash crop with fewer risks than soybeans, peanuts, sunflowers, corn, etc. A generalized alfalfa seed production system is described below that begins with 30 pounds of breeders seed and results in more than 8000 lbs of Foundation seed in 3 years. Suggested planting rates and seed yields are well within norms for Oklahoma. Price for Foundation seed is negotiable and should more than cover the costs of production. After the first year of Foundation seed production, certified seed production may begin and result in nearly 0.8 million pounds of certified seed in 5 years. Anyone interested in producing Foundation alfalfa seed should contact OFSS (405-624-7041) about the regulations and John Caddel about additional production details. Seed Production Scheme for OK 169 Alfalfa 1999 - - Plant 30 lbs of breeders seed on 15 acres in 40-inch rows for Foundation seed production. |
Year 2000 Harvest 2500 lbs of Foundation seed (150 lbs/ac on 15 ac). Sell to OFSS or as VNS. |
Year 2001 Harvest 3000 lbs of Foundation seed (200 lbs/ac on 15 ac). Sell to OFSS or as VNS. |
Year 2002 Harvest 3000 lbs of Foundation seed (200 lbs/ac on 15 ac). Sell to OFSS or as VNS. |
Certified Seed Production
Year 2000 Plant Foundation seed on 450 ac at 5 lbs/ac. |
Year 2001 Plant Foundation seed on 600 ac at 5 lbs/ac. |
Year 2002 Plant Foundation seed on 600 ac at 5 lbs/ac. |
Certified Seed Harvest Year |
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Acres/year planted |
2001 |
2002 | 2003 | 2004 |
| 450 ac from 2000 planting | 67,500 lbs (150 lbs/ac) |
90,000 lbs (200 lbs/ac) |
90,000 lbs (200 lbs/ac) |
- - |
| 600 ac from 2001 planting | - - | 90,000 lbs (150 lbs/ac) |
120,000 lbs (200 lbs/ac) |
120,000 lbs (200 lbs/ac) |
| 600 ac from 2002 planting | - - | - - | 90,000 lbs (150 lbs/ac) |
120,000 lbs (200 lbs/ac) |
| Total Certified Seed Produced | 67,500 lbs | 180,000 lbs | 300,000 lbs | 240,000 lbs |
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As alfalfa stand populations diminish, cool-season weeds such as downy brome and shepherdspurse compete with the alfalfa and produce significant forage. As a result, quality of hay decreases and producers are forced to use herbicides to extend the stand-life, or plow up thin stands. As stands thin, the return on investment quickly decreases due to weed control cost and reduced alfalfa production because of low stem densities (less than 20/sq. ft.). If producers are in the cattle business, then over-seeding with a cool-season forage might be a profitable option. A mixture of alfalfa-grass should provide high quality hay for beef cattle, and grazing grass mixed with alfalfa should reduce the bloat problems associated with grazing alfalfa. In mid-October 1998, three over-seeding experiments were initiated in south central Oklahoma. Treatments included three forage enhancement treatments (no overseeding, wheat drilled at 120 lb/A, ryegrass drilled at 25 lb/A) and two pest control treatments (no pesticides, weed and insects controlled). Moisture at the time of over-seeding was good to excellent at all three locations and weeds had emerged, but were still small seedlings. By January, substantial fall growth of wheat and ryegrass occurred at all three sites. Forage yields from the wheat and ryegrass over-seeded treatments varied from 0.75 and 1.0 tons per acre (tons/A). The major component of the forage was the over-seeded grass and some alfalfa with less than 1% of this yield composed of weeds. Treatments without wheat or ryegrass yielded from 0.1 and 0.27 tons/A of forage with approximately 16-25% weeds. From January to March, an additional 0.5 to 0.75 tons/A was produced in the wheat and ryegrass over-seeded treatments. Wheat and ryegrass out-competed the weeds, and as a result, weedy grasses and broadleaf weeds made up only 5% of the total forage. In the treatments without wheat and ryegrass, yields only increased from the first forage harvest by 0.25 to 0.35 tons/A, with weeds comprising from 30 to 70% of the total forage production. In May, ryegrass and wheat treatments produced an additional 1 to 1.25 tons/A, with less than 5% weeds. Forage quality analysis taken from the March forage harvest indicated adequate quality from the wheat and ryegrass over-seeded treatments. Wheat and ryegrass combined with alfalfa resulted in crude protein values more than 15 %. In plots with no over-seeding and pest control, the protein averaged 25%. The decrease in protein for the over-seeded plots is due to the abundance of wheat or ryegrass. Both these grasses would supply excellent forage quality for beef production. Total forage production from grazed and over-seed plots by time of first harvest in May was 2.25 to 3 tons/A of forage. In comparison, yield from the hay treatment without pesticides and no over-seeding averaged 0.5 to 2 tons/A with 75% weeds. When pesticides were used in hayed plots to control insects and weeds, the yields were 1.25 to 2.25 tons/A with 5 to 30% weeds. Based on these studies, we feel that there is some real potential for drilling wheat or ryegrass into thinning alfalfa stands and then grazing these areas in late winter and early spring. Both of the grasses were able to produce good forage yields and out-compete the weeds with only 100 lb/A of 18-46-0 additional fertilizer applied down the boot at time of drilling. -- Chad Cummings
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Below is an example of a weed description page. Users on the web may click on the small images at the bottom to see enlargements. If you have not checked out the web site in a while, try it to see what is there alfalfa.okstate.edu Let us know if you have problems or find things that we did incorrectly. Thanks. |
--Jim Stritzke, Alfalfa Weed Control
Specialist |
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October 21, 1999 Oklahoma Alfalfa Expo. Chickasha. Details will follow in the NEWS. Sponsored by Oklahoma Alfalfa Hay & Seed Assoc., Grady Co. Cattle Producers Assoc., Grady Co. Alfalfa Assoc., and Oklahoma Cooperative Extension Service. Anyone wanting to list alfalfa meetings may contact John
Caddel with the particulars. His mailing address and phone are listed below. Fax
405-744-0354. Email- caddel@okstate.edu |
