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368 Ag Hall OSU Plant & Soil Sciences Department
Stillwater, OK 74078 |
NEWS |
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| Every year we maintain about 15 alfalfa variety test in Oklahoma. The main objective
of this testing program is to identify those varieties that are best suited for production
in Oklahoma. This helps producers make choices of which variety to use, and it helps seed
companies know which varieties to market in the state. A copy of a recent Production
Technology is enclosed which summarizes data through 1996. Of the 100 new varieties released each year, 15-20 new one are tested here. The following varieties have been well-tested and have shown a high yield potential. We established 10 tests-years as the minimum before we could recommend use of a particular variety. Some good varieties are entered into only one or two test and never reach this list.
Some producers continue to shop for seed by price, thinking that buying cheap seed will reduce their production costs and result in increased profits. This is frequently a false economy. Cheap seed may be good, but it is probably not as good as seed of the proven varieties. The true "Oklahoma Commons" generally yield about 10% less than the best varieties for Oklahoma. Some seed is sold at a greatly reduced price because its germination or purity is not good and the company wants to unload the seed. Check the tag on all seed purchased -- it should indicate results of a recent germination test and the amount of weed seed and foreign material in the bag. Check out the following table with the seed prices that are listed for various sources of seed and other hay prices to see which is the best buy in the long run.Seed Cost and Gross Income Per Acre Per Year Comparisons for Seed of Proven Varieties and an Unknown Variety with Different Planting Rates to Compensate for Seed Quality.
* A common seed lot. Seed Cost and Gross Income Per Acre Per Year Comparisons for Seed of Proven Varieties and an Unknown Variety with the Same Planting Rate.
* A common seed lot. Both tables were adapted from Alfalfa Stand Establishment Questions and Answers. OSU Extension Circular E 949. Obviously these comparisons between proven good varieties and common seed do not fit all situations. As disease and insect problems increase during a stand, the difference paid for seed of improved varieties will be paid off sooner. Also, as price per ton of hay increases, the seed cost difference is paid off sooner. (State Department of Agriculture data indicated $100/ton would be a more reasonable price.) Higher yields result in shorter recuperation times. Anything improving profits shortens recuperation time. If yield of both types is drastically reduced because of low soil fertility, it takes longer to recuperate additional seed costs. Lower average hay price would also lead to a slower time to recuperate cost differences.
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-- John Caddel |
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| New Stands - Producers planning to plant alfalfa this fall need to review
"Alfalfa Stand Establishment Questions and Answers", OSU Extension Circular
E-949 for an integrate approach to getting a good stand. Hopefully you have selected a
good site and seedbed preparation are such that you can make a timely planting in early
September. I do not generally recommend using a PPI (pre-plant incorporated) herbicide for
fall planting because: 1) Incorporating herbicides can ruin a good seedbed and delay the establishment of alfalfa. This is a major problem when moisture is limiting as it is in many areas this year. Most producers do a good job of preventing of weed seed production in previous crops, so weeds are not that big of a problem. 3) Cool-season weeds in fall-planted alfalfa very seldom prevent establishment of seedling alfalfa plants. I have only seen one case where alfalfa did not establish, and that was where alfalfa was planted no-till into wheat stubble. Good postemergence herbicide options are available if weed infestations merit treatment. So, get your alfalfa planted in early September on a good seedbed. Most of the alfalfa and weeds will emerge with the first good rain (one inch or more). Then, about 3 weeks after emergence, when you can see some green from the road, evaluate your weed problem. Read my comments in next month's NEWS for details on how to evaluate your weed problems and what to expect from postemergence weed control. Reminder - There are "Rotational Crop Restrictions" on many herbicides used on previous crops in Oklahoma. The reason for these restrictions is that there may still be enough herbicide residue in the soil to injure subsequent crops like alfalfa. Examples of planting restrictions for alfalfa are as follows:
**Field Bioassay means planting alfalfa and observing it to see that it emerges and grows normally. Some of the restrictions are probably longer that actually required, but until the product has been tested thoroughly and guidelines developed, it is industry's policy to make restrictions maximum to minimize their liability. The use of the sulfonylurea herbicides (such as GLEAN and AMBER) on the wheat crop before planting alfalfa has resulted in severely stunted alfalfa seedlings in a number of fields in western Oklahoma, primarily on high pH soils. The damage often is usually not noticed, since at low dosage levels, the alfalfa plants emerge and look fairly normal. Root of alfalfa plants are suppressed, however, and this results in stunted plants. This has been particularly evident after dry summers following herbicide application. To be safe, always read and follow crop restrictions on herbicide labels. This includes keeping accurate records as to: -- What chemical was applied. -- When it was applied. -- How much was applied.
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-- Jim Stritzke |
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