|
|
|
Welcome!
Welcome to the first issue of the Virginia Soybean Update, a monthly and sometimes bi-monthly newsletter that I've been wanting to begin. Now with over a year under my belt as your Soybean Specialist and feeling more comfortable with Virginia's cropping systems and soybean production in general, I've decided to take the plunge and try to get important and timely topics regarding soybeans to you. Although I am the only contributing author in this first issue, I hope to entice other Specialists and Agents to contribute in the future. I hope you will find the information valuable. Please let me know if the information is useful; feedback is always appreciated.
The 1998 Soybean Production Guide
Many of you have been requesting a new and revised soybean production guide. Over the last 6 months, the guide has been undergoing revision and should finally be ready within a month. I will distribute 1 or 2 copies to each county office. Additional copies can be obtained by request, but due to limited funds for printing, the guide will not be distributed in large numbers as in the past. Hopefully, a web-version of the guide will be available in the near future. The web version should allow easier and more timely updates. In light of the rapid changes in soybean varieties and crop protection chemicals, this should be most beneficial.
Let me apologize for not getting the guide to you earlier, when you needed it. I take full responsibility of this. Most reviews from authors were back to me by January, but due to poor time management on my part, I was unable to review the guide in a timely manner. Another holdup was in the variety selection chapter. This was in need of major revision, especially with all the new herbicide-tolerant varieties. Updating this took longer than expected. I also chose to hold off and put as many of the newer herbicide-tolerant varieties in this chapter as possible due to the high demand, even if Virginia Tech had not tested them. Some of the information in this chapter is incomplete due to our lack of experience with those varieties, but most of the information is complete.
For County Agents, I have enclosed the Variety Selection chapter for their use. Again, I have no experience with many of the newer varieties listed, therefore always refer to the Virginia Soybean Variety Test results and other on-farm tests when selecting varieties. If you have not received you copies of the variety test results, please let me know.
Variety Selection
The 1997 Virginia Soybean Variety Evaluation Tests results (Publication 424-101) are available and most of the newer varieties, including Roundup-Ready varieties were tested. For many of the varieties, we have 2 years of data on their performance. Two-year means can be found in the report. On the other hand, very few varieties have been tested for three or more years. On the next page, I have summarized three-year average yields of those varieties that we have data. This is not necessarily a recommended list since many varieties that have not been tested for three years are also good performers. This list does however represent those varieties that we have very good confidence in their performance. I've also listed "relative yield." Relative yield is not a yield, but a value relative to all other varieties at a particular site. In other words, a variety with a relative yield of 105 was 5% higher yielding that the average of all varieties at that site. This somewhat "normalizes" the data and makes for easier comparisons. I would definitely recommend those varieties whose relative yields are 105 or higher.
Roundup-Ready Varieties
Herbicide-resistant varieties, especially the Roundup-Ready soybeans, are driving much of the variety selection this year. For an easy and effective weed control system, Roundup-Ready is hard to beat. However, there are still many other effective weed control programs out there. My suggestion is to use the Roundup-Ready varieties just like you would treat a nematode-resistant variety. If the field is infested with nematodes, then one should use a nematode-resistant variety. Likewise, if you have a weed problem that would warrant Roundup (perennial weeds, sicklepod, etc) or if you need to rotate herbicide modes of action (recommended to delay potential weed resistance), by all means utilize this new technology. But, do not just jump on the bandwagon because its what everyone else is doing.
In 1997, we extensively tested many Roundup-Ready soybean varieties.
Results can be found in the above-mentioned publication and are quite
interesting.
Under high yield potentials (in 1997, this was generally full-season tests),
maturity group (MG) III and IV Roundup-Ready varieties under-performed
conventional
varieties. On the other hand, under stressful environments and low yield
potentials (mainly double-crop, but some full-season tests also), the
Roundup-Ready
varieties performed as well or better than the conventional varieties.
Regardless
of yield potential, MG V Roundup-Ready varieties performed as well or better
than conventional varieties. Although the reason for the varying results
under different yield potentials is not yet clear, the trends were consistent.
In any case, there are some good performing Roundup-Ready varieties out
there and I am confident that yields are comparable with other varieties.
| Brand/Company | ||||
| Maturity Group III | ||||
| Full-Season | ||||
| Terra | TS 415** | 7 | 55.3 | 112 |
| Southern States | FFR-396 | 7 | 50.3 | 102 |
| Public | Bass | 10 | 45.4 | 97 |
| Maturity Group IV | ||||
| Full-Season | ||||
| Asgrow | A4341 | 16 | 48.8 | 111 |
| Southern States | FFR-439 | 16 | 46.2 | 105 |
| Dekalb | CX 445 | 12 | 47.1 | 104 |
| Public | Stressland | 16 | 45.2 | 103 |
| Double-Crop | ||||
| Southern States | FFR-439 | 10 | 32.2 | 107 |
| Public | Stressland | 10 | 30.8 | 103 |
| Maturity Group IVS | ||||
| Full-Season | ||||
| Mycogen | 470 | |||
| Hoffman | Hoff 7484 | |||
| Southern States | FFR-493 | |||
| Public | Chesapeake | |||
| Public | Manokin (nr)** | |||
| Terra | TS 474 | 12 | 45.9 | 100 |
| Dekalb | CX 478 | 12 | 46.1 | 100 |
| Terra | TS 4792 (nr) | 12 | 43.2 | 94 |
| Double-Crop | ||||
| Hoffman | Hoff 7484 | 8 | 36.1 | 101 |
| Southern States | FFR-493 | 10 | 33.2 | 101 |
| Terra | TS 474 | 8 | 35.4 | 99 |
| Public | Manokin (nr) | 10 | 32.3 | 98 |
| Public | Chesapeake | 10 | 29.8 | 90 |
| Terra | TS 4792 (nr) | 8 | 31.9 | 89 |
| Maturity Group V | ||||
| Full-Season | ||||
| Asgrow | A5545 (nr) | 14 | 48.1 | 107 |
| Public | Hutcheson | 17 | 46 | 107 |
| Public | Clifford | 17 | 45.9 | 106 |
| Deltapine | DP 3519S (nr) | 14 | 46.7 | 104 |
| Pioneer Brand | 9584 (nr) | 14 | 46.1 | 103 |
| Hyperformer | HY 574 (nr) | 14 | 45.5 | 102 |
| Public | Holladay | 17 | 43.1 | 100 |
| Hoffman | 3505 (nr) | 14 | 44.6 | 100 |
| Southern States | FFR-563N (nr) | 14 | 44.1 | 98 |
| Terra | TS 504 (nr) | 14 | 44 | 98 |
| Public | TN5-95 (nr) | 17 | 42.4 | 98 |
| Public | Accomac (nr) | 17 | 42.4 | 98 |
| Public | Wicomico (nr) | 17 | 41.6 | 97 |
| Public | Camp | 17 | 38.3 | 89 |
| Double-Crop | ||||
| Public | Clifford | 11 | 35.8 | 111 |
| Southern States | FFR-563N (nr) | 8 | 39.6 | 109 |
| Public | Hutcheson | 11 | 34.9 | 108 |
| Public | Holladay | 11 | 33.6 | 104 |
| Pioneer Brand | 9584 (nr) | 8 | 37.9 | 104 |
| Hyperformer | Hy 574 (nr) | 8 | 38 | 104 |
| Public | Wicomico (nr) | 11 | 33 | 102 |
| Hoffman | 3504 (nr) | 8 | 36.3 | 100 |
| Public | TN5-95 (nr) | 11 | 31.7 | 98 |
| Public | Accomac (nr) | 11 | 30.9 | 96 |
| Public | Camp | 11 | 27.4 | 85 |
| Maturity Group VI | ||||
| Full-Season | ||||
| Pionner Brand | 9692 (nr) | 9 | 46 | 104 |
| Public | Brim | 9 | 45 | 102 |
| Public | Dillon (nr) | 9 | 45 | 102 |
*Relative yield is calculated by dividing the yield of that variety by the average yield of all vareities at an individual site. A variety with a relative yield of 105 was 5% above the average of all varieties. Relative yield is not a yield, but a value relative to all other yield values.
**TS 415 is an early MG IV variety, but has been tested with MG III varieties.
***(nr) indicates nematode resistance.
Soybean Seed Treatments
Soybeans will occasionally require seed treatments of nitrogen-fixing bacteria, funigicides, and/or molybdenum. The situations in which each is needed and some precautions are described below.
Nitrogen-Fixing Bacteria. Soybeans are legumes and generally do not need to be fertilized with nitrogen. This is because of a symbiotic relationship with soil bacteria called Rhizobia. These bacteria attach themselves to the soybean root and form nodules. In exchange for nutrition derived from the soybean plant, the Rhizobia capture nitrogen from the soil air and provide most, if not all, of the soybean nitrogen needs. Do you need to inoculate the seed with the appropriate inoculant? Soybean nitrogen-fixing bacteria do not attach to other legumes, therefore will decline if soybeans are not being grown. However, these bacteria can remain in a field for 5 to 10 years after the last soybean crop. However, it is recommended that an inoculant be used if the field has not been planted to soybeans in the last three years. Otherwise, the soil will usually contain enough bacteria to produce a high-yielding crop. Inoculant is available as granular, liquid, and peat based. If needed, growers should purchase fresh inoculant dated for 1998 and should uniformly coat the seed.
A word regarding the effect of soil fungicides on the Rhizobia bacteria is needed. Certain fungicides are detrimental to rhizobia. Do not combine inoculants with the fungicides containing Captan or PCNB because these fungicides can harm the Rhizobia and reduce nodule counts, especially if you are growing soybean in a field for the first time. On the other hand, fungicides containing thiram, carboxin, or metalaxyl are generally safe to combine with the bacteria. If combining inoculant with any fungicide, the inoculant should be applied immediately before planting.
Seed Fungicides. Fungicide seed treatments can be used to reduce seedling disease and improve soybean stands. Generally, if the soil temperature is above 65 degrees, the seedling should rapidly emerge and a fungicide is not needed. However, if using soybean seed whose germination is between 75 and 85% or planting into cool wet soils, a fungicide may be warranted. Seed with a germination below 75% should not be used; seed treatments cannot make up for poor quality seed or of low germination. The following fungicides can be used to treat soybeans: captan, thiram, carboxin, PCNB, and metalaxyl.
Molybdenum. Molybdenum is a micronutrient required for nitrogen fixation. If in short supply, poor nitrogen fixation will occur. Most Virginia soils contain adequate molybdenum for plant growth, however that availability of molybdenum declines with pH. If the pH drops below 5.5, a molybdenum seed treatment can be justified. However, if soil pH is 5.5 or below, yield potential is very low due to other pH-related problems. Therefore, it is not recommended that molybdenum be applied unless soil pH approaches 5.5-5.8. A much better solution is to maintain pH at levels between 5.8 and 6.2.
Return to David Holshouser