Soybean variety selection for 2005

MISSISSIPPI STATE, Miss. -- Soybean variety selection for 2005 has been nothing short of a challenge. Although wet fall weather affected many poplar varieties, the availability of some varieties is more of a recurring problem than it should be.

I wish one year someone would grow all they could sell of their top one or two most popular varieties. Not all of their product line, just one or two of the best.

When someone has a top performer, they should attempt to produce a larger-than-normal allotment. If they failed to sell the seed, they could move them out of the bin. (This is done routinely with cotton seed). This is not nearly as risky or expensive as some may have you believe.

There are tricks to growing high quality seed, but they are not difficult. When available supplies are short, I find myself questioning the patenting of seed. Inclement weather exaggerated this year’s problem, but if you hold a patent you need to meet demand.

Rapid adoption of the Roundup Ready technology has placed us in a vulnerable position. The technology has been good, but widescale reliance on Roundup Ready varieties has caused public varieties to diminish.

I saw more interest in conventional varieties this winter, and I am sure it is due to the recent price restructuring for Roundup Ready seed. I predicted years ago that it was all about the seed, not Roundup.

Conventional varieties are excellent rotation options. With the lack of use, however, having conventional varieties available is easier said than done.

If you feel this is important, support your foundation seed and breeding programs. We have several good programs, but they need support to stay the course. Arkansas has the most newly released conventional variety on the market, and there are varieties out of the USDA program at Stoneville, Miss., and the University of Missouri at Portagville, Mo.

Some state programs can develop Roundup Ready public varieties, but I doubt much difference will exist as far as seed cost. Any interest that might exist between Roundup Ready and conventional varieties is based entirely on seed cost.

Ford Baldwyn referred to the use of conventional varieties a couple of weeks ago in his Delta Farm Presscolumn. Conventional varieties offer opportunities to grow cheaper crops. Following several years use of Roundup Ready weed control, costs could be minimal.

Think about growing beans behind cotton. Cotton weed control programs are often weed-free in many fields. A crop of beans in this environment can encounter minimal weed control pressure. Conventional varieties rotated with Roundup Ready varieties would be similar.

As you make varietal choices, your biggest concern should be stem canker. It is impossible to predict if we will have a stem canker year, so you must be prepared. Many diseases can occur in any one year, but if you attempt to protect yourself against everything, yield is usually lacking.

The last two growing seasons have seen more stem canker due to heavy rains during early seedling development. Regardless of varietal susceptibility, we see less stem canker on Group 4s planted early, most likely due to their compressed growing season. Normally, Group 5s planted prior to late April will minimize the impact of stem canker, but last year, due to above normal rainfall, that date had to be mid-April or earlier.

When you plant Group 5s early, you hasten their maturity, similar to what we see with Group 4s. Rotation helps, but it will take two years out of beans to see any significant reduction.

The best insurance is varietal resistance. Several varieties have excellent resistance packages. Pay attention to numerical ratings conducted at Stoneville, Miss. Stem canker was first identified in Clay County, Miss., in 1973. Having a long history appears to have allowed Mississppi to have a more virulent strain.

I believe this is the case because varieties that fare well in other states are more susceptible here. In additional, susceptibility is greater in the hills than in the Delta.

The ratings represent plants that have been toothpick-inoculated. This may be a worst-case scenario, but following the ratings should keep you out of trouble. The numeric ratings range from 1 to 5. Letter ratings are available also, but the numeric scale does a better job of separating differences.

With soybean rust looming on the horizon, we must stay focused and be prepared. We do have foliar fungicides to keep rust in check. Fungicides are not an option with stem canker.

Under the right conditions we have two diseases that can be potentially as severe, if not worse than rust: stem canker and charcoal rot. Resistant varieties, earlier-maturing varieties, early planting and crop rotation will all help.

In the case of charcoal rot, from time to time I hear comments about varietal differences, but this has yet to be documented. The best control of charcoal rot is to minimize stress by the use of tillage (on some soils), irrigation, proper fertilization, adequate pH, early planting, and any other practice that helps the plant avoid extremes.

Variety selection this winter has been difficult to say the least. Due to shortages, many will plant varieties they have never grown before, but this is mainly due to the wet fall and its effects on seed quality. Group 5 supplies are tight, increasing pressure on Group 4 supplies.

If you find yourself short of desired varieties, turn this into an opportunity. Plant several different new varieties to spread your risk. It is possible a new promising variety could surface. We have enough seed, just not enough of the top performing varieties.

This is not the year to take unnecessary risks. Plant your highest quality seed first. Use the proper seed treatment and keep replants to a minimum due to seed availability.

Alan Blaine is the Mississippi Extension soybean specialist. e-mail: [email protected]

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