Index

• Soybean Variety Selection
• Soybean Exports Up
• Ask the Specialist
• Top Yielding Soybean Varieties for 2000
• American / Virginia Soybean Association Issues

Soybean Variety Selection

Many soybean producers have already made their variety selections and I hope information delivered to them at local Cooperative Extension meetings were of help. Still, with all of the available varieties, it is difficult to determine whether or not the right choice is being made. Virginia Tech annually conducts 12 replicated soybean variety tests in six regions of Virginia. While it is valuable to use the results of the test closest to your operation, generally a good variety will perform well in all locations. Therefore it is advisable to look at average yields across locations in addition to selecting varieties based on local yield data. On the following page are a list of soybean varieties that have consistently performed well across all locations. This selection was based on relative yields, which is yield of a variety compared to the average yield of all varieties at that test site and year. Still, one must not base their selection only on yield. Maturity, nematode and herbicide resistance traits need consideration.

Chose the proper maturity

ESPS is not the answer in Virginia

Which maturity group?

Develop adequate leaf area for double-crop systems

In general, we can back off the full-season recommendations by about _ of a MG. Don't use late- MG 5 or MG 6 due to frost concerns in any part of Virginia. In the northern Piedmont and Valley, don't use an early or late MG 5. Many of the reasons that some MG 5 varieties perform well in full-season tests in Virginia and not double-crop test has to do with their later relative maturity. However, use the latest MG possible to maximize leaf area and yields. In eastern and southern Virginia, an early MG5 will on average out-yield a MG 4 when planted double-crop. But this is not always the case.

Soil type matters

Nematode and Herbicide Tolerance

Determining whether to use a herbicide-tolerant variety is usually easier than determining to use a nematode-tolerant variety. Weeds are much more visible from the end of the road. Still, most of us can recognize a nematode infested field near the end of the growing season, although we may not know the problem is nematodes. In many cases, these fields look worse that a weed-infested field and may be just as yield robbing. Therefore, test the soils for nematodes if you suspect a problem. Fall is the best time to do this because nematode populations usually fall dramatically during the winter. Yet, spring is not too late to sample. One thing is for sure. If you have high spring counts, then you definitely need to address the problem.

Of course, the first line of defense is rotation to a non-host crop. If cyst nematode is a problem, then rotation to any crop is effective. However, is root knot is the problem, then its not as easy. Northern root knot can use corn and cotton as an alternative host, but southern root knot only uses peanut as a host. Regardless, if soybeans must be planted select the appropriate variety. Unfortunately, with the exception of soybean cyst nematode, little is known about the resistance of soybean to other nematodes. The table that follows lists those varieties with soybean cyst and root knot nematode resistance.

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Soybean Exports Up

Although soybean prices are still not good, last month's USDA crop report indicated that soybean export prospects for 1999/2000 are up 20 million bushels to 910 million bushels. Higher Chinese import prospects and lower Indian soybean meal exports are supporting this. Soybean oil exports were lower, but were offset by more domestic use. Therefore projected U. S. soybean producer prices are $4.50 to $4.90 per bushel. The reason for the low prices is still production. U. S. soybean acreage will be high again in 2000. It seems that South America will again produce a large crop with Argentina producing its largest crop ever.

Still, with use and exports increasing, prices should have bottomed out and better prices should be ahead in future years.

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Ask the Specialist

Do you recommend planting maturity group 3 varieties in Virginia?

The answer to this question can be found in this newsletter in the Soybean Variety Selection discussion. But, for most of Virginia's acreage, I do not. Yield and seed quality problems can arise with full-season plantings. In double-crop plantings, there generally isn't enough time to produce the needed leaf area to maximize yield.

However, there are situations in which MG 3 varieties may be of some use and benefit. In the Shenandoah Valley and Northern Piedmont, they do fit well due to the shorter growing seasons in these regions. If one is interested in continuous double cropping and barley planting is following the soybean harvest, the MG 3's are necessary for timely planting of the small grain crop. Another situation would apply to a cotton, corn, and soybean farmer who would like to harvest part of their soybean crop between corn and cotton harvest. In order to do this a MG 3 or early 4 may be necessary. In summary, MG 3 varieties may fill a niche, but are not recommended in most Virginia situations.

In your leaf area index presentations, you said that soybean plant type (bushy, intermediate, or thin) did not affect the leaf area index as much as row spacing and plant population. You also indicated that soybeans planted full-season usually would obtain adequate leaf area regardless of row spacing, plant population, or variety. Is this the case for wide rows (> 20 inches) as well?

Excellent question! In my presentations, I probably failed to emphasize that I was speaking of soybean planted in narrow (<20 inch) rows. In general, I do not recommend planting soybeans in wide rows because of the yield advantage of narrow rows. However, I realize that the yield advantage may not, in some situations, justify buying a new planter or converting an existing planter to narrow rows. The overall profitability of an individual's operation may be better with wide rows for all crops.

With this in mind, variety selection would likely be very important if planting in wide rows. For instance, in 36-inch rows, one should benefit by planting a bushy variety that branches profusely. An example of a big, bushy variety is the public varieties Hutcheson and Accomac. Seed company variety information guides usually list the plant type of the variety. A bushy variety tends to fill in for gaps as well. Therefore, if stand is a perennial problem, then selection of this type of variety may be beneficial.

Keep in mind, that the idea of leaf area index is to produce approximately 3.5 to 4.0 acres of leaves per acre of land. Adding more leaf area than this will not further increase yield. Therefore, full-season systems generally have time to produce this amount of growth. The necessary growth in double-crop systems can be achieved by narrowing the row spacing and increasing the plant population.

Another aspect of producing the needed leaf area is soil type. Soils with high water-holding capacity can be very forgiving and generally respond less to narrow rows and increased plant population. However, less productive soils depend more heavily on these cultural practice adjustments. Therefore, keep the row width to 20 inches or less and adjust the seeding rate based on planting dates as recommended.

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Top Yielding Soybean Varieties for 2000

The list below contains those soybean varieties that have yielded more than average of all varieties tested in multiple locations in 1997-99. For more detailed information, refer to Virginia Tech Publication 424-101, revised in 1999. Unless specified, the varieties listed have been tested in at least 6 locations for at least two of the past 3 years.

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Sincerely,

David L. Holshouser

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