Selecting Wheat Varieties and Seed Treatments for 1997-98
Crop and Soil Environmental News, September 1997
Daniel E. Brann
Wheat did well in another challenging year. Fall of 1996 was wet, December and January were cold and the crop developed slower than normal. February and March were much warmer than normal resulting in crops planted in a timely fashion getting ahead of schedule. April and May were much cooler than normal resulting in excellent tiller survival and kernal initiation. June was favorable for grain fill and harvest resulting in good yields of excellent quality. The unusual growing season affected performance of some varieties more than others.
The top yielding released variety over the past two years is NK-Coker 9663 with a two year state-wide average of 86 bu/acre followed by Jackson at 85 bu/acre. Pioneer Brand 2580 is the top yielder over three years. NK-Coker 9663 has excellent test weight, is taller than average with good but not excellent standability, and is later than average. It is moderately susceptible to powdery mildew. Jackson has excellent test weight, is later than average and moderate in height. NK-Coker 9663 and Jackson perform well where large amounts of straw are desirable or when the producer has a "stripper header". It may be desirable to use the growth regulator Cerone(r) on these varieties when fertilized to achieve their full yield potential or when a conventional header will be used following intensive management and straw will not be baled. Pioneer Brand 2580 is an excellent wheat variety for all levels of management and soil types. Test weight is average.
DynaGro 424, a new variety in the test this year, was the top yielding variety in the Coastal Plain Region and near the top statewide with an average of 81 bu/acre. It did exceptionally well at Painter, Loudoun, and Orange. These yields were obtained even though the variety is susceptible to powdery mildew. It has low test weight which may be a major concern in some years and some markets.
Another new variety that did quite well in the Coastal Plain Region was FFR 502W. It yielded less than average in the Piedmont and Blue Ridge Region. FFR 502W has excellent test weight, is truly earlier than average, shorter than average , and has good resistance to most major diseases. It will be interesting to evaluate the performance of this variety over years.
Other new varieties that performed well were NK-Coker 9134, and NK-Coker 9704. NK-Coker 9134 has excellent test weight, is taller and later than average. It is moderately susceptible to powdery mildew and wheat spindle streak. NK-Coker 9704 has excellent test weight, is earlier and shorter than average, and has good disease resistance.
Other relatively new varieties that offer good yields and special attributes include FFR 523W and Pioneer Brand 2691. FFR 523W is early and short but has only moderate test weight. Pioneer Brand 2691 is very early, short, and only moderate test weight. Both of these varieties should be planted on a timely basis but not early in the fall. Early planting may result in these varieties jointing in March.
The relatively poor yield performance of Pioneer Brand 2643 is related to reduced stand emergence of this variety at several locations and the fact that this variety does not tiller as much as most current varieties. Twenty seeds per row foot was not adequate for this variety this past fall when it was cold and wet after planting. Pioneer Brand 2684 was also thinner at several locations and did not perform as well in 1996-97 as it has in previous years in our test. Both of these varieties have performed at or above average over multiple years and in the Virginia Small Grains Yield Contest.
Trical 498 triticale continues to be a top-yielding variety. Yield performance of this variety gives the feed industry an opportunity to evaluate how to include it in poultry and swine diets.
The main seed treatment for years was Vitavax. Currently we have available Vitavax, Raxil, Baytan, Dividend, and others. The "best" seed treatment depends mainly on the susceptibility of the variety to powdery mildew, planting plans, and full season management plans. All labeled seed treatments will control smut.
Baytan or Dividend at 1.0 oz/100 lbs of seed are the only products that will reduce or control powdery mildew on susceptible varieties. Use of the above products is especially important when planting early to timely. Powdery mildew could affect fall and early winter vigor and, thus, reduce yields before a spring fungicide is applied. Research by Dr. Erik Stromberg, Plant Pathologist, Virginia Tech has shown that Dividend at the normal (0.5 oz/100 pounds of seed) rate gives only slight reduction in powdery mildew compared to fall, winter, or possibly season-long control of powdery mildew with Baytan.
Varieties that may respond well to Baytan seed treatment include NK Coker 9835, FFR 555, DynaGro 424, Hoffman 14, DynaGro 422, FFR 525W, and Saluda. It is more difficult to list varieties that will not respond to improved control of powdery mildew by Baytan since many varieties have been entered in the state test with Baytan (as shown by "-B" at the end of the name). Yield improvement with Baytan compared to no Baytan seed treatment can exceed 10 Bu/A, especially if timely fungicide is not applied in the spring.
The impacts of planting plans on seed treatment is related to time of planting and the type of seedbed prepared. Timely to early planted wheat is more likely to have fall-early winter mildew development than later planted wheat. Later planted wheat will not likely have mildew develop until March or April when foliar fungicides could be used effectively. The seedbed and planting equipment for wheat should enable a producer to plant wheat at 0.75 to 1.5 inches deep. Unfortunately, that is not always possible. Optimum seeding depth is more critical when seed is treated with Baytan than the other seed treatments since Baytan shortens the elongation of the coleoptile by about 25%. Baytan has been used effectively on millions of acres. It was used by two of the top three entries in the state wheat contest and all three entries in the no-till wheat yield contest.
The relationship between optimum seed treatment and full season management is related to whether a producer will scout the crop in the spring and apply fungicide - if needed. Producers that will not apply spring fungicide for powdery mildew should strongly consider using Baytan seed treatment on the varieties that were tested with Baytan or showed high ratings for powdery mildew.
The choice of fungicide seed treatment will have little or no impact on leaf rust, wheat spindle streak, barley yellow dwarf, pythium root rot, or glume blotch. Producers having a strong preference for certain seed treatments need to make their seed sources aware of that preference by August. For this year, seedsmen have already had to make the choice as they processed the seed. Evaluate seed treatment choices as the 1997-98 season progresses and relate your seed treatment preferences to seedsmen as early as possible in 1998.
Table 1. Yield performance of entries in the Virginia Tech Wheat Test, 1997 Harvest (bu/acre)
Table 2. Summary of performance of entries in the Virginia Tech Wheat Tests, 1997 Harvest