High wheat yields possible in south Georgia

It is possible for growers in south Georgia to average 100-plus bushels of wheat per acre, says Eddie McGriff, Extension coordinator in southeast Georgia’s Coffee County.

“Growers should be aiming to average at least 60 to 80 bushels per acre, and with excellent growing and harvest conditions, 80 to 100 bushels,” says McGriff. “Growers have an excellent opportunity to grow 80-plus bushel wheat with intensive management.”

McGriff and University of Georgia Extension agronomist Dewey Lee have put together the following list of 10 critical management inputs for high-yield wheat production:

1) Use deep tillage to disrupt hard pans. Wheat responds well to deep tillage when hard pans are present in soils. Soils should be prepared for planting by first tilling with a V-ripper, chisel plow, paraplow or subsoiler. Firm the seedbed with a cultipacker or small, light disk to reduce deep ruts from planting. Till the soil only to a depth necessary to break the hard pan. Simple disking is not as effective as deep tillage but is preferred over no-tilling wheat. No-till wheat can be productive (mostly on heavy, clayey soils), but the yields, in general, are five to 25 bushels per acre less than conventionally tilled wheat.

2) Plant high yielding, pest-resistant, well-adapted varieties. Yield data for all the recommended varieties for Georgia are found in the current 2007 Georgia Wheat Production Guide or at http://www.swvt.uga.edu/. Variety characteristics are noted in the production guide. Be sure to note variety characteristics such as vernalization, maturity, lodging resistance and pest resistance so you can manage properly for the highest yield. Seed supply is extremely short in 2007. There are many varieties currently offered for sale in Georgia that are better adapted for the Mid-South (Missouri, Arkansas, Tennessee, etc.) and have not been tested in Georgia. Check with your Extension office for the latest information on these varieties. While some may perform to satisfactory levels, others have characteristics that may be too difficult to overcome with good management.

3) Plant the appropriate seeding rate for your planting method. Wheat can be successfully established by either drilling or broadcasting the seed and incorporating into the soil to a shallow depth. In general, drilled wheat will have yields 7 to 8 percent higher than broadcasted wheat. If incorporation of broadcast seed is poor, then yield differences are even greater. In a drill, seed wheat planting 18 to 22 seeds per row foot (7.5-inch drill width). This is equivalent to approximately 30 seeds per square foot. Use 10 to 15 percent more seed when planting after the recommended planting window. Wheat emerges best when planted 1 to 1.5 inches deep. When broadcasting the seed, calibrate the equipment to plant 40 seeds per square foot. When possible, always use high quality, certified seed and save a tag of each separate lot for good record keeping.

4) Plant during your recommended planting period. The recommended planting dates for Georgia are the seven days prior to and after the five-year average first frost day for your farm. Varieties with long vernalization requirements should be planted in the first seven to 10 days prior to the first frost day. Generally, Coffee County’s first frost day will be in late-November. In 2005 it was Dec. 3 and in 2006 it was Nov. 26. Other counties can check out www.GeorgiaWeather.net for help in determining your first frost date.

Due to the short seed supply in 2007, many Mid-South varieties have been sold for planting in Georgia. These must be planted in the first few days of the recommended planting window to provide the best opportunity for proper vernalization. Extremely early varieties with short vernalization requirements such as Fleming must be planted in the very last days of the recommended window. These varieties can suffer winter injury if planted too early.

5) Scout fields for early insect infestations and control potentially damaging insects. Hessian fly and aphids are the two insects that can cause yield loss in the fall. These insects can be controlled by either planting resistant varieties and or using an approved insecticide. Protect wheat from Hessian fly by planting resistant varieties or treating seed either with Cruiser (thiamethoxam) or Gaucho (imidacloprid). See the Georgia Pest Control Handbook for proper rates. These seed treatments are also effective against aphids. Aphids vector the barley yellow dwarf virus and it is important to protect wheat from this virus. For both insects, scout wheat fields 25 to 35 days after emergence for the presence of either aphids or Hessian fly. Apply an approved pyrethroid insecticide if either is present and no seed treatment has been used. Again, scout just prior to top-dressing. If aphids are present, then combine insecticides with the nitrogen fertilizer to prevent spring infestations. Thresholds and rates are listed in the Pest Control Handbook and Wheat Production Guide.

6) Control weeds early to prevent yield loss. Control ryegrass, wild radish, wild turnips, onions, garlic, henbit, chickweed and vetch early for maximum weed control efficiency and high yield. Waiting to control these weeds until the spring causes considerable yield loss due to lost tillers and reduced herbicide effectiveness. Scout wheat 25 to 35 days after emergence and note any weed infestations. Broadleaf weeds should be controlled when they are small (such as 2 to 4-inch wild radish). Products such as Express or Harmony Extra are preferred due to their effectiveness and a large window of safe application. Do not apply 2, 4-D on wheat that is not fully tillered or injury will occur. Also, do not apply 2, 4–D to wheat beyond the first hollow stem phase or injury will occur. Ryegrass should be controlled when it is between the two-leaf to two-tiller stage. Products such as Hoelon, Axial and Osprey are very effective. Osprey also has some activity against small broadleaves. For residual control of ryegrass, tank mix 1.5 pints of Prowl H2O with your postemergence herbicide. Prowl must be applied to wheat that is established and growing. See the Georgia Pest Control Handbook or Wheat Production Guide for rates and timing information.

7) Soil test and apply all nutrients according to recommendations for high yield. Wheat should be planted in soils that have a pH of 6.0 to 6.5. If fertilizing for the wheat crop only, apply all phosphorus and potassium in the fall during seed bed preparation according to soil test recommendations. If applying nutrients for the subsequent crop such as soybeans, apply one-half of the potash in the fall and the remainder during the spring at top-dressing. Nitrogen should be used in the fall to encourage tiller production prior to the onset of winter. It is important not to over-fertilize with nitrogen as it may cause excessive growth and result in winter injury. In general, apply nitrogen as follows plus 3 to 5 pounds per acre of sulfur (based on the previous crop rotation):

Cotton: 35 to 40 pounds per acre.

Corn: 30 to 35 pounds per acre.

Fallow: 25 to 30 pounds per acre.

Soybeans and peanuts: 15 to 20 pounds per acre.

If using poultry litter, obtain a nutrient analysis so as to adjust the rate of application according to the nutrient content. In general, 2 tons per acre is sufficient for fall growth. Applying more may increase risk of excessive growth and winter injury. Also, if chicken litter is applied too close to planting wheat, nitrogen may not be available for good early growth, so nitrogen should be applied to supplement good early growth (usually 15 to 20 pounds of nitrogen is sufficient).

8) Top-dress wheat with nitrogen in a timely manner in late winter and early spring. During the later days of January, begin counting tillers to determine the need for additional nitrogen applications for the proper tiller production. If tiller counts (a stem with at least three leaves) exceed 80 or more per square foot at Zadoks GS 25, then apply all remaining nitrogen with 10 pounds per acre of sulfur at GS 30 (stem elongation). Usually this occurs during early to mid-February.

If the tiller count is less than 80, then apply 30 to 40 pounds of nitrogen with 10 pounds of sulfur per acre to encourage tiller production prior to the onset of stem elongation. Complete the top-dressing prior to first node stage.

Nitrogen rates will vary according to the soil type, variety lodging resistance, irrigation capability, previous crop, etc. In general, total nitrogen rates range from 100 to 120 pounds per acre with 10 pounds of sulfur per acre (increase sulfur rate to 15 to 20 pounds per acre if soils are sandy). Tank-mix an approved pyrethroid if aphids are present to reduce the risk from barley yellow dwarf virus.

9) Scout fields for the onset of diseases. Powdery mildew, stripe rust, leaf rust and leaf and glume blotch are diseases that can be controlled with an approved fungicide application. Begin scouting fields when the plant reaches GS 32-37 (Feekes GS 7-8).

In general, powdery mildew and stripe rust will likely appear first. If no disease is present by GS 58 (Feekes 10.5) but expected, then apply the proper rate of Tilt, Quilt, Stratego, Headline or Quadris to maintain the high yield potential and test weight.

See the Georgia Pest Control Handbook or Wheat Production Guide for rate and timing information.

10) Harvest as early as possible. Soft red winter wheat easily sprouts when the grain is exposed to rainy conditions after maturity. Harvest the crop as soon as possible to avoid field losses and to maintain good quality grain. Dry the grain if harvesting above 15-percent moisture.

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