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Issue No. 22, Article 5/September 24, 2010

Wheat Planting-Time Tips

After the "down" year in 2010, with reduced acreage and only average yields, prospects for the 2011 Illinois wheat crop are bright, with strong wheat prices and early harvest of the crops that wheat planting will follow this fall. Double-crop soybean yields will also be good in many places, adding to our optimism about wheat.

Here are some considerations as wheat planting time approaches:

  • In the most recent version of the Illinois Agronomy Handbook (pubsplus.uiuc.edu/C1394.html), we changed the listing of the Hessian fly-free date (HFFD)--considered to be the optimal time to plant for agronomic reasons even when the Hessian fly is not a threat--from date ranges by county to a map with six zones, each about 60 to 70 miles wide, from north to south in the state. Moving from north to south, the ranges for each zone (and the city or highway in about the north-south center of each zone) are as follows: September 17 to 21 (IL Route 72); September 21 to 26 (IL Route 17); September 26 to October 2 (U.S. Route 136); October 2 to 6 (I-70 in the east, IL Route 108 in the west); October 6 to 9 (U.S. Route 50); and October 9 to 12 (Marion).
  • The Hessian fly is typically rare in Illinois, but there is still risk--and little reward--for planting wheat much earlier than the HFFD. With a lot of corn and soybean already harvested, and with fresh memories of last year's very late (or prevented) wheat planting, the temptation to plant wheat early is considerable.

    The main concerns about planting too early are that, if warm temperatures continue through October, the crop will grow too large before dormancy. This can hurt winter survival and increase insect and disease problems. With soils reasonably dry in many areas now, normal rainfall won't cause much planting delay if we wait. It's also highly unlikely that planting two to three weeks before the optimum time will yield more than planting later. In fact, most research suggests that planting two to three weeks after the HFFD produces higher yields than planting two weeks before it.
  • As many have found, getting seed wheat this fall is challenging. This is the result of production problems this past year along with increased demand. Some producers, unable to find wheat seed, may turn to their own bins. Over time, the use of bin-run seed has been a losing proposition, and it is something we do not recommend. But if there is no other option, then make sure that any seed used is cleaned of diseased, lightweight, and broken seed and that it is tested for germination. Everyone also needs to obey the seed laws, which in the case of PVP (plant-variety protected) seed means that producers can keep seed only for their own use and may not make saved seed available to anyone else. Some companies may also have language on the tag or bag saying that a variety is patented and that seed may not be kept at all.
  • Plan to plant 30 to 35 germinable seeds per square foot, or 1.3 to 1.5 million seeds per acre. Seed sizes will vary from perhaps 10,000 to 15,000 per pound, so it will take as much as 130 to 150 pounds of seed per acre with very large seed to 100 pounds or less with small seed. If you don't know seed size but it looks about average, 100 to 120 pounds of seed per acre should suffice. If planting on time, you can stay toward the low end of the range.
  • Response to the use of seed treatment insecticide has been mixed, but it is greater in southern Illinois, and greater when planting early or on time, or when the weather stays warm to encourage fall growth. The main effect of this would be to kill aphids that land on the plants and can transmit viral diseases, especially barley yellow dwarf mosaic. The virus would have to be picked up by aphids from infected plants, and the fact that there is less volunteer wheat this year due to decreased acreage might reduce the number of infected plants to serve as reservoirs. But the risk remains.
  • With harvest of both corn and soybean relatively early in many places this year, some will have a choice of which crop to follow with wheat. Some advisors suggest strongly that wheat follow soybean instead of corn in order to minimize diseases that may carry over from corn. In research we have been doing recently at several Illinois locations, yield of wheat following corn has averaged about the same as following soybean. Tillage likewise has made little difference, so long as seed can be placed well and good stands result. Placing seed well into heavy corn residue can be difficult without tillage. It helps if planting is done when the residue is dry.
  • Wheat responds well to phosphorus, and it needs a small amount of N to make fall growth. Use DAP or MAP to provide 50 to 70 pounds of P, and the N in these materials should be enough for fall growth.

While things are pointing toward a good year and a nice rebound in Illinois wheat acreage, keep in mind that, as with any other crop, timely planting into good soil conditions, while a great way to start, doesn't guarantee high yields. It does increase the chances for the crop getting to spring in good shape, so it's critical to do this well. But weather during and after heading is still the major factor in determining wheat crop yields and quality.--Emerson Nafziger

Emerson Nafziger

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