Number 112 October 26, 2007

Transcription

1 Number 112 October 26, What to do with thick stands of volunteer wheat 1 2. Effect of freeze damage on Foundation Seed wheat seed supplies and production _ 2 3. La Nina and drought in Kansas 6 1. What to do with thick stands of volunteer wheat Thick stands of volunteer wheat have emerged in parts of central Kansas in recent weeks on fields that were abandoned during the summer. In general, there is less volunteer where the stubble and residue were burned, and more where the fields were disked. Abandoned wheat fields in many cases had 2 to 3 bushels per acre of grain, or more, in the heads. Much of this grain has now germinated as volunteer, and the resulting stands are too thick to make a grain crop next spring. Stands this thick will almost surely burn up before heading. How thick is too thick? Anything over about 50 plants per square foot, counting both the planted wheat and volunteer wheat if the two have emerged together. Here s the math that goes into that calculation: A normal seeding rate of 60 lbs per acre, using a variety that has 15,000 seeds per lb, results in about 900,000 seeds per acre. At 80 percent germination/emergence, that is 720,000 plants per acre, which comes out to plants per sq ft. Wheat planted at this rate normally has about 2.5 tillers per plant (including the main tiller), which means there are about 40 heads per square foot at the end of the season. If you used a higher seeding rate, there would be fewer tillers per plant, and the number of heads per acre comes out about the same at the end of the year. If there are already plants per square foot present, that is getting close to the upper limit of what can be sustained in most situations in Kansas. Remember, wheat normally start out at about plants per sq ft, and gradually tiller out through the season until there are about 40 heads per sq ft by the end of the season. If the stand starts out with 40-1

2 50 plants per sq ft in the fall, the soil moisture supplied is depleted early, and the chances of the crop surviving the spring and summer diminish. If there are 50 plants per square foot at this time of year, that s equivalent to a seeding rate of about 180 lbs per acre, or 3 bushels per acre. That kind of a stand usually burns up in Kansas. Anything more than 50 plants per square foot has almost no chance of surviving to heading. Not every situation with thick volunteer should be treated the same at this time. There are three main situations to consider: * The thick volunteer is growing on a field that has not yet been planted to wheat. It s getting late, but there is still time to kill the volunteer before planting wheat. That should be done as soon as possible. If left alone and not planted to wheat, that field will have value only as a forage crop. * The volunteer has come up in a field in which the wheat has already been drilled, and there is a total of more than 50 plants per sq ft in the fall. This is the worst possible scenario. If there is enough seed available, the best approach is to destroy the stand and re-seed if the producer is after grain yield. With an early November planting date, yield potential may be reduced by 20 percent, but that s better than leaving the overly thick stand and ending up with nothing. If there is no seed available, producers could try to thin out the stand with some type of cultivation or tillage implement somehow. This may still leave the stand too thick, however. If none of those options is feasible, the stand could be used for graze-out, hay, or silage, then planted back to a row crop next spring. Thick stands can produce quite a bit of forage, and this approach can be profitable. * The volunteer has come up late and thick in a field that will not be planted to wheat, but is adjacent to a field of planted wheat. In this case, control is optional. If the volunteer emerged about the same time as planted wheat, then it poses no special risk of wheat streak mosaic or any other problem associated with volunteer that comes up early in the summer. Finally, what if the late-emerged volunteer is not too thick? There may be some cases where the stand of volunteer plus the drilled wheat is less than 50 plants per sq ft. In this case, the best approach is to do nothing. More volunteer may come up later this fall or winter and make the stand too thick, but that s unpredictable. -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu 2. Effect of freeze damage on Foundation Seed wheat seed supplies and production 2

3 The early April freezes this year affected almost every aspect of wheat variety performance in central and eastern Kansas, from breeders plots and experimental line increases to farmers production fields. Foundation seed production was affected, as well, although we produced enough seed to plant our normal acreages this fall. All Foundation seed had a test weight that exceeded 56 pounds per bushel in In a typical year, Foundation Seed will plant about 120 acres of a variety that has good demand. We use a seeding rate of 40 pounds per acre, and plan on producing about 3,500 to 5,000 bushels per year of such varieties. The exact amount we plan to plant and produce of a given variety in any one year depends on the amount of carryover seed we have of that variety and the demand we anticipate. We produce most of our hard red winter wheat Foundation seed at one of four locations in the state: Manhattan, Hutchinson, Hesston, and Ottawa. Last season, all of these locations were hurt by freeze damage. Three of the sites had severe freeze injury. The Foundation seed fields in Manhattan had the best yields and quality, and saved the seed supply in some cases. Besides Manhattan, some hard red winter varieties adapted only to western Kansas are maintained in Colby, but that is just a small percentage of the overall production. It is unusual for central and eastern Kansas to have such a widespread wheat crop failure, which is why we concentrate most our seed production fields in those areas. In 2007, that worked against us. Our hard white wheat Foundation seed production is at Hays, which also had some freeze and hail damage in We are currently maintaining Foundation seed of 2137, 2145, 2174, Danby, Endurance, Fuller, Jagger, Karl 92, Overley, RonL, and various experimental wheat lines. Here is the Foundation seed supply situation for each of these varieties: Acreage planted fall of 2006: 30 Production in 2006/07 crop year: 1,000 bushels Supply and demand for Foundation seed in fall of 2007: Demand greater than supply. Comments: Acreage of 2137 had been declining in Kansas for several years, and we did not anticipate the strength of demand for this variety for this fall. We still anticipate lower demand for 2137 than for Fuller and Overley, but plan to maintain our production at 30 acres this fall Acreage to be planted fall of 2007: 0 3

4 Supply and demand for Foundation seed in fall of 2007: Adequate supplies to meet demand for Foundation seed. Comments: In the 2005/06 crop year, 2145 had very good yields. Because of that exceptional production, a large amount of carryover 2145 was available in the fall of 2006 and no Foundation seed acreage was planted that year. There is still a very good supply of carryover Foundation seed in the fall of 2007, so no new acreage will be planted again this fall Acreage to be planted fall of 2007: 0 Supply and demand for Foundation seed in fall of 2007: Adequate supplies to meet demand for Foundation seed. Comments: Probably the last year Foundation Seed will carry this variety. Danby. Acreage planted fall of 2006: 30 Production in 2006/07 crop year: 1,140 bushels Supply and demand for Foundation seed in fall of 2007: Adequate supplies to meet demand for Foundation seed. Comments: None. Endurance. Supply and demand for Foundation seed in fall of 2007: Tight. Comments: Demand has been surprisingly strong in Kansas this fall, but it s uncertain how strong that demand will be in the future. Fuller. Acreage planted fall of 2006: 120 Production in 2006/07 crop year: 2,600 bushels Acreage to be planted fall of 2007: 120 4

5 Supply and demand for Foundation seed in fall of 2007: Demand exceeded supply by about four to five times. There was no Foundation seed of Fuller in reserve going into last season, and we produced only 2,000 bushels because of freeze injury. Most of the seed produced was in the fields at Manhattan. Comments: Maximum effort will be put into increasing Foundation seed supplies this year. Even with good production, we anticipate having no reserve supplies by the fall of Jagger. Acreage planted fall of 2006: 80 Production in 2006/07 crop year: 1,100 bushels Acreage to be planted fall of 2007: 70 Supply and demand for Foundation seed in fall of 2007: Demand exceeded supply. Comments: A good level production will be maintained, as carryover supplies are now gone due to the high demand this fall. Karl 92. Acreage to be planted fall of 2007: 32 Carryover supplies as of fall 2007: 0 Supply and demand for Foundation Seed in fall of 2007: Tight. Comments: Acreage of Karl 92 had been declining in Kansas for several years, and we did not anticipate the strength of demand for this variety for this fall. Overley. Acreage planted fall of 2006: 120 Production in 2006/07 crop year: 3,000 bushels Acreage to be planted fall of 2007: 120 Supply and demand for Foundation Seed in fall of 2007: Supply exceeded demand by two to three times. Comments: All of the Foundation seed production of Overley in 2006/07 was in Manhattan, which was fortunate since that site had less freeze injury than the other three sites we typically use. Still, demand exceeded the amount we produced and the amount we had in reserve as carryover. We will continue to maximize production of Foundation seed of Overley for the foreseeable future to meet demand and rebuild carryover supplies. RonL. Acreage planted fall of 2006: 30 5

6 Production in 2006/07 crop year: 1,080 bushels Supply and demand for Foundation Seed in fall of 2007: Adequate supplies were available. Comments: None. -- Vernon Schaffer, Kansas Foundation Seed 3. La Nina and drought in Kansas Last year at this time, and El Nino event had become established in the Pacific Ocean. During El Nino years, precipitation in Kansas during the December-February period is usually above normal, and that s what happened in 2006/07. This year, the opposite situation has occurred. A strong La Nina event is currently set up in the Pacific Ocean. During years when the onset of La Nina began in the fall, precipitation in Kansas during the December-February period is usually below normal. While understanding that no two events are the same, here are the December-February precipitation records of some recent years in which La Nina occurred. Dec-Feb Precipitation Comparisons of Normal and Fall-Onset La Nina years Years Departure from average average fall-onset La Nina fall-onset La Nina fall-onset La Nina year fall-onset La Nina average Western Kansas Dec-Feb Precipitation Comparisons 3-year fall-onset La Nina average State Division average Dec-Feb precipitation Departure from average Northwest West Central Southwest

7 Central Kansas Dec-Feb Precipitation Comparisons 3-year fall-onset La Nina average State Division average Dec-Feb precipitation Departure from average North Central Central South Central Eastern Kansas Dec-Feb Precipitation Comparisons 3-year fall onset La Nina average State Division average Dec-Feb precipitation Departure from average Northeast East Central Southeast Mary Knapp, State Climatologist These e-updates are a regular weekly item from K-State Extension Agronomy and Steve Watson, Agronomy e-update Editor. All of the Research and Extension faculty in Agronomy will be involved as sources from time to time. If you have any questions or suggestions for topics you'd like to have us address in this weekly update, contact Steve Watson, swatson@ksu.edu, or Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu 7