Straight From the Horse's Mouth

Duane A. Lienemann, UNL Extension Educator, Webster County September 2, 2009 Edition Producers are finishing up their irrigating season, some have already picked up pipe and all are preparing for the fall season. Part of that is because of how the weather feels, but mostly by the calendar. It will not be long and our area farmers will be busy preparing for the 2010 wheat crop. With the type of year we have experienced and the problems in wheat fields we have seen in the past in our area, I think that like never before it is crucial to follow the recommended guidelines to insure a productive and successful crop. Let’s take a look at some things we should be doing in this session. First, let’s look at the potential for disease and what we can do about it. Believe it or not, Fall is the best time to prevent wheat disease problems from robbing yields next spring. How can that be? Well, variety selection is the single most important factor in disease management and many producers are looking at what seed wheat they will be planting in the next few weeks. Although no variety is resistant to everything, modern varieties have much better resistance to diseases and insects than those from a decade ago. The 2009 Nebraska Fall Seed Guide is available in your local Extension Office at a minimal cost or if you have access to the internet there are some very good places you can go. You can go for a “Virtual Tour of Nebraska Wheat Varieties” by going to: http://www.panhandle.unl.edu/wheat/index.html or additional on-line information on wheat varieties can be found at http://varietytest.unl.edu/winterwheat.html . A fairly new tool for wheat variety selection for the area, UNL Extension Winter Wheat Variety Selection Tool, can be found at: http://citnews.unl.edu/winter_wheat_tool/index.shtml. Since we in South Central Nebraska have a lot in common with North Central Kansas I might also suggest utilizing the Kansas State wheat varieties and test results web site at: http://kscroptests.agron.ksu.edu/. You can also get a lot of good information at: http://wheatbook.unl.edu/ . No matter which variety of seed wheat you select, I absolutely suggest using cleaned and conditioned Certified and treated seed that has a high test weight (56+). All of these qualities increase the success with winter wheat. The seed treatments need to thoroughly coat the seeds to give good results and should be applied with seed treating equipment. If you treat it with a fungicidal seed treatment (e.g. Dividend Extreme, Raxil-Thiram, or RaxilXT) it can reduce the risk of problems later on. I have a list of treatments that you can use. Please contact me if you are interested. It isn’t only seed varieties that can have an effect on disease and insects, there is no doubt that planting date has a strong impact on several diseases and insects. Early planting is a risk factor for wheat streak mosaic, barley yellow dwarf, take-all root rot, and of course Hessian Fly. To minimize risks, I suggest that you plant after the Hessian fly free date which is September 25 for South Central Nebraska. So from then up to two weeks after that date would be the optimum planting dates. If you get late in planting, the seed rate should be increased to compensate for the lack of tillering associated with that delayed planting. Use a seeding rate of 90 lbs/- 120 lbs/acre in rain fed row crop fields. Wheat can emerge from various depths, but a planting depth of 1 to 2 inches is optimal. If deeper planting is necessary, producers should be aware of the coleoptile length of the variety to be planted. They should also be aware that soil temperature also has a big effect on coleoptile length. Extension reseach shows that maximum coleoptile elongation of a variety is influenced heavily by soil temperature. As soil temperature decreases from 65 degrees, coleoptile lengths of semi-dwarf varieties actually increase in length, however when soil temperatures are below 65 degrees, the coleoptile length of all varieties will be similar. There are always other key questions that producers have regarding recommendations to help with the wheat cropping enterprise. Let’s take a look at a couple of the most popular. How can I determine the amount of N (nitrogen) or P (phosphorus) to add for my wheat crop? Soil testing is the backbone of any well-designed fertility program. So starting with a soil test is a must. Soil core should be taken 6 to 8 inches for phosphorus and if possible 24 inches for nitrogen. When seeding wheat late, phosphorus placed with the seed helps improve yield. Use 20 pounds phosphorus where none is called for by soil tests and increase other phosphorus rates which are over 20 pounds by 20% for late seeded winter wheat. How much N does a bushel of wheat require? Nitrogen requirements for wheat are directly related to yield potential. Hard red winter wheat with a protein content of 12.5% will require about 2.4 pounds of available N per bushel. One factor that has increased the need for wheat N fertilization is the gradual decline in soil organic matter levels. In general, wheat will need about 20 to 40 lbs/acre more nitrogen when double-cropped into sorghum residue than when double cropped into soybean or corn residue to make equivalent yields. This is especially true if the wheat will be no-tilled or the sorghum plants are still alive when the wheat is planted. What varieties are best for continuous no-till wheat? This question comes up quite frequently and there has been almost no research done that tests variety performance under no-till, continuous wheat conditions. The best single criterion to use in selecting varieties for no-till continuous is tan spot resistant so look for varieties with high resistance. Other traits that are important for no-till continuous wheat are strong emergence and early growth, Hessian Fly resistance and septoria leaf blotch resistance. The preceding information comes from the research and personal observations of the writer which may or may not reflect the views of UNL or UNL Extension. For more further information on these or other topics contact D. A. Lienemann, UNL Extension Educator for Webster County in Red Cloud, (402) 746-3417 or email to: dlienemann2@unl.edu