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Spring Crop Tour at the K-State Experiment Station

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Lucas Haag, K-State Northwest Area Agronomist, discusses the wheat varieties during the Spring Crop tour.

Story Photo

Lucas Haag, K-State Northwest Area Agronomist, discusses the wheat varieties during the Spring Crop tour.

By: Jeanne Falk Jones, K-State Multi-County Agronomist
The K-State Spring Crop Tour was held on Wednesday, June 9 at the K-State Southwest Research and Extension Center in Tribune. Dr. Alan Schlegel, Agronomist-In-Charge, welcomed everyone to the Tribune station and gave a brief overview of the growing season. The attendees and K-State agronomists loaded onto a trailer and made stops at the wheat performance test, a corn study looking at date of planting and maturity and at a study on occasional tillage as compared to no-till conditions. 
The first stop on the tour was at the corn study looking at the date of planting and maturity of the hybrids. Dr. Lucas Haag, K-State Northwest Area Agronomist discussed this research. There are five planting dates that extend from mid-April until mid-June. There are nine hybrids included in the study. The hybrids are grouped, with three early maturing hybrids (99-101 day), three mid-season hybrids (105-108 day) and three late season hybrids (112-118 day). There are several factors being measured in this research, including growing degree units (GDUs) to critical growth stages, water use and grain yield. For GDUs to emergence, most textbooks will tell you that it ranges from 90 to 100 GDUs. However, in this research at Tribune in no-till conditions, the GDUs to emergence ranges on average from 172 to 270. This is likely related to the higher amounts of residue, in which the corn is being planted. When looking at corn yields over 3 years of the study at Colby and Tribune, the results show there is not a great deal of yield decrease by planting after June 1. Therefore, the planting window is fairly wide, with planting in early-June being seldom worse than early-May. In addition, the short season hybrid group seldom had a yield advantage in any environment. The short season group often left yield on the table, even at early or mid-June planting dates. Haag also referred to the ‘planting date x maturity probability tables’ as a reference for farmers when corn planting extends later into the spring. These tables show a worst-case scenario on how likely a corn hybrid will reach black layer prior to a killing frost in the fall. These tables can be found at www.northwest.ksu.edu/agronomy.
Also at this stop, K-State Extension Entomologist Anthony Zukoff discussed changes, proposed by EPA, to Bt corn guidelines. Currently farmers can purchase Bt corn as a ‘refuge in the bag’. This puts non-Bt corn hybrid plants intermixed with Bt hybrids and this allows them to cross-pollinate. Therefore, corn kernels express different levels of the Bt protein. Because of this, the corn earworm and other ear feeding pests may be exposed to less than lethal levels of the Bt protein and resistance has developed to some Bt proteins. There are several proposed changes to help combat this. One is increasing the amount of non-Bt kernels in a bag from 5% to 10%. In addition, a proposed change is to phase out hybrids with single proteins to ensure all Bt hybrids have 2 or more effective Bt proteins. Another change is to have sentinel plots across the corn and cotton growing areas to screen for resistance to the Vip3A Bt protein. These are just proposed changes, but Zukoff wanted farmers to be aware of them. He said it is possible we will see some form of these guidelines being instituted over the next several years. 
The second stop on the Spring Crop Tour was at the wheat performance test. This test contains over 30 varieties and is replicated. That means each variety is planted five times in small plots throughout the study to help account for any variability across the plot. There are wheat varieties from Kansas State University (Kansas Wheat Alliance), Colorado State University (PlainsGold), WestBred, AgriPro, Limagrain, AGSECO, Oklahoma State University (Oklahoma Genetics, Inc) and Polansky Seed. The strengths and weakness of each variety were discussed by Haag, K-State Wheat Pathologist Dr. Kelsey Andersen Onofre, and K-State Multi-County Agronomist Jeanne Falk Jones. If a farmer is looking for a new wheat variety, they should watch SY Wolverine, TAM 115, WB 4792, KS Hamilton and KS Western Star. These are all varieties that have been released in the last couple years and may be a fit for the area. 
Dr. Andersen Onofre lead an extensive discussion on the stripe rust infection this year. The stripe rust pressure appeared in wheat fields later than typically expected and this was likely due to the dry conditions in the area and areas south. However, when the rainy, damp and cool weather arrived, the stripe rust spores were able to infect the wheat leaves. The incubation period for the stripe rust is roughly 10 days and the stripe rust started to appear about that long after the first damp weather. Several fungicides provided good control of stripe rust and availability of fungicides likely determined what farmers applied to wheat for stripe rust control. 
Zukoff also discussed Russian wheat aphids because they are being found in higher frequency this year than the prior several years. Infected wheat tillers may have wheat heads that appear curved like a question mark because the awns may have gotten trapped in a rolled-up flag leaf. Russian wheat aphid feeding can cause the flag leaf to roll up like a straw and can cause yellow, white or purple colored striping on the leaf. The aphids are a light green color and are football shaped. By unrolling the striped leaf, the aphids will be found inside the roll. Insecticides can be applied to control these aphids and the threshold for treating the Russian wheat aphid is 20% or more tillers infected at the flowering stage. When looking for Russian wheat aphids in the wheat plots, Zukoff pointed out several growth stages of lady beetles. Both the larval and adult stages of lady beetles feed on aphids, suppressing the aphid population.
The final stop of the tour was the occasional tillage study. Dr. Schlegel discussed this study that is looking at a single tillage operation with a sweep plow, in a 3-year wheat-sorghum-fallow rotation. This research is in response to farmers asking if a single pass with a tillage implement would decrease the benefits of a no-till system. Many farmers are struggling to control troublesome weeds, like herbicide resistant kochia and Palmer amaranth, and herbicide tolerant weeds, like tumble windmillgrass. This study has been conducted at the Tribune station since 2014. There are three treatments in this study, including a no-till treatment, a tillage pass in fallow in June, and a tillage pass after harvest in July. There was no statistical difference between treatments for wheat yields averaged across years. The average sorghum yield was 121, 118 and 114 bu/acre for no-tillage, June in fallow, and July post-harvest, respectively. These yields were statistically different. There was discussion that timely herbicide applications, specifically preemergence herbicides, in good growing conditions make controlling these challenging weeds a bit easier. Falk Jones noted that many times weed control is happening in much less than ideal conditions. She said that tumble windmillgrass is a shallowly rooted grass, with most of its roots in the top 3-4 inches. Many times, when it is being sprayed it is drought stressed and not actively taking up herbicides. 
Also, at this stop, Dr. Schlegel mentioned the near record rainfall on May 16, with an official 5.66 inches in a 24-hour period on the K-State Tribune Experiment Station. This is the second highest daily precipitation recorded since 1900. The highest amount was recorded on June 4, 1932 with 6.46 inches in the 24-hour period. He then asked the crowd how much of the rain received from May 6 to May 18 was stored in the soil? The total precipitation during that period was 8.27 inches. There were several guesses ranging from 25 to 70% stored. The answer was roughly 50% of the precipitation was stored in the soil. This was determined by water measurements from two long-term studies with neutron access tubes to measure soil water (a very accurate water measurement tool that will measure 8 feet deep). There were some differences in this amount depending on the slope of the ground and the amount of residue on the soil surface.
All in all, the K-State Spring Crop Tour was a success and attendees gained a great deal of knowledge by attending. Results from these studies will be available after harvest. Please call the Experiment Station for more information on specific studies.

 

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