Kansas Winter Wheat Research Articles

Mid-season nitrogen management for winter wheat under price and weather uncertainty

ContextIn-season nitrogen (N) management tools are essential for optimizing N application rates, maximizing farmers’ economic returns and minimizing adverse environmental impacts. The primary limitation to developing such tools is the risk associated with uncertainties in weather forecasts and crop price projections required to estimate yields and returns for different N rates. Therefore, characterizing the risk associated with these uncertainties is crucial for determining optimum N rates in-season. ObjectiveThis study investigated the N application decision-making process for farmers, accounting for risks associated with weather and crop price uncertainties through crop modeling and economic analysis. MethodsWe used field trial data for winter wheat in Kansas to examine how optimal nitrogen rates and economic returns vary over sites, years, and differing farmers’ risk attitudes. First, the Environmental Policy Integrated Climate (EPIC) agroecosystem model was used to simulate the distribution of final yields under different N applications during early spring. Then, an autoregressive moving average (ARMA) model estimated the wheat price distribution at harvest based on historical prices. Finally, optimal N application rates for farmers with different risk appetites were estimated using two risk decision models: the constant-absolute-risk-averse (CARA) expected utility model, which treats upside (higher-than-expected returns) and downside (lower-than-expected returns) deviations equally, and the invariant-preference, generalized-deviation (IPGD) model, which focuses on downside risk. ResultsWe found that optimal N rates vary greatly between sites and years, as well as across farmers with different risk preferences. Due to the positive skewness of economic return distribution, farmers tend to apply lower N rates when considering downside risk. On average, the optimal N rate for farmers with a CARA coefficient of 0.002 is 77 kg/ha in the CARA model and 67 kg/ha in the IPGD model. Compared to the outcome of risk-neutral N usage, risk-averse N usage for a farmer with a CARA coefficient of 0.008 could reduce the uncertainty (standard deviation) of return by 6.2 %, on average, while the expected return decreased by only 1.2 %. ConclusionsBy lowering the N rate, risk-averse farmers would reduce the uncertainty of returns and incur a minor return loss, suggesting the possibility of improving agricultural resilience while also improving N use efficiency. Our analysis also underscores the importance of yearly site-specific N management, given the substantial variation in optimal rates across years and locations. SignificanceThis study provides the foundation for an N application decision framework that considers both weather and price uncertainty. The analysis also demonstrates the potential co-benefit of enhancing agriculture’s climate and market resilience while potentially lowering N losses.

Chloride Fertilization’s Impacts on Kansas Winter Wheat Grain Yield During 2021-2022

Chloride Fertilization’s Impacts on Kansas Winter Wheat Grain Yield During 2021-2022

Optimized Yellow Dwarf Virus Multiplex PCR Assay Reveals a Common Occurrence of Barley yellow dwarf virus-PAS in Kansas Winter Wheat

Barley yellow dwarf is an aphid-transmitted virus disease caused by yellow dwarf virus (YDV) species in the family Luteoviridae. Previous partial sequencing efforts conducted in Kansas revealed that Barley yellow dwarf virus-PAS (PAS) occurs in winter wheat fields, and currently available YDV multiplex reverse-transcription PCR (RT-PCR) assays do not detect this species. To enable precise determination of YDV species for research, disease diagnostic, and plant breeding programs, this study enhanced and validated the utility of a multiplex RT-PCR protocol to discriminate six YDV species, including PAS, in archived and fresh field samples. From a representative subset of samples collected from commercial and variety trial locations across nine wheat growing regions of Kansas, PAS and Barley yellow dwarf virus-PAV (PAV) were equally prevalent in single or mixed infections, and other YDVs occurred in mixed infections with PAS and/or PAV in low numbers. The optimized multiplex assay provided robust and specific detection of YDVs and showed promise as a diagnostic tool for determining species occurrence and composition of YDVs in an intensive wheat cropping region of the United States.

Crop Water Production Functions of Grain Sorghum and Winter Wheat in Kansas and Texas

AbstractProductivity of water‐limited cropping systems can be reduced by untimely distribution of water as well as cold and heat stress. The objective of this study was to evaluate the predictive accuracy of the Kansas Water Budget (KSWB) model for crop water use and grain productivity of grain sorghum and winter wheat grown in a range of crop sequences. The relationship of grain yield to crop water use, reported in several crop sequence studies conducted in Bushland, TX, and Colby and Tribune, KS, was compared against the KSWB modeling results. Field studies showed that the yield responses of grain sorghum to an increment of water use was generally 75% greater than that of winter wheat, as expected for crops with C4 and C3 physiology, respectively. The relationship of winter wheat yield to crop water use, simulated by the KSWB model, was comparable to relationships developed in four of five studies, with the exception of one study conducted in Bushland that suggested less crop water productivity. For grain sorghum, experimental yield response to an increment of water use was less than that calculated for three of five cases; for one study at Colby and Tribune, simulated and experimental yield response to water use were similar. Simulated yield thresholds were consistent with observed yield thresholds for both wheat and sorghum in all but one case. The KSWB model provides a useful analytic framework for distinguishing water supply constraints to grain productivity.

Environmental Conditions Associated with Stripe Rust in Kansas Winter Wheat.

Stripe rust has reemerged as a problematic disease in Kansas wheat. However, there are no stripe rust forecasting models specific to Kansas wheat production. Our objective was to identify environmental variables associated with stripe rust epidemics in Kansas winter wheat as an initial step in the longer-term goal of developing predictive models for stripe rust to be used within the state. Mean yield loss due to stripe rust on susceptible varieties was estimated from 1999 to 2012 for each of the nine Kansas crop reporting districts (CRD). A CRD was classified as having experienced a stripe rust epidemic when yield loss due to the disease equaled or exceeded 1%, and a nonepidemic otherwise. Epidemics were further classified as having been moderate or severe if yield loss was 1 to 14% or greater than 14%, respectively. The binary epidemic categorizations were linked to a matrix of 847 variables representing monthly meteorological and soil moisture conditions. Classification trees were used to select variables associated with stripe rust epidemic occurrence and severity (conditional on an epidemic having occurred). Selected variables were evaluated as predictors of stripe rust epidemics within a general estimation equations framework. The occurrence of epidemics within CRD was linked to soil moisture during the fall and winter months. In the spring, severe epidemics were linked to optimal (7 to 12°C) temperatures. Simple environmentally based stripe rust models at the CRD level may be combined with field-level disease observations and an understanding of varietal reaction to stripe rust as part of an operational disease forecasting system in Kansas.

Occurrence of Viruses and Associated Grain Yields of Paired Symptomatic and Nonsymptomatic Tillers in Kansas Winter Wheat Fields.

Vector-borne virus diseases of wheat are recurrent in nature and pose significant threats to crop production worldwide. In the spring of 2011 and 2012, a state-wide sampling survey of multiple commercial field sites and university-managed Kansas Agricultural Experiment Station variety performance trial locations spanning all nine crop-reporting regions of the state was conducted to determine the occurrence of Barley yellow dwarf virus-PAV (BYDV-PAV), Cereal yellow dwarf virus-RPV, Wheat streak mosaic virus (WSMV), High plains virus, Soilborne wheat mosaic virus, and Wheat spindle streak mosaic virus using enzyme-linked immunosorbent assays (ELISA). As a means of directly coupling tiller infection status with tiller grain yield, multiple pairs of symptomatic and nonsymptomatic plants were selected and individual tillers were tagged for virus species and grain yield determination at the variety performance trial locations. BYDV-PAV and WSMV were the two most prevalent species across the state, often co-occurring within location. Of those BYDV-PAV- or WSMV-positive tillers, 22% and 19%, respectively, were nonsymptomatic, a finding that underscores the importance of sampling criteria to more accurately assess virus occurrence in winter wheat fields. Symptomatic tillers that tested positive for BYDV-PAV produced significantly lower grain yields compared with ELISA-negative tillers in both seasons, as did WSMV-positive tillers in 2012. Nonsymptomatic tillers that tested positive for either of the two viruses in 2011 produced significantly lower grain yields than tillers from nonsymptomatic, ELISA-negative plants, an indication that these tillers were physiologically compromised in the absence of virus-associated symptoms. Overall, the virus survey and tagged paired-tiller sampling strategy revealed effects of virus infection on grain yield of individual tillers of plants grown under field conditions and may provide a complementary approach toward future estimates of the impact of virus incidence on crop health in Kansas.

Management Strategies for Barley Yellow Dwarf on Winter Wheat in Kansas

Barley yellow dwarf (BYD) is one of the most important wheat diseases in the state of Kansas. Several methods of disease management have been recommended to mitigate losses from BYD including the use of seed-treatment insecticides, delayed planting of winter wheat, and deploying cultivars with resistance to BYD. The goal of this research was to quantify the impact of these three management strategies, alone and in combination, on BYD disease progress and grain yields in Kansas. When field experiments were averaged over four years, treating seed with the insecticide imidacloprid (Gaucho) reduced the daily increase in the area under the disease progress curve (AUDPC) by 35.0% and corresponding yield losses from BYD by 16.4%. Compared with early planting, late planting reduced AUDPC by 47.9% and corresponding yield losses by 57.5%. Planting a moderately resistant cultivar reduced AUDPC by 80.9% and corresponding yield losses by 72.6% compared with a susceptible cultivar. When all three BYD management methods were combined, BYD was reduced by 95.2% and yield losses reduced by 97.1% when compared with not using any of the management methods. Therefore, integrating management practices can result in high levels of control of BYD in Kansas. Accepted for publication 4 May 2016. Published 7 June 2016.

Estimating Yield Gaps With Limited Data: An Application to United States Wheat

The objective of this research is to estimate and analyze the gap between in‐trial yield potential, on‐farm yield potential, and actual on‐farm wheat yields. Yield gaps are quantified by measuring how varietal mean yields have changed over time, due to productivity increases generated by public and private wheat breeding programs. Variety performance trial data for Kansas winter wheat are used to summarize the evolution of wheat yields over the time period 1985 to 2011. A measure of yield potential is compared to actual on‐farm yields to derive implications for wheat industry stakeholders. Persistent and expanding yield gaps between potential yield and actual on‐farm yield are measured and analyzed. Producers’ variety adoption decisions explain a relatively small portion of this gap, and producers have become more effective at identifying and adopting yield‐enhancing varieties over time. The largest portion of these gaps was explained by on‐farm production decisions.

Estimating Yield Losses Due to Barley Yellow Dwarf on Winter Wheat in Kansas Using Disease Phenotypic Data

Barley yellow dwarf (BYD) is one of the most important wheat diseases in the state of Kansas. Despite the development of cultivars with improved resistance to BYD, little is known about the impact that this resistance has on yield loss from the disease. The intent of this research was to estimate yield loss in winter wheat cultivars in Kansas due to BYD and quantify the reduction in losses associated with resistant cultivars. During seven years, BYD incidence was visually assessed on numerous winter wheat cultivars in replicated field nurseries. When grain yields were regressed against BYD incidence scores, negative linear relationships significantly fit the data for each year and for the combined dataset covering all seven years. The models showed that, depending upon the year, 19–48% (average 33%) of the relative yields was explained by BYD incidence. For the combined dataset, 29% of the relative yield was explained by BYD incidence. The models indicated that cultivars showing the highest disease incidence that year had 25–86% (average 49%) lower yield than a hypothetical cultivar that showed zero incidence. Using the models, the moderate level of resistance in the cultivar Everest was calculated to reduce yield loss from BYD by about 73%. Therefore, utilizing visual BYD symptom evaluations in Kansas coupled with grain yields is useful to estimate yield loss from the disease. Accepted for publication 1 December 2014. Published 9 January 2015.

Registration of a Hard Red Winter Wheat Genetic Stock Homozygous for ph1b for Facilitating Alien Introgression for Crop Improvement

Wild relatives of common wheat (Triticum aestivum L.) are important sources of disease and pest resistance that can be exploited in wheat improvement. However, in wheat–alien species hybrids the pairing homeologous gene, Ph1, suppresses the pairing and recombination of wheat and alien chromosomes and no alien genetic transfer can occur. However, in plants nullisomic for the Ph1 gene, and in ph1b mutant stocks, having a large deletion at the Ph1 locus, homeologous wheat and alien chromosomes can pair and recombine. The original ph1b mutant stock is in Chinese Spring background, which has poor agronomic characteristics, and several backcrosses with adapted wheat cultivars are necessary before the agronomic performance of recombinants can be evaluated. The present report describes the transfer and characterization of the ph1b mutant allele into an adapted Kansas winter wheat, which was released as KS12WGGRC55 (TA5092) (Reg. No. GS‐170, PI 663870), which will accelerate the evaluation and utilization of wheat alien recombinants in cultivar improvement.

Inheritance of Resistance to Stagonospora nodorum Leaf Blotch in Kansas Winter Wheat Cultivars.

Stagonospora nodorum blotch can cause serious yield and quality losses of wheat (Triticum aestivum) in many countries worldwide. Although there are other control methods, host resistance is the most desirable. Three recent Kansas winter wheat cultivars (Betty, Heyne, and 2163) have been developed with moderate levels of resistance to the leaf phase of Stagonospora nodorum blotch. To determine inheritance of resistance and allelism, these cultivars were crossed with one of three susceptible lines (Larned, KS96WGRC39, or Newton) and intercrossed in all possible combinations, including reciprocals. The parents, F1, F2, and F3 generations were tested for resistance to S. nodorum in the greenhouse as 4-week-old seedlings. Cytoplasmic effects were not detected in any cross. The mean levels of infection in the F1s of the two crosses Betty × Larned and Heyne × KS96WGRC39 indicated resistance was dominant. The observed phenotypic ratios of F2 plants for both crosses were not significantly different from the expected ratio for a single dominant gene. The ratio observed for F3 lines in the Betty × Larned cross fit that expected for a single dominant gene. However, the observed ratio of the F3 lines from the cross Heyne × KS96WGRC39 did not fit the ratio expected for a single dominant gene. The allelism test for Betty and Heyne indicated that they have different resistance genes. The F1 mean rating of the cross 2163 × Newton was intermediate between the two parents, indicating the absence of dominance for resistance in 2163. The phenotypic ratio observed in the F2 plants from this cross did not fit the ratio expected for a single dominant gene. The simple genetic control of resistance in cv. Betty makes it a useful source of resistance for wheat breeding programs.

Yield and Nitrogen Uptake of Spring Wheat Planted in a Ridge-Till System

Conservation tillage and inclusion of a cover crop that provides surface residue cover are two management options for reducing soil erosion losses commonly found in a corn (Zea mays L.)-soybean [Glycine max (L.) Merr] rotation. Information is lacking, however, on the performance of a small grain planted in a ridge-tillage system in the Northern Corn Belt. A 3-yr (1992-1994) study was conducted to determine the effect of row position (ridge, shoulder, furrow, and wheel track furrows) on yield and N uptake of hard red spring wheat (Triticum aestivum L.) planted in a ridge-tillage system on poorly drained Webster clay loam (fine-loamy, mixed, mesic Typic Haplaquoll) soil at two locations in southern Minnesota. Spring wheat was planted after soybean in 15 ft wide strips. Wheat performance was affected by the position of the row across the ridged seedbed. Averaged across the 3 yr, grain yield of the wheat rows planted on ridge top and shoulder positions was 31% greater than those rows planted in the furrows at both locations. Grain yield of wheat in the wheel track furrows was reduced by 38% at Freeborn and by 33% at Waseca compared with those planted on ridge tops and shoulders when averaged across years. Moreover, grain yield in the wheel track furrows was reduced by 18% at Freeborn and by 12% at Waseca compared with non-wheel track furrows across years. Similar to grain yield, straw yield and total N uptake were greater in the ridge top and shoulder positions than in either non-wheel track or wheel track furrow positions. Lesser grain yield in the furrows and wheel track furrows correlated well with reduced head numbers in these row positions compared with ridge top and shoulder positions. The results from this study indicate that wheat can be successfully planted in a ridge-tillage system. Yield losses, however, occur in the furrows and controlled wheel track furrows, especially in wet years in this ridge-till system.

Utilizing Grain Yield Data from Wheat Demonstration Plots

Utilizing Grain Yield Data from Wheat Demonstration Plots

Experimental Evaluation of Predators and Parasitoids in Suppressing Greenbugs (Homoptera: Aphididae) in Sorghum and Wheat

The effectiveness of endemic predators and parasitoids as biological control agents of the greenbug, Schizaphis graminum (Rondani), was experimentally evaluated during 1985 and 1986 in Kansas winter wheat, Triticum aestivum , and grain sorghum, Sorghum bicolor. Mechanical exclusion was used as the experimental method of evaluation. The coccinellids Coleomegilla maculata lengi Timberlake, Hippodamia convergens Guerin, and Scymnus spp. were the predominant predators of greenbugs in sorghum and comprised 89% of the predator population. Lysiphlebus testaceipes (Cresson) was the most abundant primary parasitoid in sorghum. The natural enemy complex was able to suppress experimental greenbug densities at all stages of sorghum growth from 3-leaf through the boot stage. The impact of L., testaceipes on greenbugs was sporadic between locations. In winter wheat, H. convergens was the most abundant natural enemy and significantly suppressed greenbug densities. Natural enemies, primarily coccinellids, consistently reduced experimental greenbug populations in winter wheat and grain sorghum.

Identification of Wheat Spindle Streak Mosaic Virus and Its Role in a New Disease of Winter Wheat in Kansas

Identification of Wheat Spindle Streak Mosaic Virus and Its Role in a New Disease of Winter Wheat in Kansas

The role of vesicular–arbuscular mycorrhizal fungi in the growth of Kansas winter wheat

In field experiments, fall-planted hard red winter wheat plants failed to become mycorrhizal until May or June just prior to harvest. No benefit to yield was evident from this late-season colonization, and in-furrow infestation with Glomus mosseae or Glomus epigaeum failed to provide earlier colonization or any increased yield. Neither were these mycorrhizal fungi successful in reducing the soil-borne diseases Cephalosporium stripe and take-all in the field. All eight wheat cultivars tested became mycorrhizal under greenhouse conditions whether nonsterile field soil was amended or not with a vesicular–arbuscular (VAM) fungus. Volunteer wheat plants collected from the field during summer also showed some limited level of colonization. Plants grown at 10 °C failed to be colonized, but plants grown at 25 °C were mycorrhizal after 10 weeks. Therefore, the observed failure of winter wheat in the field to become mycorrhizal until late in the growing season could not be explained by cultivar resistance or insufficient inoculum levels in field soils but may be attributed to low fall soil temperatures which may inhibit spore germination or root colonization. Thus, under field conditions it appears that mycorrhizal fungi have little or no effect on winter wheat in Kansas, but the isolation of cold-tolerant, highly efficient isolates should be pursued.

Further Studies on Pale Western Cutworm Control in Kansas, 1968–6912

Three field tests were conducted on winter wheat in Kansas during 1968 and 1969 using 11 insecticides against Agrotis orthogonia Morrison. All, except disulfoton at 0.75 lb Al/acre and Bux® Insecticide ( m -(1-ethylpropyl) phenyl methylcarbamate mixture (1–4) with m -(1-methylbutyl) phenyl methylcarbamate) at 1 lb Al/acre, significantly reduced larval populations below the untreated check. However, only CL-47031 (cyclic ethylene (diethoxyphosphinyl) dithioimidocarbonate) at 0.75 and 0.375 lb Al/acre and monocrotophos at 0.3 and 0.6 lb Al/acre were superior to the endrin standard. None of the treatments increased seed yields in irrigated wheat. In dryland wheat, however, monocrotophos, endosulfan, and Lannate® ( S -methyl N -[(methylcarbamoyl) oxy]thioacetimidate) significantly increased seed yields.

Further Evaluation of Acaricides for Brown Wheat Mite Control on Winter Wheat in Kansas, 1963–651

Sixteen acaricidal sprays were evaluated against Petrobia latens (Műer) in field experiments in western Kansas from 1963 through 1965. Single applications of dimethoate, parathion, demeton, Dasanit® (O, O -diethyl O -[ p- (methylsulfinyl) phenyl] phosphorothioate), carbophenothion, ethion, Tranid® (exo -5-chloro-6-oxo- endo -2-norbornanecarbonitrile O- (methylcarbamoyl) oxime), UC 19786 (2- sec -butyl-4,6-dinitrophenyl isopropyl carbonate), Niagara 10242 (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate), and diazinon reduced populations 77% or more approximately one week after being applied. With dimetilan, Isolan® (l-isopropyl-3-methyl-5-pyrazolyl (dimethylcarbamate), Morestan® (6-methyl-2,3-quinoxalinedithiol cyclic S, S -dithio carbonate), GC 9879 (4-hydroxy-2-mercaptobutyric acid, gamma -lactone, S -ester with O,O -diethyl phosphorodithioate), tetradifon, and binapacryl mite populations were reduced 68% or less. In general, most treated plots yielded more seed wheat than untreated plots; however, increases were statistically significant in only I experiment.

Soil Moisture and Winter Wheat in Kansas

Soil Moisture and Winter Wheat in Kansas