Winter Wheat Variety Response to Flag Leaf Foliar Fungicide Application in 2019–2020

Foliar fungicide can be an important tool in improving wheat yields, but its effectiveness is season- and variety-dependent. To evaluate the yield, test weight, and protein responses of different commercial winter wheat varieties to one foliar fungicide application around heading, we conducted a trial combining four winter wheat varieties and two fungicide management treatments in Manhattan during 2019–2020. The control treatment consisted of no fungicide application, and the alternative treatment consisted of 5 oz/a Absolute Maxx + NIS applied at heading. Varieties evaluated were Bob Dole, Larry, WB4269, and Zenda. The study was conducted under no-tillage practices following a previous soybean crop. Grain yield across varieties averaged 47.8 bushels per acre in the control and 51.3 bu/a in the fungicide treatment. Zenda was the highest yielding variety (51.3 bu/a), followed by Larry (48.9 bu/a), and WB4269 and Bob Dole (~45.5 bu/a). The statistical analysis suggested that all varieties responded similarly to the fungicide application, but we hypothesize that this was because we did not have enough observations to build statistical power. Grain test weight and protein concentration were only impacted by variety and showed no fungicide effect (both were usually greater in Bob Dole and Larry as compared to Zenda or WB4269). These results suggest that the yield increase due to fungicide application did not result in protein dilution, likely due to an extended period for nitrogen (N) uptake and remobilization into the grain. Further research is needed to statistically detect significant differences among varieties in their response to foliar fungicide

Winter Wheat Response to Different Fungicide Management (Products and Timing of Application) During the 2019-2020 Growing Season

Foliar fungicides can improve wheat grain yield in Kansas, but there is limited information on the efficacy of different products as well as the timing of application. We conducted a field study in five Kansas locations to evaluate the yield, test weight, and protein responses of WB-Grainfield to different commercial fungicides applied at different times during the growing season. The trial was conducted in a randomized complete block design to evaluate (1) a non-treated control; Topguard applied at 5 ounces per acre at (2) jointing, (3) heading, and (4) jointing plus heading; (5) Delaro applied at 6 oz/a at jointing; (6) Absolute Maxx applied at 5 ounces per acre at heading; (7) Delaro at jointing plus Absolute Maxx at heading at the rates previously specified; and (8) Nexicor applied at 13 oz/a at heading. The study was conducted near Conway Springs, Great Bend, two sites near Hutchinson (optimum- and late-sowing date), and Leoti. Grain yield across locations ranged from 36 to 72.9 bushels per acre. A significant fungicide by location interaction on grain yield resulted from two locations showing no response to fungicide; two locations resulting in the highest yield when fungicide at heading was presented in the evaluated treatment; and one location showing all fungicide treatments outyielding the control. Similar results were obtained for test weight, where fungicides at heading seemed to benefit test weight at all locations except at the driest one. There were no consistent effects of foliar fungicide management on wheat grain protein concentration. This research is an initial step in determining the benefits of foliar fungicide to winter wheat yield and to date, a preliminary conclusion highlights the usefulness of a heading fungicide application when precipitation is not a limiting factor to yields, without consistent differences among the evaluated products

Winter Wheat Variety Response to Timing and Number of Fungicide Applications During the 2019–2020 Growing Season in Kansas

The objective of this project was to evaluate the yield response of different winter wheat varieties to different fungicide management treatments during the 2019–2020 growing season in Kansas. Fourteen varieties were evaluated under four fungicide treatments (no fungicide, application either at jointing, heading, or at both stages) in five locations across Kansas in a split-plot design. Disease incidence was assessed approximately 20-d after each fungicide application. Septoria blotch and tan spot were the most prevalent early-season diseases at the studied fields, while stripe rust, leaf rust, and tan spot prevailed late in the season. Late-season diseases had a greater effect on grain yield when compared to early-season diseases. While varieties responded differently to fungicide management, there was an overall yield increase of 1.8 bushels per acre resulting from the jointing fungicide application; 3.3 bu/a from the heading fungicide; and 4.3 bu/a from the combination of both applications. Overall, susceptible varieties had a greater response to fungicide management compared to varieties with intermediate or high levels of genetic resistance. Late-season drought and heat stress affected three out of five locations (Belleville, Conway Springs, and Hutchinson planted late), resulting in less effect of fungicide management than in the other two locations (Ashland Bottoms and Hutchinson planted in the optimal timing). Although there were some similarities, the ranking of the highest yielding varieties was not uniform across locations. Our preliminary data suggest that the application of fungicide to winter wheat in Kansas might be advantageous, but the degree of this benefit will depend upon the environment and on the variety

Does Winter Wheat Yield Response to Fungicide Application Depend on Nitrogen Management?

Nitrogen and fungicide are among the more important management tools to increase wheat (Triticum aestivum L.) grain yield in Kansas. However, there is limited information on whether hard red winter wheat grain yield is impacted by the interaction of nitrogen rates and foliar fungicide application. Thus, our objective was to evaluate the effects of different N rates with or without a fungicide application at Feekes 10.5 on grain yield of two winter wheat genotypes with contrasting disease resistances to leaf and stripe rust. Eleven field experiments were established across Kansas using a factorial structure of two fungicide management options (either no fungicide or 13 fl oz of Nexicor per acre), five N rates (0, 30, 60, 90, and 120 pounds of N per acre), and two genotypes (Larry and Zenda) in a split-split plot design during the 2021–2022 growing season. There was a significant interaction between genotype and environment where Larry out-yielded Zenda in anywhere from 3.1 to 15 bu/a. There was a significant interaction between N rate and environment, likely due to the initial soil NO3-N and yield potential, as grain yield ranged from less than 34 to more than 81 bu/a. Increases in fractions of canopy cover in response to N fertilization and fungicide application explained about 29% and 15% of the increases in grain yield, respectively. There was a slightly greater crop yield response to foliar fungicide application as the N supply increased, from a nearly null difference at low N supply to as much as 5.9% for total N supply greater than 160.7 lb of N/a. In dry conditions with minimal disease incidence, winter wheat response to N availability differed in each environment, but there was only a marginal response to foliar fungicide

Winter Wheat Response to Timing of Fungicide Application During the 2020–2021 Growing Season

Foliar fungicides applied at the flag leaf stage can improve wheat grain yield in Kansas, but there is limited information on the impact of earlier or combined applications of fungicide on wheat grain yield. We conducted a field study in six Kansas locations during the 2020–2021 growing season to evaluate the yield and test weight of the winter wheat variety WB-Grainfield in response to different fungicide application timings. The trial was conducted in a randomized complete block design with four replications to evaluate (1) a non-treated control; Topguard applied at 5 ounces per acre at (2) jointing, (3) heading; and (4) jointing plus heading. The study was conducted in two locations with contrasting soil textures near Ashland Bottoms, in two locations with different previous crops resulting in optimum- and late-sowing dates near Belleville, in one location near Hutchinson, and another near Manhattan. Statistical analysis indicated that for both grain yield and grain test weight, there were significant fungicide timing by location interactions, suggesting that the response to fungicide was location-specific. Grain yield ranged from 28 bushels per acre in the no fungicide treatment in Manhattan to 109.9 bu/a with dual-fungicide in the Belleville field sown at the optimum time. Depending on environment, the increase in yield due to the fungicide application as compared to the untreated control ranged from 0.7 to 8.0 bu/a in the jointing application, from -1.8 to 19.3 bu/a in the heading application, and from -1.4 to 17.7 bu/a in the dual application. Grain test weights ranged from 54.1 pounds per bushel without fungicide in one of the trials near Ashland Bottoms, to 62.8 lb/bu near Hutchinson with the dual fungicide application. Test weight benefits due to fungicide depended on location and ranged from -0.1 to 1.7 lb/bu in the jointing application, from -0.9 to 2.6 lb/bu in the heading application, and from -0.3 to 3.9 lb/bu in the dual application. This research is an initial step in determining the benefits of foliar fungicide timing to winter wheat yield and test weight. The results from this study suggest that benefits are substantial, however, the magnitude depended on the environmental conditions experienced during the growing season

Winter Wheat Variety Response to Timing and Number of Fungicide Applications During the 2020–2021 Growing Season in Kansas

The objective of this project was to evaluate the yield response of different winter wheat varieties to different fungicide management treatments during the 2020–2021 growing season in Kansas. Fourteen varieties were evaluated under four fungicide treatments (no fungicide, application either at jointing, heading, or at both stages) in four locations across Kansas in a split-plot design. Disease incidence was assessed approximately 20 d after each fungicide application. Septoria blotch and tan spot were the most prevalent early-season diseases at the studied fields, while stripe rust, leaf rust, and tan spot prevailed later in the season. While varieties responded differently to fungicide management and there was a range in yield response across locations, there was an overall yield increase of 4.2 bushels per acre resulting from the jointing fungicide application; 10.3 bu/a from the heading fungicide; and 9.9 bu/a from the combination of both applications. Although there were some similarities, the ranking of the highest yielding varieties was not uniform across locations. While different reactions occurred regarding the response of the varieties to fungicide management, overall susceptible varieties had a greater response to fungicide management compared to varieties with intermediate or high levels of genetic resistance. Our preliminary data suggest that the application of fungicide to winter wheat in Kansas might be advantageous, but the degree of this benefit will depend upon the environment, variety, and level of disease incidence

Temporal Dynamics of Wheat Blast Epidemics and Disease Measurements Using Multispectral Imagery

Wheat blast is a devastating disease caused by the Triticum pathotype of Magnaporthe oryzae (MoT). MoT is capable of infecting leaves and spikes of wheat. Although symptoms of spike blast (WSB) are quite distinct in the field, symptoms on leaves (WLB) are rarely reported since they are usually less noticeable. Two field experiments were conducted in Bolivia to characterize the change in WLB and WSB intensity over time and determine if multispectral imagery can be used to accurately assess WSB. Disease progress curves (DPCs) were plotted from WLB and WSB data, and regression models were fitted to describe the nature of WsB epidemics. Although WLB severity was low during the vegetative stages, there was a bimodal shape when WLB incidence DPCs were plotted. The Gompertz model best described WSB intensity change over time in both inoculated and non-inoculated plots from both locations (R2=0.94-0.98; RMSE=0.16-0.58). Lin’s concordance correlation coefficients were estimated to measure agreement between visual estimates and digital measurements of WSB intensity and to estimate accuracy, and reliability. Our findings suggest that the change of wheat blast intensity in a susceptible host population over time does not follow a pattern of a monocyclic epidemic. We have also demonstrated that WSB severity can be quantified using non-green vegetation pixels reliably (0.91-0.960.68-0.83) and accurately (0.86-0.920.56-0.71) at moderately-low-to-high visual WSB severity levels. Additional sensor-based methods must be explored to determine their potential for detection of WLB and WSB at earlier stages

The effect of follicle age on pregnancy rate in beef cows

The effect of the age of the ovulatory follicle on fertility in beef cows was investigated. Multiparous (n = 171) and primiparous (n = 129) postpartum beef cows in 2 groups (G1 and G2) received estradiol benzoate (EB; 1 mg/500 kg BW, intramuscular [i.m.]) 5.5 d (G1; n = 162) and 6.5 d (G2; n = 138) after the final GnRH of a synchronization program (5d CO-Synch + CIDR) to induce emergence of a new follicular wave (NFW), followed by prostaglandin F2 alpha (PGF2 alpha; 25 mg, i.m.) administration either 5.5 d (young follicle, YF; n = 155) or 9.5 d (mature follicle, MF; n = 145) after EB. Estrous detection coupled with AI 12 h later (estrus-AI) was performed for 60 h (MF) and 84 h (YF) after PGF(2 alpha); cows not detected in estrus within this period received timed AI (TAI) coupled with GnRH at 72 and 96 h, respectively. Within the first 72 h after PGF(2 alpha), more (P < 0.01) cows in the MF (76.3%) than YF treatment (47.7%) exhibited estrus, but through 96 h, the proportion detected in estrus (P < 0.05) and interval from PGF(2 alpha) to estrus (P < 0.01) were greater in the YF than MF treatment (88.6% vs. 76.3%, 78.9 +/- 0.8 vs. 57.5 +/- 1.6 h, respectively). Age of the ovulatory follicle at AI was greater (P < 0.01) in the MF (9.32 +/- 0.04 d) than YF (6.26 +/- 0.02 d) treatment, but follicle diameter at AI and pregnancy rates did not differ between MF (13.1 +/- 0.2 mm; 72.0%) and YF (12.9 +/- 0.1 mm; 67.1%) treatments. Regardless of treatment, the diameter of the ovulatory follicle at AI and pregnancy rate were greater (P < 0.01) with estrus-AI (13.1 +/- 0.1 mm; 75.0%) than TAI (12.6 +/- 0.2 mm; 55.4%). Cows in the MF treatment that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 47) were induced to ovulate with GnRH and TAI at 72h, when ovulatory follicles were 4 d old and 10.2 +/- 0.2 mm in diameter. Pregnancy rate for TAI (51.1%) in MF2 did not differ from TAI pregnancy rate (55.4%) across the MF and YF treatments. In summary, the age of the ovulatory follicle affected interval to estrus and AI but did not influence pregnancy rate in suckled beef cows

Temporal Dynamics of Wheat Blast Epidemics and Disease Measurements Using Multispectral Imagery.

Wheat blast is a devastating disease caused by the Triticum pathotype of Magnaporthe oryzae. M. oryzae Triticum is capable of infecting leaves and spikes of wheat. Although symptoms of wheat spike blast (WSB) are quite distinct in the field, symptoms on leaves (WLB) are rarely reported because they are usually inconspicuos. Two field experiments were conducted in Bolivia to characterize the change in WLB and WSB intensity over time and determine whether multispectral imagery can be used to accurately assess WSB. Disease progress curves (DPCs) were plotted from WLB and WSB data, and regression models were fitted to describe the nature of WSB epidemics. WLB incidence and severity changed over time; however, the mean WLB severity was inconspicuous before wheat began spike emergence. Overall, both Gompertz and logistic models helped to describe WSB intensity DPCs fitting classic sigmoidal shape curves. Lin's concordance correlation coefficients were estimated to measure agreement between visual estimates and digital measurements of WSB intensity and to estimate accuracy and precision. Our findings suggest that the change of wheat blast intensity in a susceptible host population over time does not follow a pattern of a monocyclic epidemic. We have also demonstrated that WSB severity can be quantified using a digital approach based on nongreen pixels. Quantification was precise (0.96 0.83) and accurate (0.92 0.69) at moderately low to high visual WSB severity levels. Additional sensor-based methods must be explored to determine their potential for detection of WLB and WSB at earlier stages