This is not a comprehensive list of all research conducted at this time.
Synthetic auxin herbicides do not injure intermediate wheatgrass or affect grain yield.
Intermediate wheatgrass (IWG) is a cool-season perennial grass developed as a dual-purpose grain and forage crop. One barrier to adopting this crop is a lack of information on the effects of herbicides on IWG for grain production. An experiment was conducted to evaluate herbicide effects on IWG grain yield, crop injury, and weed control over 2 yr (2019 to 2021) at sites in Wisconsin, Minnesota, New York, and North Dakota. This evaluation included broadleaf herbicides registered for use on wheat: 2,4-D amine, clopyralid, MCPA, and a mixture of clopyralid + MCPA (all are categorized as Group 4 herbicides by the Weed Science Society of America). Each herbicide or mixture was applied at 1× and 2× the labeled wheat application rate to newly planted and established (1- to 5-yr-old) IWG stands in the fall or spring. Herbicides were applied during IWG tillering or jointing stages in the fall or during the jointing stage in the spring. Across site years, application timing, herbicide, and application rate showed no effect on IWG grain yield or plant injury. Broadleaf weed control ranged from 71% to 92% across herbicide treatments relative to the nontreated check at the Wisconsin site, whereas weed control at the Minnesota site was variable among treatments. At the New York site, herbicides were equally effective for broadleaf weed suppression, whereas weed pressure was very low at the North Dakota site and treatments did not affect weed cover. The results show that newly planted and established stands of IWG are tolerant to the synthetic auxin herbicides 2,4-D amine, clopyralid, and MCPA when applied during tillering or jointing in the fall or during jointing in the spring. Synthetic auxins represent a potentially useful tool for weed control in IWG cropping systems, especially for problematic broadleaf weed species.
Shoenberger, E. D., Jungers, J. M., Law, E. P., Keene, C. L., DiTommaso, A., Sheaffer, C. C., Wyse, D. L., Picasso, V. D., & Stoltenberg, D. E. (2023). Synthetic auxin herbicides do not injure intermediate wheatgrass or affect grain yield. Weed Technology, 37(5), 560-568. https://doi.org/10.1017/wet.2023.71
Residual herbicides in corn and their effect on fall-planted cover crop species.
The use of residual herbicides as a part of preemergence (PRE) and in-season layered treatments has proven to be an effective strategy for controlling late-emerging broadleaf weed species in annual crops. However, the use of residual PRE herbicides has the potential to negatively affect other crops within an annual two-crop rotation, such as fall-planted cover crops. The intent of this study was to determine if PRE herbicides commonly used in the upper Midwest United States would affect stand density, height, and biomass production of fall-planted cover crops. Field studies were conducted at three locations that differed in soil type and climate. Four PRE herbicides were applied in silage corn (Zea mays L.) in the spring: dimethenamid-P (single application), dimethenamid-P + saflufenacil, acetochlor + clopyralid + mesotrione, and a layered treatment of dimethenamid-P at planting and 30 days after first application. Three cover crops were planted in the fall following silage corn harvest with a no-till drill: winter cereal rye (Secale cereale L.), winter camelina (Camelina sativa L.), and red clover (Trifolium pratense L.). Although some of the PRE HBs tested affected cover crop spring plant density and height in sandy soils, there was no difference in cover crop biomass production at termination between herbicide treatments, regardless of soil type. These results indicate that the application of these residual PRE herbicides for control of late-emerging weed species did not interfere with cover crop biomass production as long as soil moisture was not limiting.
Ley, E., Johnson, G., Wells, S., Becker, R., Stahl, L., Miller, R., & Sarangi, D. (2023). Residual herbicides in corn and their effect on fall-planted cover crop species. Agrosystems, Geosciences & Environment, 6(4)https://doi.org/10.1002/agg2.20446
Maize performance in a kura clover living mulch under drought conditions.
Row establishment is important to mitigate competition with maize (Zea mays L.) seedlings in a kura clover (Trifolium ambiguum Bieb.) living mulch (KCLM). This study investigated the effect of row-establishment and fertilizer nitrogen (N) rate on maize yield and N uptake in a KCLM system in Arlington, WI, and Rosemount, MN, during the 2021 growing season. Row establishment treatments included rotary zone tillage (RZT), shank strip-tillage (ST), and banded herbicides (BH), each evaluated at six N rates from 0 to 225 kg N ha−1. Extended periods of moderate and severe drought were experienced during the study period. The Arlington and Rosemount sites received 64 and 63% of the normal precipitation between 20 Apr. and 31 Oct. 2021, but poor distribution and higher temperatures at Rosemount elevated drought severity indices at that site. Grain yields at Rosemount were 3.6 Mg ha−1, whereas Arlington produced yields that matched expectations for the area (10 Mg ha−1). Row establishment affected maize grain yield differentially at each site, where, under severe drought conditions, BH maximized maize yield, whereas under moderate drought conditions, the higher level of tillage (RZT) maximized maize yield. These responses are most likely attributed to reduced moisture loss in the row-zone of the BH treatment and the greater level of clover suppression in the RZT treatment and their interactions with specific weather conditions at the research sites. Results from this study indicate that row establishment methods in a KCLM cropping system should be considered with spring environmental conditions and the expected weather outlook.
Alexander, J. R., Baker, J. M., & Venterea, R. T. (2023). Maize performance in a kura clover living mulch under drought conditions. Agrosystems, Geosciences & Environment, 6(1)https://doi.org/10.1002/agg2.20329
Estimating nitrogen inputs from a Kura clover living mulch system for maize production.
AimsKura clover living mulch (KCLM) is thought to provide in-season nitrogen (N) to the cash crop. Because of interactions between cropping system and crop performance, the magnitude of in-season N inputs from KCLM cannot be quantified using common N rate research methods. We aim to quantify the timing and magnitude of these N inputs using clover biomass and decomposition data.MethodsThis research measured the temporal distribution of clover biomass with intensive sampling, vertical biomass distribution using bead tracer analysis, and residue decomposition using in situ litter bags. These data were used as inputs to a model that estimated the in-season N contributions from KCLM.ResultsOur results found that spring management contributed 7–23 kg N ha−1 during the first 6 weeks of the growing season, while shade suppression contributed 59 – 84 kg N ha−1 from mid-June to mid-October. Daily N inputs peaked on 8 August at 1.14 kg N ha−1 d−1. When these estimates were added to fertilizer N inputs and analyzed against crop N uptake, we found that the maize took up 88% of the total N inputs and fertilizer recovery efficiency was 56%.ConclusionsThis study provides a methodology which generates estimates that may be used in research related to N cycling and management in KCLM and other legume intercropping systems.
Alexander, J. R., Venterea, R. T., & Baker, J. M. (2023). Estimating nitrogen inputs from a Kura clover living mulch system for maize production. Plant and Soil, 493(1-2), 237-248. https://doi.org/10.1007/s11104-023-06226-w