Crop, Forage and Turfgrass Management最新文献

Wide-spread adoption of proximal sensors in crop health assessment requires understanding of changes in canopy reflectance during the growing season and associations among readings from different sensors. Chlorophyll meter reading (Soil Plant Analysis Development, SPAD), red normalized difference vegetation index (RNDVI), and red-edge normalized difference vegetation index (RENDVI) were measured for sugarbeet (Beta vulgaris L.), corn (Zea mays), sunflower (Helianthus annuus L.), soybean (Glycine max), and spring wheat (Triticum aestivum) throughout the 2021 growing season. Cumulative growing degree days (GDD) had a significant relationship with SPAD, RNDVI, and RENDVI. The correlation coefficient indicated SPAD was more associated with RENDVI (r = 0.73) than RNDVI (0.50). The R² values of multiple linear regression of SPAD and GDD with RNDVI and RENDVI were the lowest for spring wheat (0.33 and 0.52, respectively) and the highest for corn (0.94 and 0.95, respectively). For all major five crops grown in the Northern Great Plains, GDD showed a strong relationship with all three indices. For in-season crop health assessment based on vegetation indices, inclusion of GDD could be a useful predictor variable to develop a single model algorithm applicable for multiple crops at a regional scale.

Seed treatments are commonly used to protect most major crops in the United States from seed- and soil-borne pathogens. In winter wheat (Triticum aestivum L.) systems in the North Central United States, target pathogens include both true fungi like Fusarium spp. or Rhizoctonia spp. and oomycetes like Pythium spp. or Globisporangium spp. Potential benefits of seed treatments may include improved germination and emergence, protection against early season diseases, and improved plant vigor, but there is little recent research on the benefits of seed treatments in winter wheat in the North Central United States. Field experiments were established at 10 locations across Wisconsin, Indiana, and Michigan in 2021 and 2022 to evaluate the effect of seed treatments on winter wheat yield. The trial design was a randomized complete block with four replications. Treatments were a factorial of two varieties, Harpoon and Kaskaskia, and five seed treatments, non-treated control, Athena-R, CruiserMaxx Vibrance Cereals, Stamina F4, and Raxil Pro MD/Shield. The variety Harpoon resulted in greater yield and lower test weight than Kaskaksia. The only seed treatment to affect yield was Athena-R when applied to the Harpoon variety. No other seed treatment significantly impacted yield. Results of this study suggest that while seed treatments can provide yield protection, variety selection had a bigger role in overall yield potential.

Furrow-irrigated rice (FIR; Oryza sativa L.) has been grown in the upper Mid-South since the 1980s. Nitrogen use in FIR is less efficient than direct-seeded, delayed-flood rice due to the lack of a flood, which ultimately protects applied nitrogen (N) from nitrification and subsequent denitrification. If urea applied to FIR fields could be protected from nitrification, N use efficiency could be increased. To address this issue, a test was initiated in 2018 to determine the utility of a blended-urea product that included < 0.1% N-butyl-thiophosphoric triamide (NBPT), a urease inhibitor that is recommended on most urea applications to rice, and 0.85% dicyandiamide (DCD), a nitrification inhibitor. A control with no supplemental N application plus six different N management programs were tested as urea + NBPT with or without DCD. Analyses across six sites over 2 years suggested that DCD did not affect any of the variables measured, including total N uptake, recovery efficiency of N, rice grain yield, and rice milling yield. While this is contrary to some previous studies, the product used in the current study contained approximately 10 times less DCD than previous studies in rice. Therefore, out of the products tested, the authors recommend purchasing the lowest cost option.

No-tillage (NT) soybean [Glycine max (L.) Merr.] following corn (Zea mays L.) is a common practice in the United States. It reduces production costs associated with tillage such as labor, fuel, and equipment, in addition to providing environmental benefits such as reduced erosion and carbon emissions. However, in some situations, NT soybean seed yield can be reduced compared to conventional tillage (CT). The objectives of this study were to (i) quantify the effects of nitrogen, corn residue management, and tillage on soybean seed yield, and (ii) recommend optimal residue and nitrogen (N) management strategies for NT soybean following corn. The study was conducted at the University of Wisconsin-Madison Arlington Agricultural Research Station near Arlington, WI, during the 2022 and 2023 growing seasons. Treatments were tested in a randomized complete block design with four replicates. Treatments were combinations of NT, CT, N fertilizer application, and corn residue management (removed, chopped, or none). Soybean seed yield was not affected by removing corn residue. Applying 30 lbs N acre⁻¹ prior to NT planting soybean into corn residue and CT increased seed yield by 4.1 bu acre⁻¹ (6.1%) and 5.3 bu acre⁻¹ (7.8%), respectively compared to NT soybean planted into corn residue. The addition of a low rate of spring N can be a tool for producers to increase NT soybean seed yield rather than performing tillage.

North Carolina soybean [Glycine max (L.) Merr.] growers use a diverse range of row spacings, commonly between 7.5 and 38 inches. Research findings regarding the effect of row spacing on soybean yield have been inconsistent and influenced by factors such as planting date and environmental conditions. Although small-plot data from North Carolina often indicates that narrower row spacings lead to higher yields, growers have raised concerns about the potential benefits of wide rows when ripping is employed in environments exhibiting symptoms of subsurface compaction. Research was conducted over 2 years (2021–2022) in the Coastal Plain region to evaluate the effects of wide row ripped spacing (36 or 38 inches) compared to un-ripped narrower spacing (15 inches) on plant population, canopy cover, soil compaction, and yield across four environments. One of the environments included an additional treatment with an un-ripped drilled row spacing of 7.5 inches. Although seeding rates were calibrated similarly, the ripped wide-row spacing treatments led to lower achieved plant population, predominantly due to adverse seed bed conditions resulting in lower germination caused by the inline ripper. The un-ripped narrow row spacings (7.5 and 15 inches) consistently demonstrated 7–25% greater canopy cover than ripped wider spacings (36 and 38 inches) by the flowering stage (R1). Soil penetration resistance varied by row spacing in only two environments, with differences generally lacking agronomic significance (i.e., penetration resistance <2 MPa). Yield results indicated no significant effect of row spacing in three out of four environments; in the fourth environment, the un-ripped 15-inch row spacing yielded significantly more than both the un-ripped drilled and ripped wide-row soybeans. In the environments in this study, wide-row ripped treatments offered no agronomical advantage over narrow row un-ripped treatments.

Buckwheat (Fagopyrum esculentum) is a fast-growing plant that quickly produces a dense groundcover. The utilization of buckwheat as a cover crop in vegetable production could be beneficial to Georgia producers, however for successful adoption, weed control in the cover crop coupled with control of buckwheat volunteers must be achievable. A preemergence (PRE) and a postemergence (POST) experiment were each conducted three times in Ty Ty, GA (2020–2021) addressing these objectives. In the PRE study, acetochlor at 0.56 lb ai acre⁻¹ injured buckwheat up to 16% without negatively influencing growth, suggesting potential for use in buckwheat for weed control. Flumioxazin, fomesafen, halosulfuron, ethalfluralin and S-metolachlor lacked adequate buckwheat safety. However, flumioxazin at 0.05 lb ai acre⁻¹, fomesafen at 0.19 lb ai acre⁻¹, and halosulfuron at 0.02 lb ai acre⁻¹ were identified as effective options to manage volunteer plants, as control exceeded 80%. In the POST experiment, buckwheat injury from 2,4-D, clethodim, dicamba, glufosinate, glyphosate, halosulfuron, linuron, paraquat, and prometryn was evaluated, and when considering all evaluation parameters, paraquat (0.50 lb ai acre⁻¹) was the most effective option for the control of buckwheat. This was followed by glufosinate (0.59 and 1.17 lb ai acre⁻¹) and glyphosate (1.20 and 2.40 lb ai acre⁻¹). For potential applications over buckwheat for weed management, clethodim (0.12 lb ai acre⁻¹) was the only POST herbicide that provided adequate crop safety.

Though costly, pasture restoration is necessary when forage stands decline. Interseeding legumes (e.g., alfalfa, Medicago sativa L.), along with crabgrass (CG; Digitaria sanguinalis L.) as a warm-season forage with high nutritive value, can play a key role in supporting pasture restoration. Our objective was to quantify changes in forage mass (FM) and nutritive value and the associated cost of pasture restoration using different strategies. The experiment was carried out in Spring Hill, TN, for 2 years in established swards of tall fescue [TF; Schedonorus arundinaceus (Schreb.) Dumort] or orchardgrass (OG; Dactylis glomerata L.), with the addition of alfalfa with or without CG. The treatments were: 1) control (C-TF or C-OG), 2) synthetic N fertilization (TF+N or OG+N), 3) fall seeding of alfalfa (FA), 4) spring seeding of alfalfa (SA), 5) fall seeding of alfalfa + summer seeding of CG (FA+CG), and 6) spring seeding of alfalfa + summer seeding of CG (SA+CG), with four replications. The FM was greatest when N fertilizer was applied to TF and OG. In both grass types, N fertilization also resulted in greater nutritive value than the control. The addition of alfalfa and CG did not result in an increase in nutritive value, and this response probably may be pronounced in the medium to long term when overseeded species are well established. Thus, synthetic N still incorporates greater outcomes, showing the need for long-term researchers to provide deeper information into overseeding cool- and warm-season grasses, thereby contributing to the restoration of ecosystems.

Relative maturity (RM) selection is important for corn (Zea mays L.) farmers because it has significant effects on yield and profit. Selecting the appropriate RM is particularly important for corn farmers in the northern Corn Belt where growing season length is often a limiting factor. However, there is limited information on optimal RM for maximizing yield and partial returns in Michigan and other northern states. The objective of this study was to examine optimal RM across Michigan over the last two decades to identify RM that maximizes yield and partial returns. Data from irrigated and dryland corn hybrid trials conducted in Michigan between 2006 and 2022 were analyzed. Partial returns were estimated at a single grain price ($4.38 bu⁻¹) and two drying costs ($0.045 and $0.06 bu⁻¹ point⁻¹). Our results showed that optimal RMs remained similar for most years (14 out of 17) and decreased significantly in 2009, 2014, and 2019. Averaged across years, optimal RMs for maximum yield were lowest (ranged from 84 to 95) in northern locations (latitude >44°N) and highest (ranged from 104 to 109) in the south (latitude 42°N). The optimal RM for maximum partial returns was up to 3 units lower than that maximized yield for central and southern locations but showed variability in northern locations. Overall, our results provide useful regional recommendations for Michigan corn farmers to optimize RM selection.

Early in the growing season, abiotic (freezing temperatures, hail, flooding, etc.) and biotic (slugs, deer, disease, insects, etc.) factors often reduce soybean [Glycine max (L.) Merr.] plant populations. Although seeing a soybean field with poor seedling vigor, slow plant growth, and low plant population density often triggers an urge to replant, such fields do not always need to be replanted. The objectives of this management guide are to (a) address the necessary considerations prior to replanting a soybean field; (b) provide images depicting common early season stressors affecting soybean; and (c) explain the potential yield limitations from early season soybean injuries. US soybean agronomists representing a diversity of growing regions collated replant guidelines to generate applicable recommendations and pictures showing effects of early-season stressors that reduce soybean plant population. The minimum soybean stand required to produce near-maximal yields has been as low as 50,000 plants per acre, but more plants than that may be required in the case of adverse growing conditions, in northern regions, or with early-maturing varieties. When the plant population is low, repair planting—adding seeds without destroying established plants—portions of the field instead of destroying the existing stand and starting over is recommended. Management in reaction to stand loss should consider the cause and type of damage and should focus on maximizing profitability.

Silage corn (Zea mays L.) in Michigan and the Great Lakes region is prone to an emerging foliar disease called tar spot (caused by Phyllachora maydis). When corn is infected with Phyllochora maydis, stromata develop on the leaves resulting in early senescence and drying. Therefore, to understand the effect of tar spot on forage yield, nutritive value, and predicted milk yield, field trials were conducted at multiple Michigan locations from 2021–2023. Field trials were arranged in randomized complete block design with four replications. Treatments included hybrid resistance (one susceptible and one partially resistant hybrid) and three fungicide treatments using Delaro 325 SC at 8 oz acre⁻¹ (non-treated, one application at silking [R1], and two applications [one at R1 and second at dough stage]). Results showed that tar spot severity increased over time in silage corn. Fungicide application in susceptible hybrid had the lowest tar spot severity across all hybrids and fungicide treatments. Hybrid disease resistance resulted in 50% reduction of tar spot severity and contributed to a lower yield penalty. Reduction of tar spot severity due to hybrid disease resistance also minimized decline in neutral detergent fiber digestibility and predicted milk yield. Fungicide application reduced tar spot severity but did not affect dry yield and forage nutritive value. Overall, our study shows that tar spot reduces forage yield and nutritive value and requires an integrated approach to disease management.