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Plain Language Summary: As profit margins become increasingly smaller for Midwest farmers, it is crucial to understand how a crop reacts to weather‐related stress. Cornfield edge effect is a new phenomenon Iowa farmers are experiencing where grain yield is lower at the field edge and progressively improves towards the field interior. Our objective was to verify if cornfield edge effect is occurring in Iowa along southern or western field edges when soybean is the adjacent field. And, if an edge effect is observed, determining the timing of the effect through the analysis of grain yield components. Field data collection was conducted in two regions of Iowa in 2019 and 2020 with observations at four distances from the field edge to interior. A field edge effect was detected in three of seven locations. We believe cornfield edge effect is occurring and that often it is a result of lower kernel numbers per ear and/or kernel weight. [ABSTRACT FROM AUTHOR]

Adverse weather conditions from acute events (e.g., storms causing lodging, flooding, or hail) or short‐duration weather patterns (i.e., periods of cold events; extended waterlogged field conditions) can result in yield losses, though management practices may play key roles in aiding with crop recovery or avoidance of these stress events. This review summarizes current knowledge (with emphasis placed on the US Midwest) related to corn response to short‐term weather stresses of (i) cold temperature, (ii) excess water, (iii) hail/defoliation damage, and (iv) wind damage. Each section presents summaries of how corn growth and yield are affected, provides context into past events experienced, identifies agronomic or production recommendations to correct or alleviate the stress condition, and proposes areas where future research is needed. This review also highlights challenges associated with controlled simulation work on these stressors, and also identifies key areas to expand future research efforts. In general, yield losses associated with strong storms and short‐term weather events often ranged from 5% to 35%, but extreme cases could result in up to 80%–100% yield loss. Much of the literature on these topics was published prior to 1995, though it still forms the basis for modern agronomic guidance, which is problematic given the changes in agriculture in the last 20 years in management practices, available genetics and technologies, and changing environmental conditions. Revisiting these foundational studies and expanding them to examine current and future weather conditions are critical for better informing agronomic recommendations, for devising mitigation strategies, and for determining accurate yield loss expectations following these stresses. Core Ideas: Climatic shifts are resulting in more frequent strong storms and adverse weather for corn.Storms and weather stress reduce corn yield 5%–35%, though greater losses are possible.Foundational knowledge produced prior to 1995 should be re‐assessed to ensure accuracy in modern systems.Updating agronomic recommendations with modern technology is critical to ensure crop security. [ABSTRACT FROM AUTHOR]

Background: A landscape‐scale probability‐based sampling of Iowa soybean [Glycine max (L.) Merr.] fields was conducted in 2013 and 2019; Amaranthus tuberculatus [Moq.] J.D. Sauer seed was collected from 97 random geospatial selected fields. The objectives were to evaluate the prevalence and distribution of herbicide‐resistant A. tuberculatus (waterhemp) in soybean fields and evaluate temporal changes over 6 years. Amaranthus tuberculatus seedlings were evaluated for resistance to imazethapyr, atrazine, glyphosate, lactofen and mesotrione at 1× and 4× label rates. Results: Resistance to imazethapyr, glyphosate, lactofen and mesotrione at the 1× rate increased significantly from 2013 to 2019 and was found in 99%, 97%, 16% and 15% of Iowa A. tuberculatus populations in 2019, respectively. Resistance to atrazine at the 4× rate increased over time; atrazine resistance was found in 68% of populations in 2019. Three‐way multiple herbicide‐resistant A. tuberculatus was the most frequent and increased significantly to 4× rates from 16% in 2013 to 43% of populations in 2019. All A. tuberculatus populations resistant to HPPD‐inhibitor herbicides also were resistant to atrazine. Conclusion: To the best of our knowledge, this is the first probability‐based study that presented evolution of A. tuberculatus herbicide resistance over time. The results demonstrated that imazethapyr, atrazine and glyphosate resistance in Iowa A. tuberculatus populations was frequent whereas resistance to lactofen and mesotrione was less frequent. Most Iowa A. tuberculatus populations evolved resistance to multiple sites of action over time. The results of our study are widely applicable given the similarities in weed management practices throughout the Midwest United States. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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Long‐term weather patterns (environmental conditions or stresses exceeding 10 days in length) have the potential to influence corn (Zea mays L.) growth, development, and yield. This review summarizes the current knowledge (with emphasis placed on the Midwestern U.S. production environment) on how long‐term weather conditions affect corn growth and yield, including (i) drought and heat stress, (ii) solar radiation, and (iii) distribution of heat unit accumulation during the season. Each section contains summaries of how these environmental factors influence corn growth and yield and provides context into past events experienced. The focus of the review is on dent corn grown for grain production, though relevant issues related to other types (i.e., silage corn) are included. This review also discusses agronomic recommendations or considerations to help alleviate the negative effects of stress conditions and identify areas where future research would be beneficial to continue improving the resiliency of corn cropping systems. Periods of high heat and water deficit as well as limited light availability challenge the ability to maximize yield production in corn. Temperature affects crop growth and development through the season, and accurately describing phenological progression using heat unit accumulation is a challenge. Advances in corn breeding and genetics, hybrid selection, and agronomic management practices will be key to ensuring long‐range productivity and fully leveraging possible benefits from the shifts in long‐range weather patterns. Core Ideas: Most current management strategies for addressing long‐term weather stress are employed preemptively.There is a continued need to improve upon current crop phenology models to accurately forecast crop development.Continued research on genetic × management interactions with the environment is essential to assess crop tolerance.Crop advances (e.g., breeding, hybrid selection, and agronomics) are key to ensure long‐range productivity from shift. [ABSTRACT FROM AUTHOR]

Herbicide‐resistant waterhemp (Amaranthus tuberculatus [Moq.] J.D. Sauer) continues to threaten the productivity of many US crops. Thus, integrating non‐herbicidal tactics with herbicides to reduce weed seedbanks is gaining popularity. A field study was conducted near Logan, IA from fall 2021 to fall 2022 to evaluate the impacts of cereal rye (Secale cereale L.) cover crop, herbicides, and harvest weed seed destruction on the waterhemp seedbank inputs. The cereal rye cover crop reduced waterhemp seed production by 90% compared to treatments without the cereal rye cover crop, while herbicides did not significantly affect waterhemp seed production. Furthermore, 96% of waterhemp seeds that entered the combine at harvest were destroyed and seed destruction effectiveness was not affected by cereal rye cover crop, herbicide program, or combine speed. Thus, cover crops and weed seed destruction are effective tactics to minimize waterhemp seedbank inputs. Waterhemp seed retention and combine header losses of waterhemp seeds were evaluated at harvest. Waterhemp seed retention was not affected by the cereal rye cover crop or herbicide programs. Only 30% of waterhemp seeds remained on the plant at harvest; the likely causes of seed shattering were late harvest and windy conditions prior to harvest. Waterhemp seed shattering from the combine header averaged 2.6% and was not affected by cover crop, herbicide program, or combine speed. These results support the inclusion of non‐herbicidal control tactics to reduce herbicide‐resistant waterhemp seedbanks and suggest the need for future research to optimize weed seed destruction. Core Ideas: Managing herbicide‐resistant waterhemp seedbank inputs with several agronomic practices was studied.Reducing waterhemp seed production with cereal rye cover crop residue was observed.The impact of agronomic factors such as cereal rye cover crop and herbicide program on waterhemp seed retention was determined.The impact of several agronomic factors and combine travel speed on waterhemp seed loss at the combine header was assessed.Damage effectiveness of weed seed destructor on waterhemp seed was evaluated. [ABSTRACT FROM AUTHOR]

Cover crops decrease nutrient leaching from high‐input cropping systems and improve soil quality. In Iowa, cereal rye (CR, Secale cereale L.) is the most adopted species due to its winter hardiness, high biomass productivity, and low cost. Field management of CR is still not completely understood, and as its adoption brings more complexity to farmers, especially with the uncertain effects on corn (Zea mays L.) yields, adoption is slow. Additionally, cover crops immobilize N and increase the inoculum of pathogens such as Pythium spp. A 2‐year field experiment was conducted at three locations in Iowa investigating the effect of two seeding methods, three seeding rates, and two termination timings (one location only) of CR on CR biomass and corn growth, root disease, and yield. Cereal rye biomass and consequently corn growth and development were not affected by seeding rate but by seeding method and termination timing. Broadcast CR produced an average of 3.5 times more biomass but 7.2% less corn yield than the drilled CR. Cereal rye when terminated late (3 days before planting [DBP]) produced 2.1 times greater biomass but 4.1% less corn yield compared to early termination (14 DBP). In general, greater root rot incidence and more Pythium clade B were detected in corn seedlings sampled from broadcast CR than drilled CR. Radicle rot incidence of corn was also greater in the late‐terminated plots in 1 year. Farmers should be careful using broadcast seeding and later termination of CR cover crop when planted before corn. Core Ideas: Spring cereal rye biomass accumulation was greatly affected by fall establishment.Corn growth and yield were negatively related to spring cereal rye biomass accumulation.Greater seedling disease occurred in corn planted into broadcast cereal rye.Farmers can benefit from using lower seeding rates to adopt cover crops while balancing costs.Drill seeding with early termination is a good strategy to balance cereal rye biomass and corn yield penalty. [ABSTRACT FROM AUTHOR]

It is widely recognized that planting soybean [Glycine max (L.) Merr.] early is critical to maximizing yield, but the influence of changing management factors when soybean planting is delayed is not well understood. The objectives of this research were to (a) identify management decisions that increase seed yield in either early‐ or late‐planted soybean scenarios, and (b) estimate the maximum break‐even price of each management factor identified to influence soybean seed yield in early‐ or late‐planted soybean. Producer data on seed yield and management decisions were collected from 5682 fields planted with soybean during 2014−2016 and grouped into 10 technology extrapolation domains (TEDs) based on growing environment. A subsample of 1512 fields was classified into early‐ and late‐planted categories using terciles. Conditional inference trees were created for each TED to evaluate the effect of management decisions within the two planting date timeframes on seed yield. Management strategies that maximized yield and associated maximum break‐even prices varied across TEDs and planting date. For early‐planted fields, higher yields were associated with artificial drainage, insecticide seed treatment, and lower seeding rates. For late‐planted fields, herbicide application timing and tillage intensity were related to higher yields. There was no individual management decision that consistently increased seed yield across all TEDs. [ABSTRACT FROM AUTHOR]

Delayed corn (Zea mays L.) harvest after physiological maturity (PM) is a universal practice in the U.S. Corn Belt to reduce grain drying cost. However, corn yield is speculated to be lost due to kernel dry matter loss from seed respiration. We evaluated the impact of in‐field dry down on corn dry matter content and grain quality after PM at two locations in Iowa during 2016 and 2017. Each site‐year consisted of two planting dates and three hybrids where ears were collected six to eight times from PM to harvest. Regardless of site‐year and hybrid, grain moisture decreased and test weight increased linearly with harvest dates and plateaued, on average, at 118 g kg–1 moisture and 752 kg m–3 test weight. Test weight was strongly associated with grain moisture. The standard test weight of 722 kg m–3 coincided with calendar dates around the first to second week of October. Kernel weight was unchanged and ear loss from lodging was minimal across harvest dates but differed among hybrids for each harvest date. These differences were not influenced by hybrid relative maturity (RM). Grain protein, oil, and starch concentrations were almost unchanged between PM and harvest though they were affected by the main and/or interaction effects between harvest dates and hybrids for most site‐years. Results suggest that corn can be harvested at any time after PM without any dry matter and quality penalties and harvest should be done based on grain moisture and standard test weight to minimize in‐field grain loss. [ABSTRACT FROM AUTHOR]

We used the Agricultural Production Systems sIMulator (APSIM) to predict and explain maize and soybean yields, phenology, and soil water and nitrogen (N) dynamics during the growing season in Iowa, USA. Historical, current and forecasted weather data were used to drive simulations, which were released in public four weeks after planting. In this paper, we (1) describe the methodology used to perform forecasts; (2) evaluate model prediction accuracy against data collected from 10 locations over four years; and (3) identify inputs that are key in forecasting yields and soil N dynamics. We found that the predicted median yield at planting was a very good indicator of end‐of‐season yields (relative root mean square error [RRMSE] of ∼20%). For reference, the prediction at maturity, when all the weather was known, had a RRMSE of 14%. The good prediction at planting time was explained by the existence of shallow water tables, which decreased model sensitivity to unknown summer precipitation by 50–64%. Model initial conditions and management information accounted for one‐fourth of the variation in maize yield. End of season model evaluations indicated that the model simulated well crop phenology (R2 = 0.88), root depth (R2 = 0.83), biomass production (R2 = 0.93), grain yield (R2 = 0.90), plant N uptake (R2 = 0.87), soil moisture (R2 = 0.42), soil temperature (R2 = 0.93), soil nitrate (R2 = 0.77), and water table depth (R2 = 0.41). We concluded that model set‐up by the user (e.g. inclusion of water table), initial conditions, and early season measurements are very important for accurate predictions of soil water, N and crop yields in this environment. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizer application to soybean [Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results. We performed a study in central Iowa (2015 and 2016) to investigate the effect of N fertilizer rate (0, 45, 90, 135 kg N ha−1) and application timing (planting, flowering, pod setting) on soybean yield, yield components, and to calculate the economic net return to N fertilizer. Results showed a positive effect of N fertilizer on soybean yield and yield components both years. Seed and aboveground biomass dry weight were positively correlated to N fertilizer, and both were 17% greater than No‐N treatment. Nitrogen fertilizer rate that significantly increased seed and aboveground biomass was 135 kg N ha−1 regardless of application timing (2015), or at planting (2016). Moreover, the same N fertilizer addition applied at planting benefitted seed and aboveground biomass N accumulation only in 2016 (avg. 32.00 and 34.68 g N uptake m−2, respectively), both 1.5‐times higher than No‐N treatment. Favorable environmental conditions during 2016 lead to hand‐measured yield difference of 22% compared to 2015. Economic net return analysis showed that the additional revenue from increased yield attributed to supplemental N fertilization offset the application cost, resulting in net return gains between US$5.83 to $281.89 ha−1 (all treatments except 45 kg N ha−1 on 2015). This study highlights the importance to parse out soybean yield in its components, and the need to quantify yield gains from N fertilizer additions in economic terms which shed some light on any tradeoffs. [ABSTRACT FROM AUTHOR]

This study investigated the efficacy of: (a) delayed feedback; (b) delayed feedback and social reinforcement; or (c) delayed feedback, social reinforcement, and tangible reinforcement for reducing the rate of bizarre motoric behaviors for 2 female and I male chronically institutionalized mental clients. These treatments were consecutively employed with each subject, utilizing a multiple baseline across subjects experimental design. Results indicated that these subjects were able to retain and understand the feedback on both their problem and alternative behaviors but that reductions in the inappropriate motoric behaviors resulted only when tangible reinforcers were included in the treatment. Implications for further investigations and for the utility and efficiency of delayed feedback and reinforcement with chronically institutionalized adults are discussed. [ABSTRACT FROM AUTHOR]

The ability of two female and one male chronically institutionalized adult mental patients to comprehend and retain feedback on individualized problem behaviors and the effect of that feedback on changes m the occurrences of those behaviors were examined. Feedback on five problem behaviors was provided to each subject within a small therapy group setting employing a multiple baseline across subjects experimental design. Comprehension and retention tests occurred two, five, and seven days following the feedback in the small groups, while the rates of the occurrences of the problem behaviors were time-sampled throughout the subjects' waking day via use of the Time-Sample Behavioral Checklist (Paul, 1987). Results indicated that, although there were no changes in the rates of occurrence, these subjects were able to retain and understand the feedback on their problem behaviors. Implications for further investigations and for the utility of feedback with chronically institutionalized adults are discussed. [ABSTRACT FROM AUTHOR]