Risk Of Yield Loss Research Articles

Scientific evidence of sustainable plant disease protection strategies for oilseed rape (Brassica napus) in Sweden: a systematic map

BackgroundOilseed rape (OSR; Brassica napus L.) is a highly valued crop for food, feed and industrial use. It is primarily grown in temperate climates, and over recent decades, its area of production and profitability have increased. Concurrently, several diseases negatively impact OSR production. Diseases caused by soil-borne pathogens, pose a risk of substantial yield loss since crop rotation schemes have become narrow as the time lapse between OSR crops in a field has been shortened. The aims of this paper were to provide an overview of plant protection measures available for OSR production and to identify knowledge gaps and areas where more research is needed.MethodsThis systematic map builds on a previously published protocol and follows the ROSES reporting standard. The search strategy was developed in collaboration with stakeholders and designed to cover available scientific evidence for OSR disease management in climate zones relevant for Scandinavian crop production (Dfc, Dfb, Cfb and Cfa in the Köppen-Geiger climate classification). Five scientific databases were used to identify peer-reviewed literature, complemented by additional searches performed in grey literature. Articles were screened at three stages: the title, abstract and full text. The eligible publications included studies of OSR crops, and all measures to control crop disease in agricultural fields were considered eligible interventions. The comparator was intervention and no intervention, and the yield per unit area, disease suppression or an increase in crop quality were determined to be outcomes of interventions. A basic assessment of the experimental design of each study was performed to assess its eligibility. All articles were coded based on the following categories: the location and climate zone, disease, pathogen, intervention and management method, outcome and study design. Articles not reporting original data but judged to be relevant (i.e., review papers, books and notes of registration of cultivars) were saved in a separate category called “books, reviews and reports”.Review findingsA total of 4633 articles were collected through systematic searches. After duplicates were removed, 3513 articles were included in the screening process. After screening at the title and abstract levels, 897 articles were evaluated at the full text level, and 118 articles comprised the studies that met the eligibility criteria of the systematic map. The country (Canada) and region (Europe) with the largest OSR crop production areas also contributed the highest number of articles. In total, 17 different diseases were reported, with black leg (syn. Phoma stem canker) being the most studied disease. Nineteen different intervention methods or management types were examined. Cultivar resistance and pesticide application were the most studied control measures.ConclusionWe report scientific studies on plant disease protection measures for OSR based on field trials where the results are intended to be directly implemented in crop production management. The map clearly provides an overview of research progress throughout the time period chosen, and it identifies knowledge gaps regarding important diseases where only a few studies have been published, for example, diseases caused by viruses.

Methodical approach to assessing risks of possible yield losses during implementation of agricultural technologies

The methods of risk assessment and decision-making in the management of agrotechnology were studied in order to develop a methodical approach to assessing the risks of possible yield losses in case of deviations from the project parameters in the implementation of agrotechnology. The study uses methods of analyzing information from the subject area of risk management in the management of agricultural technology. A registry of possible deviations in the design values of process parameters in the implementation of agricultural technologies has been compiled. A new approach has been developed to assess the risks of possible yield losses in the implementation of agrotechnology with deviations in process parameters from project values. Using the proposed approach will provide an automated ranking of options for decisions on the degree of risk of possible crop failure in case of deviations from the designed values, which will facilitate the transition to intelligent management of crop production.

Optimizing weed control using dicamba and glufosinate in eligible crop systems

AbstractA field experiment was conducted in 2019 and 2020 that included six site-years and four locations in Arkansas to determine the optimal sequence and timing of dicamba and glufosinate applications when applied alone, sequentially, or in combination to control Palmer amaranth by size: labeled (<10 cm height) and non-labeled (13 to 25 cm height). Single applications of dicamba, glufosinate, and dicamba plus glufosinate (not labeled) resulted in less than 80% Palmer amaranth control, regardless of weed size. The mixture of dicamba plus glufosinate was antagonistic for Palmer amaranth control and percent mortality. Sequential applications, averaged over all time intervals and herbicides, improved the percentage of Palmer amaranth control 11 to 17 percentage points over a single application, regardless of weed size at application 28 d after final application (DAFA). Palmer amaranth control with glufosinate followed by (fb) glufosinate and dicamba fb dicamba, pending weed size, were optimized at intervals of 7 d, and 14 to 21 d, respectively. Because single site of action (SOA) postemergence herbicide systems increase the likelihood of the development of resistant biotypes and are not a best management practice (BMP) in that regard; sequential applications involving both dicamba and glufosinate were more effective. Furthermore, the sequence of application mattered with a preference for applying dicamba first. Dicamba fb glufosinate at a 14-d interval was profit-maximizing and the only herbicide treatment that resulted in 100% weed control when size was <10 cm. For larger weed sizes, economic analysis revealed that dicamba fb dicamba performed better than dicamba fb glufosinate when no penalty was assigned for using a single SOA. This resulted in greater yield loss risk and soil weed seed bank in comparison to timelier weed control with the smaller weed size. Hence, timely weed control and two SOAs to control Palmer amaranth are recommended as BMPs that reduce producer risk.

Ivyleaf morningglory (Ipomoea hederacea Jacq.) competition is not intensified by drought in silage corn in central New York State, USA

Ivyleaf morningglory (IMG, Ipomoea hederacea Jacq.) is a summer annual vine that is native to the Americas and invasive globally. This species decreases field crop yields through competition and interference with harvesting. Here, we explore the potential of IMG to compete with silage corn ( Zea mays L.) in New York State, USA. In a 2-year field study, we measured silage yield at five IMG planting densities (0–8 plants m−2) under no-drought conditions and a drought treatment established with rainout shelters. Volumetric water content was 26%–28% lower in the drought treatment than the no-drought treatment. Drought reduced fresh corn silage yield ( P = 0.003). Fresh silage yield was 21 600 ± 700 kg ha−1 in the no-drought treatment in 2016, 19 100 ± 900 kg ha−1 in the drought treatment in 2016, 30 500 ± 900 kg ha−1 in the no-drought treatment in 2017, and 28 200 ± 700 kg ha−1 in the drought treatment in 2017. Silage yield was not strongly responsive to IMG density, regardless of drought. These data suggest that the risk of corn silage yield losses due to IMG is relatively low in New York State and unlikely to be affected by drought. The risk posed by IMG may differ in other cropping systems or regions and under climate change.

Evaluation of Fusarium Head Blight Resistance in 410 Chinese Wheat Cultivars Selected for Their Climate Conditions and Ecological Niche Using Natural Infection Across Three Distinct Experimental Sites.

Exploiting wheat cultivars with stable resistance to Fusarium Head blight (FHB) and toxin accumulation is a cost-effective and environmentally friendly strategy to reduce the risk of yield losses and contamination with mycotoxins. To facilitate the deployment of stable cultivar resistance, we evaluated FHB resistance and resistance to mycotoxin accumulation in 410 wheat lines bred by local breeders from four major wheat growing regions in China after natural infection at three distinct locations (Hefei, Yangzhou and Nanping). Significant differences in disease index were observed among the three locations. The disease indexes (DI’s) in Nanping were the highest, followed by Yangzhou and Hefei. The distribution of DI’s in Yangzhou showed the best discrimination of FHB resistance in cultivars. Growing region and cultivar had significant effect on DI and mycotoxins. Among the climate factors, relative humidity and rainfall were the key factors resulting in the severe disease. Even though most cultivars were still susceptible to FHB under the strongly conducive conditions applied, the ratio of resistant lines increased in the Upper region of the Yangtze River (UYR) and the Middle and Lower Region of the Yangtze River (MLYR) between 2015 and 2019. Deoxynivalenol (DON) was the dominant mycotoxin found in Hefei and Yangzhou, while NIV was predominant in Nanping. Disease indexes were significantly correlated with DON content in wheat grain.

Likelihood of Extreme Early Flight of Myzus persicae (Hemiptera: Aphididae) Across the UK.

Myzus persicae (Sulzer, Hemiptera: Aphididae) is a major global crop pest; it is the primary aphid vector for many damaging viruses and has developed resistance to most insecticides. In temperate regions, the risk of widespread crop infection and yield loss is heightened following warm winters, which encourage rapid population growth and early flight. Estimates of the frequency and magnitude of warm winters are, therefore, helpful for understanding and managing this risk. However, it is difficult to quantify the statistical distribution of climate events, particularly extremes, because climate observations represent just a small sample of the possible climate variations in a region. The purpose of this study was to establish a large-scale relationship between temperature and M. persicae observations across the UK and apply this to a very large ensemble of climate model simulations, which better sample the variability in climate, to quantify the current likelihood of extreme early M. persicae flight across the UK. The timing of M. persicae flight was shown to be significantly related to January-February mean temperature, where a 1°C warmer/cooler temperature relates to about 12 d earlier/later flight. Climate model simulations predict 40% likelihood of experiencing a year with unprecedented early M. persicae flight during the next decade in the UK. Results from this method can help crop managers assess the long-term viability of crops and management practices across the UK and provide early warning information for targeting pest surveillance activities on the locations and timings at highest risk of early M. persicae flight.

Determination of Critical Weed Competition Period in Chamomile (Matricaria chamomilla L.) Production at Wondo Genet, Southern Ethiopia

The study was carried out at Wondo Genet to determine the critical weed competition period for growth, yield, and yield components of the chamomile plant. The weed competition duration had a significant influence on plant height, the number of primary branches/plants, fresh stem yield/plant, fresh leaves yield/plant, fresh and dry flower/plant, fresh and dry flower yield/ha, essential oil content (v/w) and yield kg/ha. The highest fresh and dried flower yield (3780.10 kg/ha) and (798.32 kg/ha) was recorded from weed-free check followed by weed-free for 60 DACE (Days After Crop Emergence) (3652.10 kg/ha) and (789.43 kg/ha), respectively. The maximum essential oil content and yield were recorded from the weed-free check (0.79v/w) and (6.25 kg/ha) whereas the minimum was in the weedy-check (0.10 v/w) and (0.15kg/ha), respectively. The yield losses of chamomile were estimated based on the fresh and dry flower and essential oil yield per hectare. Thus, the highest fresh and dry flower yield losses were recorded from the weedy-check (83.58%) and (81.05%) while the lowest was from weed-free check (0.00%), respectively. The highest essential oil yield loss was also recorded from the weedy for 60DACE (97.92%) followed by weedy-check (97.60%). To determine the beginning and the end of the critical period of crop-weed competition 5 and 0% acceptable yield loss levels were used. Therefore, to reduce the yield losses of chamomile by more than 10% and higher economic return, plants must be kept weed-free within 40 to 60DACE to reduce the risk of economic yield losses as it is the critical period of weed-crop competition in chamomile plants.

The Yield of M7 Mentik Wangi Rice Irradiated With Several Doses of Gamma Rays Under Drought Stress

The possible risk of yield losses due to drought stress could threaten rice production and national food security. One way to deal with drought limitations is by developing drought- tolerant varieties using gamma-ray irradiation. This research aimed to get the optimal dose of gamma-ray radiation to create an M7 generation of Mentik Wangi variety that is drought tolerant. Field experiments were conducted from December 2020 to March 2021 at the Screen House of the Faculty of Agriculture, Universitas Sebelas Maret, Surakarta, the Laboratory of Soil Physics, and the Laboratory of Plant Production Management, Faculty of Agriculture, Universitas Gadjah Mada. This study has carried out using a Randomized Complete Block Design with two factors. The first factor is gamma-ray irradiation dose (0gy. 100gy, 200gy, 300gy), and the second factor is drought stress treatment (without drought stress and drought stress in the flowering stage) with three replications. The results showed no interaction between gamma-ray irradiation dose and drought stress on all observed variables except plant dry matter. Drought stress in the flowering stage increased the percentage of unfilled grain, reducing the harvest index and grain weight significantly by 40.9%. Gamma-ray irradiation in a range of 100 to 300 gy did not affect panicle numbers and length, also the percentage of unfilled grain, but reduced the number of grains per panicle, thereby reducing the harvest index and grain weight 45.0% compared to those without irradiation.

Probabilistic modeling of crop-yield loss risk under drought: a spatial showcase for sub-Saharan Africa

Assessing the risk of yield loss in African drought-affected regions is key to identify feasible solutions for stable crop production. Recent studies have demonstrated that Copula-based probabilistic methods are well suited for such assessment owing to reasonably inferring important properties in terms of exceedance probability and joint dependence of different characterization. However, insufficient attention has been given to quantifying the probability of yield loss and determining the contribution of climatic factors. This study applies the Copula theory to describe the dependence between drought and crop yield anomalies for rainfed maize, millet, and sorghum crops in sub-Saharan Africa (SSA). The environmental policy integrated climate model, calibrated with Food and Agriculture Organization country-level yield data, was used to simulate yields across SSA (1980–2012). The results showed that the severity of yield loss due to drought had a higher magnitude than the severity of drought itself. Sensitivity analysis to identify factors contributing to drought and high-temperature stresses for all crops showed that the amount of precipitation during vegetation and grain filling was the main driver of crop yield loss, and the effect of temperature was stronger for sorghum than for maize and millet. The results demonstrate the added value of probabilistic methods for drought-impact assessment. For future studies, we recommend looking into factors influencing drought and high-temperature stresses as individual/concurrent climatic extremes.

Exploring hyperspectral reflectance indices for the estimation of water and nitrogen status of spinach

Optimizing irrigation and nitrogen (N) fertilizer management in vegetable production is key to meeting economic and ecological demands. Inadequate application increases the risk of quality and yield losses as well as environmental pollution. Accurate determination of both crops' water and N supply status is essential for an effective management strategy that couples N and water supply, thus accounting for the water–N interaction. In a field experiment with spinach as model crop, hyperspectral reflectance was measured and related to the relative water content (RWC), nitrogen and chlorophyll (Chl) content of leaves indicating plants' supply status. Three statistical methods were applied to estimate plants’ water and N status by reflectance spectroscopy: i) Published Vegetation Indices (VI) for N and water status, ii) Competitive Adaptive Reweighted Sampling - Partial Least Squares Regression (CARS-PLSR) to identify key wavelengths and to build a simple robust model based on full spectra, and iii) inflection points (IP) based on the first and second derivatives. The best model fit for Chl was obtained for VI REIP and IP1. For N, best results were found for mrNDVI and IP1. The estimation of RWC was not significant. Higher Chl content was found in stressed plants due to smaller and thicker leaves. At full water supply, REIP and IP1 as well as CARS-PLSR differentiated N status levels. In water-deficient plants, VIs and IPs successfully detected water stress levels. The basis for a differentiating nitrogen and water management using spectral data has been established.

The effect of COVID-19 outbreak on the competitive and comparative advantages of rice production in West Java, Indonesia

Food security is one of the keys to success in overcoming problems arising impact of the COVID-19 outbreak. Attention to the paddy production in West Java is imperative. This paper aimed to discuss the effect of the COVID-19 pandemic on the competitiveness of rice production in West Java by using two indicators of Policy Analysis Matrix (PAM), namely Private Cost Ratio (PCR) and Domestic Resource Cost Ratio (DRC). The data used is from the National Panel of Farmers (PATANAS) survey data for wetland rice agro-ecosystem in West Java, with 144 households of rice farmer respondents. The results show that the COVID-19 outbreak harms the competitiveness of rice production, and it takes three years for recovery to be a competitive advantage and more than five years for comparative advantage. At the private and social prices of GKP at the farm level equal to the GPP 2020, rice production in West Java will lose its competitive advantage starting in 2022, while the comparative advantage of rice production in West Java continues to decline until 2024. This study has three policy implications: the first eliminating disruption of the distributions of agricultural inputs and outputs. The second is striving to increase the use of machinery and equipment to secure the risk of yield loss during cultivation, harvest time, and post-harvest handling at the farm level. The third is selecting the farmers who have high capability in competitive and comparative advantages as a model for fostering competitiveness improvement for farmers with lower abilities.

Projection of future drought and its impact on simulated crop yield over South Asia using ensemble machine learning approach

Understanding the development mechanism of drought events, characterization of future drought metrics, and its impact on crop yield is crucial to ensure food security globally, and more importantly, in South Asia. Therefore, the present study assessed the changes in future projected drought metrics and evaluated the future risk of yield reduction under drought intensity. We characterized the magnitude, intensity, and duration of future drought by means of the SPEI drought index using CMIP6 (Coupled Model Inter-comparison Phase-6) climate models. The impact of future drought on crop yield was quantified from the ISI-MP (Inter-Sectoral Impact Model Inter-comparison Project) crop model by a proposed non-linear ensemble of Random Forest (RF) and Gradient Boosting Machine (GBM). Results suggested that high drought magnitude with a longer drought duration is projected in some regions of South Asia while high drought intensity comes with a shorter duration. It was also found that Afghanistan, Pakistan, and India will experience a longer drought duration in the future. Our proposed ensemble machine learning (EML) approach had high predictive skill with a minimum value of RMSE (0.358–0.390), MAE (0.222–0.299), and a maximum value of R2 (0.705–0.918) compared to the stand-alone methods of RF and GBM for yield loss risk projection. The drought-driven impact on crop yield demonstrates a high risk of yield loss under extreme drought events, which will encounter 54.15%, 29.30%, and 50.66% loss in the future for rice, wheat, and maize crops, respectively. Furthermore, drought and yield loss risk dynamics suggested a one unit decrease in SPEI value would lead to a 14.2%, 7.5%, and 10.9% decrease in yield for rice, wheat, and maize crops, respectively. This study will provide a notable direction for policy agencies to build resistance to crop production against the drought impact in the regions that are critical to climate change.

Managing water table depth thresholds for potato subirrigation

Subirrigation requires precise control of the water table level to provide adequate soil water content (SWC) for promoting plant growth. Optimizing water table level management has been shown to improve soil aeration, reduce N-leaching, and reduce risk of crop losses. The objectives of this study were to: i) assess if water table level and N-fertilizer rate impact potato growth, root development, plant N uptake, or tuber yield; and ii) estimate the optimum water table level threshold that provides sufficient soil upward water flux to meet plant water requirements. The study was conducted in 2013 and 2014 in Hastings, FL, USA. Water table level was automatically controlled in three independent irrigation zones of 1.4 ha at 36, 54, and 71 cm from the top of the hilled row, termed as high (HWT), medium (MWT), and low (LWT) water table treatments, respectively, and SWC measured at 22 cm depth was used as covariate to compare treatments. A randomized complete block with three replications was used to evaluate potato cultivars ‘Atlantic’ and ‘FL1867′ under 0, 112, 224, and 336 kg ha−1 of N-fertilizer within water table treatments. Marketable yield in 2013 was lower than 2014, owing to the high precipitation (421 mm) during tuber bulking that led to high SWC and tuber decay. Total and marketable tuber yields were maximized when N fertilizer rates ranged from 243 to 336 kg ha−1. The highest yield and proportion of large tubers occurred when SWC at 22 cm ranged from 0.13 to 0.16 m3 m−3. The HWT significantly limited root length, diameter, and surface area, compared to the LWT. In 2014, variation of SWC at 22 cm depth had little effect on tuber yield. The HWT was not detrimental to tuber yield, but rather it compounded the negative effect that high precipitation rate had on fluctuating SWC in the root zone, resulting in reduced yield and tuber quality. Optimal SWC in the root zone can be achieved by adjusting the water table level and upward soil water flux throughout the season, according to the crop evapotranspiration for each crop stage, which reduces irrigation water requirements and minimizes the risks of soil water saturation and tuber yield losses.

Diminishing weed control exacerbates maize yield loss to adverse weather.

Both weed interference and adverse weather can cause significant maize yield losses. However, most climate change projections on maize yields ignore the fact that weeds are widespread in maize production. Herein, we examine the effects of weed control and weather variability on maize yield loss due to weeds by using machine learning techniques on an expansive database of herbicide efficacy trials spanning 205 weather environments and 27 years. Late‐season control of all weed species was the most important driver of maize yield loss due to weeds according to multiple analyses. Average yield losses of 50% were observed with little to no weed control. Furthermore, when the highest levels of weed control were not achieved, drier, hotter conditions just before and during silking exacerbated maize yield losses due to weeds. Current climate predictions suggest much of the US maize‐growing regions will experience warmer, drier summers. This, coupled with the growing prevalence of herbicide resistance, increases the risk of maize yield loss due to weeds in the future without transformational change in weed management systems.

Effect of tillers on corn yield: Exploring trait plasticity potential in unpredictable environments

AbstractLong‐term selection in maize (Zea mays L.) favored single‐stalked phenotypes limiting vegetative growth. However, reduced plant densities create conducive environments to the expression of vegetative branches called tillers. Tiller expression has motivated discussions about its yield effect in variable environments, but tiller research is lacking for modern corn genotypes. The objectives of this study were to (a) quantify the relative importance of management, environment, and interactions on the yield effect of tiller expression for two modern genotypes; (b) understand effects of observed tiller density, plant density, and their interaction on yield; and (c) identify key environmental determinants of yield response to tiller density in modern genotypes. In 10 environmentally diverse site‐years across Kansas, tiller presence and removal were evaluated in two commercial corn hybrids (P0657AM and P0805AM) across three target plant density levels (25,000, 42,000, and 60,000 plants ha−1). Yields were increased or unaffected by greater plant densities and tiller presence within site‐years. Environments varied in yield responsiveness to tiller density, but fine‐tuning plant density was needed to maximize yields. Sites with yields most responsive to tiller density were characterized by good soil properties and photothermal quotient values (e.g., soils with high organic matter and climates with greater solar radiation and cooler temperatures). Favorable growing conditions can be exploited by plasticity traits such as tillering in unpredictable environments with annually variable optimum plant densities while limiting potential yield loss and producer risk due to disproportionate plant density.

Nitrogen deficiency and corn yield with delayed N application

AbstractDelaying the application of N to corn (Zea mays L.) may help to match N supply to N uptake, but may also increase the risk of yield loss if N is applied too late or N uptake is delayed. In a 3‐yr study with corn following soybean [Glycine max (L.) Merr.] (SC) and corn following corn (CC), N application was either split, with half (112 kg N ha–1) at planting and the rest at stages ranging from V3 to R3; or with the entire increment (224 kg N ha–1) applied at these stages. In SC, there was no yield loss from delaying application of the second increment of N to as late as R3, but yields declined as the full increment of N was delayed, by 5% at V9 to 34% at R3. In CC, delaying the second N increment to stage R2 or R3 lowered yield by 5% compared to application at V3, and delaying the full increment of N increasingly lowered yield, by 8% at V6 to 40% at R3. Corn able to recover leaf chlorophyll content (SPAD) following delayed N application produced full yields, and cumulative N deficiency (CND, ΔSPAD × delay expressed as modified growing degree days over periods with ΔSPAD>0, SPAD‐MGGD) was linearly correlated with yield loss. With half of the N at planting, the remainder could be delayed to R1 or later without yield loss, but without N at planting, N needed to be applied before stage V9 in SC and before stage V6 in CC in order to assure maximum yield.

Opportunities and risks with early sowing of sunflower in a salt-affected coastal region of the Ganges Delta

On low-lying land in the Ganges Delta, waterlogging, salinity, and poor soil structure are constraints to intensifying cropping systems. Early sowing of dry season (rabi) crops in this area is hypothesized to increase yield potential because the current late sowing exposes the crop to less favourable temperature conditions, soil dryness, and salinity stresses. Field experiments were conducted over 2 years to identify the opportunities and challenges of early sowing between mid-November and mid-December for maximizing sunflower yield in Southern Bangladesh. Sunflower was dibbled into untilled wet soil on five occasions (23 and 30 November and 10, 20, and 30 December in 2016–2017 and 25 November, 14 and 25 December, and 10 and 25 January in 2017–2018), with two mulching treatments (rice straw at ~ 5 t ha−1 and 15–20% rice residue retention). Sowing before 15 December was associated with larger heads, more seeds per head, greater seed weight, and higher grain yield (3.5–4 t ha−1) in the first year, but early sowing was also risky since, in the second year, the sunflower sown on 25 November was hampered by heavy rainfall, which depressed yield compared to crops sown on 15 December. Increased yield from early sowing before 15 December was associated with higher soil water, lower soil salinity, and higher solute potential compared to sowing after 15 December. Lower yield in late sown crops was also associated with increased temperature at grain-filling stage. The rice straw mulch significantly improved soil water availability, reduced soil salinity, increased soil solute potential, and increased yield in the second year. In this paper, we show for the first time that sunflower sown before 15 December in the Ganges Delta has higher yield potential, but to gain the benefits of the earliest sowing, growers will need to manage the increased risk of yield loss due to waterlogging.

Poppy (Papaver somniferum L.) Intercropping with Spring Barley and with White Clover: Benefits and Competitive Effects

Poppy seed production is susceptible to abiotic and biotic stress and weed infestation, which introduces the risk of total crop failure. For the purpose of risk minimization, poppy was grown in additive intercropping systems with early and late sown white clover and spring barley sown at three different densities in a three year field trial to assess their roles in poppy cropping while adding ecological benefits to the crop rotation. Poppy yielded between 798.7 and 1293.1 kg ha−1, with no significant yield effects of intercropping with white clover, compared to poppy sole-cropping. Dry matter, height, leaf area index and C/N ratio of the poppy plants were not significantly impacted by the clover intercrop either, independent on its sowing date. Higher poppy yields (695.6–918.8 kg ha−1) and LERs (1.11–1.84) in the poppy–barley intercrop were achieved in 2018 and 2020 compared to 2019 (≤361.5 kg ha−1, LER ≤ 0.99), mainly due to differences in seeding dates, precipitation and nutrient availability. Therefore, previous seeding of poppy limits competition when intercropped with barley while white clover and poppy can be sown at the same time. The effect of barley seeding densities on the intercrop performance was small as was the influence of intercropping on weed cover, number and biomass. The weed regulating effect needs to be further examined, however, we conclude that intercropping of poppy is a promising strategy for its cultivation, in terms of minimizing the risk of total yield losses when precisely managed.

Risk Analysis of Wheat Yield Losses at the County Level in Mainland China

There have been few pieces of research focused on quantifying wheat yield loss risk based on high-resolution long-term historical data. What is more, the existence of the area scale effect reduces the certainty and spatial comparability of results. In this study, long-term wheat yield and planting area data at the county level from 1981 to 2010 were used. The spatial distribution of wheat yield loss risks was analyzed in the mainland of the People’s Republic of China (China for short). An improved comprehensive risk index of yield loss risk was established by integrating the reduction rate, coefficient of variation, and the probability of occurrence for different yield reduction rates after removing the effect of area scale. 874 main wheat-growing counties in the mainland of China were divided into lowest, lower, moderate, higher, and highest risk areas based on it. The high-risk areas are located in Yellow-Huai-Hai Plain, including Shandong, Henan, northern Anhui, and parts of Jiangsu Province.

Brown Stink Bug (Hemiptera: Pentatomidae) Damage to Seedling Corn and Impact on Grain Yield.

Brown stink bugs, Euschistus servus, are an important early-season pest of field corn in the southeastern United States. Feeding in the early stages of corn development can lead to a number of growth deformities and deficiencies and, ultimately, a reduction in yield. An observational and two experimentally manipulated trials were conducted in 2017 and 2018 to 1) determine optimal timing for assessing brown stink bug damage, 2) assess the level of damage from which yield compensation can occur, and 3) examine the relationship between brown stink bug density and early-season damage and yield. Fields were identified with infestations of brown stink bugs and a damage rating system for early stages of corn was established. Varying rates of brown stink bug densities were introduced using field cages and damage was assessed throughout the season. The density and duration of stink bug infestations were critical factors for damage potential, with each day of active feeding per plant resulting in a loss of ~14 kg/ha in yield. The level of damage in early stages of corn was categorized into easily identifiable groups, with only the most severe damage leading to a reduction in yield. Moderate and minimal feeding damage did not result in yield loss. This study emphasizes the need for early and frequent scouting of corn to determine the risk of damage and yield loss from brown stink bugs. Results from this study can be used to help develop management programs for brown stink bugs in the early vegetative stages of field corn.