Degree Days Research Articles

Phenological, growth, and yield responses of sweet corn to elevational air temperatures in the humid tropics

Temperature plays a determinant role in the rate of plant metabolic activities and, accordingly, dictates the plant's phenological stages, growth, and productivity. The objective of this study was to evaluate the phenological, growth, and ear yield behavior of ten sweet corn hybrids in response to elevational temperature changes in the humid tropics. Seeds of ten hybrids were grown in three elevations (coastland, midland, and highland). Results show that the hybrids belonged to the same maturity group with comparable accumulated growing degree days, but they varied in green ear yield, harvest index, and heat use efficiency. It was also found that higher elevations lead to longer plant growth and fewer growing degree-day requirements, resulting in increased in biomass accumulation for ear and overall vegetative growth but more efficient in the heat use. These findings will be useful as a guide for crop management scheduling, including fertilizers application, pest control, diseases control, and weed control, to maximize sweet corn yield at different elevations in the humid tropics.

Influence of carcass mass on decomposition rate: A medico‐legal entomology perspective

AbstractBody decomposition is influenced by various factors, including temperature, rainfall, body mass, and the activities of insects and carnivores in areas where carcasses are abandoned. However, the specific impact of carcass mass on the decomposition rate remains unclear. Therefore, this study aimed to compare the effects of carcass mass on decomposition rate with controlled domestic environmental conditions. Carcasses were categorized as small and large. Decomposition patterns were evaluated using a visual scatterplot to illustrate the relationship between total body scores and log accumulated degree days (ADD). To quantitatively compare decomposition rates, a linear regression model was employed to analyze differences between the two carcass groups. Regardless of carcass mass, a similar oviposition period for flies (Diptera) was observed, and the external appearance of the carcass remained relatively stable until 1.8 logADD, marking the emergence of maggots. However, decomposition dramatically accelerated after reaching 1.8 logADD, coinciding with maggots hatching from eggs and their commencement of scavenging. In contrast to larger ones, the hastened decomposition of small carcasses can be attributed to the relatively substantial volume of Diptera larvae within the small carcasses, expediting colonization and utilization. Therefore, carcass mass should factor into postmortem interval estimation based on the degree of body decomposition.

The impact of volcanism on Scandinavian climate and human societies during the Holocene: Insights into the Fimbulwinter eruptions (536/540 AD)

Recent paleoclimatic research has revealed that volcanic events around 536–540 AD caused severe, short-term global cooling. For this same period, archeological research from various regions evidences significant cultural transformation. However, there is still a lack of understanding of how human societies responded and adapted to extreme climate variability and new circumstances. This study focuses on the effects of the 536/540 AD volcanic event in four Scandinavian regions by exploring the shift in demographic and land use intensity before, during, and after this abrupt climate cooling. To achieve this, we performed climate simulations with and without volcanic eruptions using a dynamically downscaled climate model (iLOVECLIM) at a high resolution (0.25° or ~25 km). We integrated the findings with a comprehensive collection of radiocarbon dates from excavated archeological sites across various Scandinavian regions. Our Earth System Model simulates pronounced cooling (maximum ensemble mean −1.1°C), an abrupt reduction in precipitation, and a particularly acute drop in growing degree days (GDD0) after the volcanic event, which can be used to infer likely impacts on agricultural productivity. When compared to the archeological record, we see considerable regional diversity in the societal response to this sudden environmental event. As a result, this study provides a more comprehensive insight into the demographic chronology of Scandinavia and a deeper understanding of the land-use practices its societies depended on during the 536/540 AD event. Our results suggest that this abrupt climate anomaly amplified a social change already in progress.

Artificial Intelligence & Nature-Based Solutions in Agriculture: A BT Cotton Pest Management Case Study in India

Artificial intelligence (AI)-based pest management advisory, based on integrated pest management (IPM), provided to cotton farmers on smartphones, resulted in a reduction in pest attacks & up to 22% higher income in the 1 year 2020-21 in Ranebennur, Karnataka, and Wardha, Maharashtra states. However, no significant benefit was seen in a multi-state experiment in 2021-22 due to unusually high rainfall, resulting in lower pest attacks. The artificial intelligence was used in pest detection & counting insect numbers in the pheromone trap to decide if threshold numbers were reached for pesticide spraying decisions. This was 1-2 weeks in advance of mass pest emergence and could control it to reduce crop damage. It required manual trap checking by the farmers on a weekly basis, which many farmers disliked. Artificial intelligence coupled to remote sensing, GIS, and/or farm sensors can benefit the farmers by cutting costs, increasing yield, and enabling cleaner production. Lower environmental pollution and less risk to farmers and consumers are co-benefits of the AI-IPM package. However, mating disruption technology, a competitor, includes putting 4-6 pheromone traps per acre for the mass capture of moths. It is organic-compatible, and another competitor is the mechanical growing degree day (GDD)-based IPM advisory, such as that provided by the startup “Fasal.” These are unintelligent, mechanical, but very effective algorithms. Thus, a cautious, logical, and gradual approach is needed in promoting AI in agriculture, also keeping in mind its impact on labour displacement.

Using the Degree-Day Method to Analyze Central Heating Energy Consumption in Cities of Northern China

In the context of global population growth and energy scarcity, building energy consumption has become a critical issue with implications for the sustainable development of human society. Winter heating consumption constitutes a large portion of total energy used in buildings, especially in regions with cold climates. This paper employs the degree-day method to analyze the energy consumption of central heating in northern Chinese cities. The study sample consists of 60 target cities, including 30 located in severe cold regions and the remaining 30 in cold regions. By utilizing heating energy consumption and climate data from 2019, the relationships between heating intensity (kWh/m2) and heating degree days (HDDs) are established for the selected cities. Additionally, statistical analysis and model comparisons are conducted. The results show strong positive correlations between heating intensity and HDDs in both severe cold regions and cold regions, with the actual heating base temperatures for the two regions being 21 °C and 22.3 °C, respectively. Moreover, the deviation index of heating intensity is introduced to analyze the energy consumption characteristics of central heating in northern cities from three perspectives: city size, level of heating development, and geographical regions. The analysis suggests that cities with large population, strong economies, and high levels of development exhibit better energy-saving performance. Lastly, several improvement suggestions are proposed to address the potential problems related to energy conservation of central heating systems in cities of northern China.

Relative comparison of the benefits of wall envelope insulation materials in the South African energy zones, subject to the new national building energy efficiency standards

Introduction: South Africa is ranked among the 20 highest greenhouse gas (GHG) emitters worldwide, mainly due to its heavy reliance on coal for energy. The residential building industry can play a significant role towards the minimization of both GHG emissions and energy consumption. This research assesses the beneficial impacts of utilizing wall envelope insulation measures using five insulation materials, for a detached residential building, within the seven energy zones of South Africa in accordance with the South African National code for Building energy efficiency (SANS10400-XA).Methods: Lifecycle analysis (for 50 years), regression methods and sequential search techniques of building energy modelling were used to determine both the energy saving implications of adopting the insulation materials (at various levels of thickness), and their corresponding energy payback periods. The study area consisted of eight selected locations representing all the seven energy zones in South Africa (Welkom, Witbank, Thohoyandou, Cape Town, Pretoria, Ixopo, Sutherland, and Fraserburg).Results: Sutherland (zone 6), Cape Town (zone 4) and Fraserburg (zone 7) benefitted most from energy savings due to application of insulation measures. Witbank (Zone 2), Thohoyandou (zone 3) and Pretoria (zone 5) never benefitted from application of wall envelope insulation (in terms of energy savings). Cellulose and straw yielded the lowest payback periods. Generally, polyurethane yielded the highest net energy savings at lower insulation thickness levels, while cellulose was preferable at higher insulation thickness levels in Welkom (zone1) Cape Town (zone 4), Ixopo (zone 5H), Sutherland (zone 6) and Fraserburg (zone 7).Discussion: Lower optimal wall envelope insulation thicknesses (that maximized energy savings) appeared to correspond to locations with higher annual temperature ranges. Higher temperature ranges (hence, higher degree days) would ensure that more energy is saved in order to keep the indoor temperatures within the acceptable comfort limits, due to application of insulation. However, the selection of insulation material is also influenced by other factors such as resistance to insect and mould attack (which easily affect bio-insulation materials), fire retardancy, durability (which affects cellulose), sound proofing, structural strength, and resistance to water vapour.

Predicting Floral Bud Progression for Three Peach Cultivars

The prediction of floral bud progression in commercial peach cultivars promotes knowledge about the adaptability of cultivars to the climatic conditions in a specific location under a climatic variability context. Phenology is relevant to improving the scheduling of cultural practices in peach orchards. This research aimed to predict the floral bud progression of three peach cultivars: ‘Harvester’, ‘Red Globe’, and ‘Rubyprince’. Floral bud progression was assessed using one-year-old shoots collected from an orchard located at the Chilton Research and Extension Center, Alabama. Samples were evaluated under laboratory and growth chamber conditions. We recorded the flower developmental stages daily to identify the transition among stages. Daily temperature records were used to estimate the heat requirement in terms of Growing Degree Days (GDD). After dormancy release, samples needed between 23 to 39 and 37 to 42 days to reach the petal fall stage for season 1 and season 2, respectively. In terms of heat requirements, cultivars needed between 425.5 to 721.5 and 684.5 to 777 GDD to end flowering. A logistic curve was adjusted to describe the growth of the different floral stages over time. The results are key to supporting peach growers in crop management practices such as orchard establishment, irrigation, fertilization, freeze and frost protection, and pollination under climate variability scenarios.

Relative Comparison of Benefits of Floor Slab Insulation Methods, Using Polyiso and Extruded Polystyrene Materials in South Africa, Subject to the New National Building Energy Efficiency Standards

This article aims to assess the benefits of floor slab insulation measures using extruded polystyrene (XPS) and polyisocyanurate (also referred to as polyiso or PIR) insulation materials at various levels of insulation thicknesses for a detached residential building. An EnergyPlus simulation analysis was carried out within the seven energy zones (represented by eight locations) of South Africa in accordance with the South African national code for building energy efficiency (SANS10400-XA). The energy savings and payback periods related to the use of the insulation over a lifecycle period of 50 years were assessed. Cape Town (zone 4) behaved differently from other locations and hardly benefited from the application of floor slab insulation measures. Generally, polyiso (PIR) insulation performed better than XPS for vertical gap insulation, and lower insulation thicknesses required higher insulation depths to maximize energy savings. Similarly, lower insulation thicknesses (25 mm and 50 mm) required higher perimeter insulation widths to maximize energy savings for horizontal perimeter insulation, especially in Sutherland (zone 6) and Cape Town. The maximization of energy savings was also achieved at low insulation thickness for the full floor slab insulation method, except for Sutherland and Fraserburg (zone 7). The locations that benefitted most from the floor slab insulation methods were Pretoria (zone 5), Thohoyandou (zone 3), Sutherland (zone 6), Fraserburg (zone 7), Welkom (zone 1), Ixopo (zone 5H), Witbank (zone 2), and Cape Town (zone 4), in that order. Generally, higher net energy savings are achieved in areas with lower humidity levels and areas with greater annual sums of both cooling and heating degree days.

Alnus viridis: an encroaching species with valuable nutritional value reducing livestock greenhouse gas emissions

Alnus viridis is a shrub species that has been increasing in many European mountains over the past decades, leading to a loss of agricultural areas and several negative environmental impacts. Recently, targeted livestock management systems have been investigated to reduce its encroachment. This study aims to provide an exhaustive assessment of A. viridis leaf composition and its temporal variation across the grazing season. A. viridis leaves were collected throughout the summers of 2020 and 2021 in four encroached sites across the Swiss and Italian Alps, characterized by different pedo-climatic conditions. Based on the data collected by meteorological stations, the growing degree days (GDD) were calculated for each site and year. The leaf functional traits (i.e., Leaf Dry Matter Content – LDMC – and Specific Leaf Area – SLA), chemical composition (macro- and micro-elements and fibre content), phenolic content, in vitro organic matter digestibility (IVOMD), and related gas production (CO2 and CH4) were assessed. The LDMC significantly increased throughout the season, whereas the SLA decreased. All macro- and micro-elements significantly varied during the season, with leaf nitrogen (N) and phosphorus (P) decreasing. In contrast, leaf fibre contents significantly increased as the season advanced. There was a significant increase in condensed tannin content during the summer season. Finally, adding A. viridis leaves (20% of diet on a dry matter basis) to cattle diets significantly reduced IVOMD, methane produced per digested organic matter (CH4/dOM) and CO2/dOM, compared to a 100% hay diet. Moreover, CH4/dOM and CH4/CO2 ratio increased during the summer season. These results highlight the potential of A. viridis leaves as a valuable forage resource, especially at the beginning of the summer. Such information could be used to optimize grazing of robust livestock in A. viridis-encroached alpine pastures in order to reduce its invasion and minimize greenhouse gases production at the same time.

Environmental factors controlling soil warming and wetting during 2000–2020 in permafrost and non-permafrost regions across the Qinghai–Tibet Plateau

The Qinghai–Tibet Plateau (QTP) has experienced rapid environmental changes, including climate warming and wetting, since the 1980s. These environmental changes significantly impact the shallow soil hydrothermal conditions, which have key roles in land–atmosphere feedback and ecosystem functions. However, the spatial variations and responses of soil hydrothermal conditions to environmental changes over the QTP with permafrost (PF) and seasonal frost (SF) remain unclear. In this study, we investigated the spatial variations in soil temperature (ST) and soil moisture (SM) changes over the QTP from 2000 to 2020 using 99 in-situ sites with observations at 4 depths (i.e. 10, 40, 100 and 200 cm). The main environmental controlling factors were further identified using a calibrated statistical model. Results showed that significant (p < 0.05) soil warming occurred at multiple soil layers during 2000–2020 with a wide variation (i.e. 0.033–0.039 °C per year on average), whereas the warming rates at PF sites were two times greater than those at SF sites. In addition, the soil wetting rate was high over the SF region, whereas the soil wetting rate was low over the PF region. Aside from air temperature, changes in thawing degree days and solar radiation (Srad) contributed most to soil warming in the PF region, whereas changes in rainfall, Srad and evaporation (EVA) have been identified as the key factors in the SF region. As for soil wetting, changes in snowfall, freezing degree days and vegetation have noticeable nonlinear effects over the PF region, whereas changes in EVA, Srad and rainfall highlighted distinct linear and nonlinear effects in the SF region. These findings enhance our understanding of the hydrothermal impacts of future environmental changes over the QTP.

Nitrogen rate and harvesting time based on growing degree days influenced winter cereal rye morphological traits, forage yield, quality, and farm profit in poorly drained Alfisols

AbstractWinter cereal rye (Secale cereale L.) (WCR) is often double cropped with maize for silage (Zea mays L.) to increase farm forage supply and profit. Spring nitrogen (N) fertilization to WCR could influence its production and quality at different harvesting times. Therefore, two on‐farm trials were conducted in the 2019–2020 and 2020–2021 growing seasons to evaluate the effect of harvesting time (late‐March to end‐of‐April considering the growth stage) and spring N fertilization (0, 23, 47, and 71 kg N ha−1) on WCR morphology, forage yield, nutrient removal, quality, and farm profit. Only two N treatments (0 and 47 kg N ha−1) were evaluated for each harvesting time in trial 1. A quadratic model best explained an increase in WCR dry matter (DM) yield in response to growing degree days (GDD) accumulation (R2 = 0.81). An increase in GDD linearly decreased WCR relative forage quality (RFQ). Benchmarking RFQ at 150 for dairy milk production indicates WCR should be harvested at a GDD of 543, at which WCR plant height was 31.8 cm and DM yield was 0.77 Mg ha−1. This resulted in loss of profit in both study years compared to later harvesting dates at higher GDDs. Benchmarking RFQ at 125 for heifer production indicated that harvest should occur at a GDD of 668, at which the WCR was 71 cm tall, and its DM yield was 2.25 Mg ha−1. Nitrogen balances were negative at the N0 treatment (0 kg N ha−1), indicating a need for some N to maximize WCR yield. We found that a rate between 21 and 47 kg N ha−1 maximizes yields reflecting slightly positive balances, in which the highest profits occur. Our results suggest that the harvesting time can be predicted by GDD and should be adjusted for RFQ. We conclude that less than 47 kg N ha−1 N fertilizer is required for WCR production in soils with manure history and high soil organic matter (&gt;30 g kg−1).

Propagating speedups during quiescence escalate to the 2020–2021 surge of Sít’ Kusá, southeast Alaska

Abstract We use satellite image processing techniques to measure surface elevation and velocity changes on a temperate surging glacier, Sít’ Kusá, throughout its entire 2013–2021 surge cycle. We present detailed records of its dynamic changes during quiescence (2013–2019) and its surge progression (2020–2021). Throughout quiescence, we observe order-of-magnitude speedups that propagate down-glacier seasonally from the glacier's upper northern tributary, above a steep icefall, into the reservoir zone for the surging portion of the glacier. The speedups initiate in fall and gradually accelerate through winter until they peak in late spring, ~1 − 2 months after the onset of melt. Propagation distance of the speedups controls the distribution of mass accumulation in the reservoir zone prior to the surge. Furthermore, the intensity and propagation distance of each year's speedup is correlated with the positive degree day sum from the preceding melt season, suggesting that winter melt storage drives the seasonal speedups. We demonstrate that the speedups are kinematically similar to the 2020–2021 surge, differing mainly in that the surge propagates past the dynamic balance line at the lower limit of the reservoir zone, likely triggered by the exceedance of a tipping point in mass accumulation and basal enthalpy in the reservoir zone.

Learning to balance wheat G × E × M interactions in response to a changing climate—The case for ultra‐early planting systems

AbstractReported global reductions in cereal grain yields due to increased global average temperature combined with increasing global populations peaking near 2050 create an immediate need to increase cereal grain yield potential and reduce the yield gap between realized on‐farm grain yield and potential yield. The development of an ultra‐early planting system for spring wheat (Triticum aestivum L.) on the northern Great Plains can increase the resiliency of current growing systems to a changing climate. This was achieved through the development of a unique set of practices designed to successfully shift current wheat production systems to ultra‐early growing systems. Ultra‐early‐planted wheat‐growing systems on the northern Great Plains will provide immediate benefits to the adopting producer in the form of increased grain yield and increased grain yield stability relative to current practices. As global average temperatures warm, and atmospheric CO2 concentrations increase, the northern Great Plains region is in a unique position to potentially realize grain yield increases rather than temperature‐driven grain yield decreases. Shifting planting earlier and taking advantage of increased growing degree day accumulation and water use efficiencies while avoiding higher temperatures during sensitive physiological periods are tactics implemented in ultra‐early growing systems that will increase in importance and relevance in the next three decades as average daily temperatures increase.

Reproductive phenology of the Chesapeake Bay blue crab population in a changing climate

Global temperatures are rising across marine ecosystems in response to climate change. Marine and estuarine-dependent species including the blue crab, Callinectes sapidus, may adapt to warming temperatures phenologically, by shifting the seasonal timing of biological events, such as reproduction. In Chesapeake Bay, average water temperatures have risen by an average 0.02°C per year since the 1980s. Extension of the blue crab spawning season, through earlier onset and later conclusion, may augment annual brood production and alter the efficacy of management strategies. The duration of the potential spawning season from 1985 to 2019 was assessed using degree days, and the observed spawning season from 1995 to 2019 was assessed using the occurrence of ovigerous crabs from the Virginia Institute of Marine Science Trawl Survey in the James River and in the mainstem of lower Chesapeake Bay. Spawning degree days (SDD) and reproductive degree days (RDD) were defined using minimum temperatures of 19°C and 12°C, respectively. The mean duration of the potential spawning season increased by 25% in SDD and 10% in RDD between 1985 and 2019 in the James River and lower Chesapeake Bay, respectively. This progressive expansion of the potential spawning season was not, however, reflected in the observed spawning season. Rather, the onset, conclusion, and duration of the observed spawning season were variable over the time series. The observed month of onset was driven by RDD in spring, whereby spawning began earlier during warmer springs. The spawning conclusion date was driven by the onset of spawning, rather than Fall temperature, such that the duration of the observed spawning season and, therefore, annual brood production did not change over time. In Chesapeake Bay, the spawning stock is protected by a sanctuary that is closed to fishing from mid-May to mid-September during the putative spawning season. An earlier start to the spawning season during warmer springs, as seen in recent years, is expected to reduce the efficacy of the spawning sanctuary and intensify exploitation of the spawning stock, without enhancing brood production, thereby reducing reproductive output of the blue crab population in Chesapeake Bay.

Quantitative improvement of streamflow forecasting accuracy in the Atlantic zones of Canada based on hydro-meteorological signals: A multi-level advanced intelligent expert framework

Developing reliable streamflow forecasting models is critical for hydrological tasks such as improving water resource management, analyzing river patterns, and flood forecasting. In this research, for the first time, an emerging multi-level TOPSIS (technique for order preference by similarity to the ideal solution) -based hybridization comprised of the Boruta classification and regression tree (Boruta-CART) feature selection, multivariate variational mode decomposition (MVMD), and a hybrid Convolutional Neural Network (CNN) Bidirectional Gated Recurrent Unit (CNN-BiGRU) deep learning was adopted to multi-temporal (one and three days ahead) forecast the daily streamflow in the Rivers of Prince Edward Island, Canada. For this aim, in the first step, the Boruta-CART feature selection technique determines the most effective lagged components among all the antecedent two-day information (i.e., t-1 and t-2) of hydro-meteorological features (from 2015 to 2020), including the water level, mean air temperature, heat degree days, total precipitation, dew point temperature, and relative humidity in the Bear and Winter Rivers of Prince Edward Island, Canada. Afterwards, a multivariate variational mode decomposition (MVMD) decomposes the input time series to decrease the complexity and non-linearity of the non-stationary ones before feeding the deep learning (DL) models. Here, the CNN-GRU was employed as the primary DL model, along with the kernel extreme machine method (KELM), random variational function link (RVFL), and hybrid CNN bidirectional recurrent neural network (CNN-BiRNN) as the comparative models. A TOPSIS scheme applying several performance measures like the correlation coefficient (R), root mean square error (RMSE), and reliability was designed for the robustness assessment of the hybrid (MVM-CNN-BiGRU, MVM-CNN-BiRNN, MVM-RVFL, and MVM-KELM) and standalone models. The computational outcomes revealed that in the Bear River, the MVM-CNN-BiGRU, owing to its best forecasting performance (one day ahead: TOPSIS score 1, R = 0.960, RMSE = 0.098, and reliability = 65.082; three days ahead: TOPSIS score = 0.999, R = 0.924, and RMSE = 0.33) outperformed the other hybrid models, followed by the MVM-CNN-BiRNN, MVM-RVFL, and MVM-KELM, respectively. Moreover, in the Winter River, the MVM-CNN-BiGRU in terms of (one-day ahead: TOPSIS score = 0.890, R = 0.955, RMSE = 0.274, and reliability = 34.004; three-days ahead: TOPSIS score = 0.686, R = 0.924, and RMSE = 0.330) was superior to the other models. The provided expert system could be vital in the local flood decision-making process, in the absence of streamflow information as input modeling, during the flood seasons to reduce flood damage in residential areas.

Determination of optimum insulation thickness of building walls according to four main directions by accounting for solar radiation: A case study of Erzincan, Türkiye

Reducing heat transfer from the building will reduce the energy cost required to heat the building. Significant energy savings of 25 % to 50 % can be achieved when the appropriate thickness of thermal insulation is applied to the building walls. In this study, calculations were made to determine the optimum insulation thickness of some thermal insulation materials used to reduce the heat transfer from buildings in Erzincan, located in Türkiye's fourth climate zone. The optimum thickness of the thermal insulation to be applied to the external walls was determined using the heating degree day method, taking into account the effect of solar radiation according to the four main directions. Optimum insulation thicknesses and payback periods were calculated for combinations of two building materials (pumice and bricks), four fuels (fuel oil, LPG, natural gas, and coal), and three insulation materials (XPS, EPS, and Rock wool). The numbers of heating degree days were calculated as 2229 in the north, 1425 in the east and west, and 1118 in the south direction for the four main wall directions. The lowest optimum insulation thickness for these heating degree day values, which minimizes the total heating cost, was obtained for pumice/XPS/natural gas combination. The optimum insulation thicknesses for this combination were calculated as 0.037 m in the north, 0.025 m in the east and west, and 0.02 m in the south direction. The calculated payback periods for all combinations range from 0.9 to 4 years and the payback period of Pumice/XPS/Natural Gas combination is 4 years.

Biology of Apricot Bud Gall Mite, Acalitus phloeocoptes Determining the Emergence Time of the First Generation Using the Degree Day Model and Its Control

Nourpour, F., S. Aramideh, S. Mirfakhraie and H. Kamali. 2024. Biology of Apricot Bud Gall Mite, Acalitus phloeocoptes Determining the Emergence Time of the First Generation Using the Degree Day Model and Its Control. Arab Journal of Plant Protection, 42(3): 275-280. https://doi.org/10.22268/AJPP-001255 The plum bud gall mite, Acalitus phloeocopte Nalepa (Acari: Trombidiformes) is one of the important pests of plum trees. The biology and control of this mite during the 2021-2022 period was investigated. The results obtained showed that this mite had four generations a year and spends the winter as adult female mite. The estimated degree days (DD) for the emergence of 50% of wintering mites with two temperature thresholds of 6.2 and 5.8°C degrees were calculated as 68.50 and 88.00 DD in 2021 and 72.00 and 90.50 DD in 2022, respectively. The number of new galls formed by this mite following different treatments such as volck oil (as winter oil), liquid sulfur, propargit, phenpyroxymit, abamectin, tetradifon and sunmite along with water as a control treatment was determined. The results showed that in 2021, the sulfur treatment led to the least number of new galls 14.22±0.53, whereas in 2022 abamectin gave the least number of new galls 17.70±1.32. The integrated pest/crop management including pruning and removing infested branches in winter, a foliar spray with 80% liquid sulfur at the end of winter before budding or spraying with abamectin using degree-days following 50% overwintering mite emergence from galls, gave the best results and is recommended for adoption by farmers. Keywords: Biology, degree day, plum bud mite, control, acaricides.

Ensuring reliability: What is the optimal time for power plant maintenance in Texas as the climate changes?

We analyzed data for the Electric Reliability Council of Texas (ERCOT) to assess shoulder seasons – that is, the 45 days of lowest total energy use and peak demand in the spring and fall typically used for power plant maintenance – and whether their occurrence has changed over time. Over the period 1996–2022, the shoulder seasons never started earlier than late March nor later than mid-October, corresponding well with the minimum of total degree days. In the temperature record 1959–2022, the minimum in degree days in the spring moved earlier, from early March to early February, and in the fall moved later, from early to mid-November. Warming temperatures might cause these minima in degree days to merge into a single annual minimum in December or January by the mid‐2040s, a time when there is a non-trivial risk of 1-day record energy use and peak demand from winter storms.

Emergence timing of smallflower umbrella sedge (Cyperus difformis), barnyardgrass (Echinochloa crus-galli), and bearded sprangletop (Leptochloa fusca spp. fascicularis) in California water-seeded rice

Abstract Late-season weed emergence in California rice fields complicates decisions concerning the timing of control measures. The objective of this study was to predict the emergence of three problematic weed species in rice using thermal time models. Smallflower umbrella sedge, barnyardgrass, and bearded sprangletop seedlings were counted and removed daily at three locations across the Sacramento Valley rice-growing region in 2018. The accumulation of thermal time (growing degree days; GDD) commenced with the initial flooding of the fields at each location, utilizing the specific base temperatures corresponding to each species. The pattern of emergence as a function of GDD was modeled with a Weibull function. Root-mean-square values for comparing actual and model-predicted cumulative emergence values were 6% to 23%. Percent cumulative emergence initially increased rapidly for smallflower umbrella sedge and reached 90% emergence with accumulation of 13 GDD. Barnyardgrass emerged after smallflower umbrella sedge and reached 90% emergence with an accumulation of 124 GDD. Bearded sprangletop had a delay of 64 GDD compared to barnyardgrass to reach first emergence and reached 90% emergence at 215 GDD. The period of weed emergence at all field sites differed across the three species and led to a continuous spectrum of weed emergence over time. This study characterizes the emergence of three economically important rice weeds and provides useful information for the timing of weed management. Typical herbicide applications on the day of seeding may have less efficacy on the late-emerging weeds, causing reduced weed control. Delayed herbicide application, overlay of residual herbicides, or use of herbicides with longer residual activity are suggested to control late-emerging weeds.

Comparative analysis of growth cycles among three weedy Avena species: Insights from field observations.

Avena species, especially A. fatua, A. sterilis and A. ludoviciana, are among the most problematic weed species in many crops worldwide. The growth cycles of these three species could be helpful in understanding their growth cycle and their implications for agriculture and weed management. The growth cycles of these species were studied altogether or in combination with any single or double combinations of the other species in cereal fields in Türkiye, using two populations of each in a common garden experiment in Bornova district, Izmir, Türkiye. Germination and growth experiments were conducted in the laboratory and screen house, respectively. Various phenological parameters were recorded during the experiment and data were analyzed using R software. There were no significant differences in germination, emergence, SPAD values, leaf width, plant height, or plant dry weight among the species or populations. The SPAD values and width of the flag leaf and the leaf before the flag leaf were strongly correlated. Plant weight increased with increasing tiller number. The length of the ligule in a population of A. sterilis was significantly greater than that in populations of two other species, and it was concluded that the species is not A. fatua or A. ludoviciana if the length of the ligule is greater than 10 mm. The length of the spikelets of A. sterilis was greater than 65 mm with awn and greater than 35 mm without awn; these values were significantly greater than those of two other species that were shorter than 55 with awn for A. fatua and 30 mm without awn for A. ludoviciana, respectively. Avena ludoviciana had fewer tillers than the other two species. The plants emerged at 37.58 GDD at the soil surface temperature, which corresponds to 7 days after sowing. The growing cycles of the species differed: 196 days for A. sterilis, 201 days for A. fatua, and 209 days for A. ludoviciana after emergence, although there were no clear differences in earlier growth stages. This study provides initial basic information about the Avena spp., and it is concluded that even if a field has mixed Avena populations, herbicides can be applied simultaneously because the early development stages of the three species are very similar. In future prospects, there is a need for proper studies about the management of all Avena spp. on the basis of growth stages and growing degree days in regional context.