Increasing drought stress due to climate warming has triggered various negative impacts on plantations in dryland areas, including growth reduction, crown dieback, and even tree mortality, with unavoidable consequences for forest ecosystems. However, how drought stress progressively led to the damage process from growth reduction to mortality for mature trees remains largely unclear, especially its varying soil moisture thresholds. Here we selected mature trees in larch (Larix principis-rupprechtii) plantations in the dryland areas of northwest China, and monitored the progressive tree responses in an extreme summer drought event in 2021, including transpiration, radial growth, leaf area index, discoloration, defoliation, crown dieback and tree mortality. The results showed strong responses of larch trees to summer drought, such as large stem shrinkage, dramatic decrease in transpiration and leaf area index, and obvious discoloration, defoliation, crown dieback and tree mortality at some sites. The intensity of tree responses mainly depended on soil moisture rather than meteorological factors and there were strong relationships between tree responses and relative soil water content (RSW) of 0-60 cm layers. Based on the trees responded to RSW, five soil drought stress levels or progressive mortality stages and their corresponding RSW thresholds were determined as following: no detectable hydraulic limitations (RSW>0.7, Level I), persistent stem shrinkage and onset of transpiration reduction (0.45<= 0.7, Level II), onset of slight discoloration and defoliation (0.35<= 0.45, Level III), onset of crown dieback and tree mortality (0.25<= 0.35, Level IV), and severe defoliation, crown dieback and tree mortality (RSW <= 0.25, Level V). This study showed that the trees responded to climatic drought were strongly regulated by soil moisture and thus were strongly site-specific. These findings will help to evaluate the degree and spatio-temporal distribution of tree damage and mortality in plantations under increasing climatic drought, particularly in dryland areas.

Wireworms (Coleoptera: Elateridae), the larval stage of several economic click beetle species, have become major cereal crop pests in key agricultural regions of Canada and the United States. In recent trials following minimum tillage practices (Alberta), we determined that isocycloseram, the initial isoxazoline agricultural seed treatment developed, provided exceptional control of cereal crop damage, and significantly reduced neonate and resident wireworm populations of the sugarbeet wireworm, Limonius californicus (Mannerheim). Herein we evaluated isocycloseram in cultivated wheat plots (British Columbia) for control of the dusky wireworm, Agriotes obscurus L., and collectively these studies determined that isocycloseram applied at 5.0 to 7.5 g AI/100 kg seed protected crop stand and yield from these species equal to all currently registered wireworm seed-treatment insecticides (ie, neonicotinoids, diamides, and meta-diamides), and significantly reduced resident and neonate wireworms equal to levels expected from the former industry standard lindane. Abiotic and biotic conditions negatively influencing insecticide performance and ways to mitigate them were also identified. These conditions include soil fertility, moisture, and compaction, and planting after most wireworm feeding in the spring has occurred.

Sugar maple, an economically and ecologically important tree in the northern hardwood forest, has experienced regeneration failure that in the Northeast portion of the range has been variously attributed to soil acidification and resultant changes in soil chemistry, impacts of climate change, and effects of species composition. In a 5-year study spanning a latitudinal gradient in the state of New Hampshire, we examined evidence for these three hypotheses to explain sugar maple regeneration patterns. Overall, sugar maple seedling survival was highest in the two sites with lower sugar maple abundance. Alternatively, the two other sites with greater than 50% sugar maple relative dominance shared the following outcomes: higher seed production per area, greater foliar pest damage, lower seedling survival, lower sapling density, and higher canopy maple mortality, while the sites with lower dominance of maple had opposite outcomes. Based on field data and a common garden experiment, conspecific impacts on seedling survival were related to foliar pests and fungal pathogens rather than through soil feedbacks. These results lend support to other studies encouraging promotion of stand tree diversity and avoidance of monocultures.

Greece's olive oil production is significantly affected by the olive fruit fly Bactrocera oleae (Diptera: Tephritidae), and its presence is perceived when it is too late to act for damage recovery. In this work, some unexplored entomopathogenic fungi (EPFs) were studied for their efficacy on olive fruit fly pupae in soil samples. Olive grove soil samples were collected to evaluate the effect of EPFs in their natural environment. The parameters that were analyzed to evaluate the performance of EPFs on B. oleae included the adult survival time, pupa hatch time, and the presence of mycelium on B. oleae pupae and dead adults. The efficacy of some EPFs was highlighted by the mycelium present on dead B. oleae adults after treating pupae with fungal isolates on the soil substrate. The results showed that for the soil substrate, external fungal growth was observed in dead adults with A. contaminans, A. keveii, A. flavus P. lilacinum, and T. annesophieae (100%). Remarkably, the lowest male proportion for soil and non-soil substrates was for A. flavus (0.41-0.42) for the first time, for A. keveii (0.36), and for P. citreosulfuratum (0.41) on the soil-only substrate in contrast to the control treatment (0.5 for both substrates). Given the high infestation caused by the olive fruit flies in Greece, the results of the study emphasize to use of incorporating certain EPF-based biopesticides into integrated pest management (IPM) programs.

Winter extreme low temperature events have been occurring frequently both before and after the winter season. The freezing resistance temperature of wheat is far lower than the intensity of low temperatures during the mid-winter period. Therefore, it is necessary to further quantify and evaluate the impact of low-temperature periods and durations during the early winter and the green-up period on the freezing resistance of wheat, based on different evaluation indicators. Through conducting experiments in an artificial low-temperature control chamber, this study investigates the critical temperature thresholds for the impact of different low-temperature periods and durations on the tiller and yield of winter wheat, as well as the critical temperature thresholds for soil effective negative accumulated temperature. The results demonstrate that (1) the tiller mortality rate (RT) and yield reduction rate (RY) of winter wheat during the winter increase with the severity and duration of low temperatures, showing an S-shaped curve. The winter wheat mortality rate during the early winter is related to the soil effective negative accumulated temperature in an exponential function, while the mid-winter and green-up stages have a linear relationship. (2) The freezing threshold temperatures for the RT, RY and soil negative accumulated temperature (SENAT) in different low-temperature periods (early winter, mid-winter, and green-up periods) range from - 11.7 to -17.9 degrees C, -9.4 to -15.6 degrees C, and 15.9 to 131.7 degrees Ch (2.2 to 16.8 degrees Cd), respectively. (3) The freezing threshold temperatures for the RT and RY in different low-temperature durations (1 day, 2 days, and 3 days) range from - 2.8 to -17.9 degrees C and - 9.4 to -15.6 degrees C, respectively. The findings of this study provide technical support and scientific guidance for the global cultivation structure and variety layout of winter wheat under the background of climate warming, as well as for the prevention and reduction of freezing damage and yield losses.

Dry season droughts may increasingly threaten Mediterranean forests under climate change. While plants employ three desiccation avoidance strategies to avoid or delay dehydration damage, including reduced water loss, enhanced tissue water storage, and improved root water access, resource allocation competition may lead to trade-offs among these strategies that are not yet fully understood. We investigated six Mediterranean woody species by analysing: (1) twig hydraulic capacitance (0.32 - 2.81 mmol m(-2) MPa-1) representing tissue water storage capacity; (2) twig residual conductance (g(res)) at 25 degrees C (1.23 -7.73 mmol m(-2) s(-1)) reflecting water loss rate; and predawn water potential (Psi(PD)) and its difference from midday water potential (triangle Psi) at the end of the dry season as root water access indicators. Significant trade-offs in plant desiccation avoidance strategies were observed as g(res) positively correlated with triangle Psi (R-2 = 0.78, P = 0.02) and twig hydraulic capacitance negatively correlated with Psi(PD) (R-2 = 0.68, P = 0.04). Consequently, species with greater root water access exhibited lower tissue water storage capacity and higher g(res), potentially increasing mortality risk when soil moisture becames limiting. By inverting a plant desiccation model, we also demonstrated that minimum survival-required hydraulic capacitance and a novel risk index were both positively correlated with Psi(PD), consistent with historical mortality records. Additionally, despite temperature-dependent g(res) patterns which revealed species-specific responses, elevated temperatures amplified the risk index for all species.

Due to the increasing frequency of extreme weather events, drought damage to trees threatens forestry production and forest ecosystems worldwide. Assessing the site conditions under which trees are vulnerable to drought damage provides key information for the establishment of countermeasures to prevent such damage. This study aimed to clarify the differences in drought vulnerability of young planted forests between regions and species by using forest insurance claims from all over Japan as a damage indicator. We targeted the two most damaged species in two of the most drought-affected regions from 2016 to 2021. Although landform and soil type were found to be influential factors in the Kamikawa Subprefecture of Hokkaido, these factors did not affect the drought damage in Yamaguchi Prefecture. In Kamikawa, the drought damage risk was high for Larix kaempferi on river terraces and for Abies sachalinensis on mountain areas with compacted brown forest soil. Clayey soil, which can prevent plants from absorbing water, has been known to distribute on the terraces and the mountains with compacted soil in Kamikawa. Therefore, our analysis identified clayey soil as a cause of drought vulnerability in Kamikawa. In addition, L. kaempferi was suggested to be especially vulnerable on flat terraces with less permeable clayey soil due to root damage associated with excessive soil moisture before drought. This study demonstrated that forest insurance can be used not only for damage compensation, but also as a source of information for identifying region- and species-specific risk factors for meteorological damage in forests.

Increased tree mortality rates have been observed worldwide in connection to climate warming-related processes, such as drought, heat, fire, and insect pest outbreaks. An understanding of the drivers of tree mortality during the Anthropocene is urgently needed to estimate forest vulnerability in a warmer climate. In this study, we assessed the drivers of tree mortality in an urban recreational boreal forest area in Helsinki, Finland, of approximately 830 ha, where increased tree mortality rates have been recently observed. A time series of aerial images was used to quantify tree mortality over the area to detect dead trees from 2005 to 2021 at seven timestamps. In total, 6008 dead trees were observed from the aerial images collected during the monitoring period. Forest environmental and climatic variables were used to explore the tree mortality drivers for individual trees and tree communities using logistic regression and correlation analysis. Our results showed that droughtrelated variables, i.e., the standardised precipitation evapotranspiration index and the Palmer drought severity index, were linked with increased tree mortality rates. We found that the stand-level basal area predicted tree mortality risk and was linked to site type; smaller basal area stands were located on rocky dry soils, resulting in a greater probability of tree mortality. We also observed that trees at high elevations or on steep slopes showed a greater mortality risk. Our results can increase the understanding of tree mortality in urban areas and help the planning of built and green areas in a changing climate.

Invasive pests cause major ecological and economic damages to forests around the world including reduced carbon sequestration and biodiversity and loss of forest revenue. In this study, we used Random Forest to model forest mortality resulting from a 2015-2017 Spongy moth outbreak in the temperate deciduous forests of Rhode Island (northeastern U.S.). Mortality was modeled with a 100 m spatial resolution based on Landsat-derived defoliation maps and geospatial data representing soil characteristics, drought condition, and forest characteristics as well as proximity to coast, development, and water. Random Forest was used to model forest mortality with two classes (low/high) and three classes (low/med/high). The best models had overall accuracies of 82% and 65% for the two-class and three-class models, respectively. The most important predictors of forest mortality were defoliation, distance to coast, and canopy cover. Model performance improved only slightly with the inclusion of more than three variables. The models classified 35% of forests as having canopy mortality >5 trees/ha and 21% of Rhode Island forests having mortality >11 trees/ha. The study shows the benefit of Random Forest models that use both defoliation maps and geospatial environmental data for classifying forest mortality caused by Spongy moth.

Maize ranks as the 3rd most economically valuable cereal crop worldwide but its productivity is under severe threat by an invasive pest, Spodoptera frugiperda (Lepidoptera: Noctuidae). The 3rd instar S. frugiperda larvae are most damaging stage of lifecycle, that's why the present study is planned to evaluate the impacts of silicon dioxide (SiO2), potassium silicate (K2SiO3), and sodium silicate (Na2SiO3) @ 400 and 800 ppm against the 3rd instar larvae of S. frugiperda by using two application methods (soil drenching and foliar spray). Moreover, the impact of Si supplementation on biological parameters (pupation, adult emergence, and egg laying) was also recorded. The findings showed that SiO2 application through foliar spray @ 800 ppm concentration caused maximum mortality (12-36%) followed by K2SiO3 (8-32%) and Na2SiO3 (4-24%). The soil drenching method of silicon application was less effective in comparison to foliar spray. The surviving larvae showed negative impacts on growth and development, including pupation (48, 52, and 60%), adult emergence (41.67, 46.15, and 53.33%) and fecundity (46.20, 52.60, and 54.20) by SiO2, K2SiO3 and Na2SiO3 foliar spray @ 800 ppm respectively. The present study revealed that Si had a significant detrimental impact on immature stages of S. frugiperda. Consequently, Si treatment can reduce S. frugiperda reproduction which may ultimately decrease S. frugiperda establishment and early harm in maize. Silicon applications may offer a sustainable way to lessen S. frugiperda infestations, improving maize protection and lowering the need for conventional insecticides.