Search Results (607)

Modulating the vine source–sink relationship is a proposed strategy to mitigate the detrimental effect of climate change frequently induced by elevated temperatures and water deficit conditions. In this regard, apical leaf removal could represent a reliable technique, even though its effects on grapevines subjected to different irrigation regimes are unexplored. This study aimed to clarify the effects of apical leaf removal applied before the onset of veraison (ELR) and during berry ripening (LLR, 16 °Brix) on grapevine physiology in vines subjected to full irrigation and water deficit conditions. The irrigation regimes prominently affected the vine physiological parameters over the leaf removal treatments. Both ELR and LLR vines showed transient increases in stem water potential only after the leaf removal. Consistently, the vine transpiration rate was similar between the leaf removal treatments, and even higher water consumption was measured in ELR well-watered vines, associated with new lateral growth. Significant increases in leaf gas-exchange parameters following ELR and LLR were observed only on the measurement dates immediately after the treatment application. However, both ELR and LLR vines consistently exhibited higher daytime net photosynthetic rates than the control, particularly in the afternoon and in the later stages of the season. These conditions led to a significant increase in the leaf total soluble solid concentration in LLR vines subjected to water deficit, which was also associated with a high carbon export rate. Our findings suggest that although apical leaf removal has a limiting effect on reducing the impact of water deficit on vine physiology, it can be an effective agronomic strategy to boost leaf carbon fixation and exportation, particularly when applied during ripening. Full article

Peptidoglycan recognition proteins (PGRPs) are conserved pattern recognition receptors (PRRs) that play key roles in insect innate immunity by binding bacterial peptidoglycan (PGN) and activating downstream signaling pathways. The Dendrolimus kikuchii, a major defoliator of coniferous forests in southern China, has incompletely characterized immune defenses. This study systematically identified the PGRP gene family in D. kikuchii based on genome-wide data, identifying 10 PGRP genes with typical PGRP/Amidase_2 conserved domains, including 6 PGRP-S proteins and 4 PGRP-L proteins. Additionally, to further investigate the evolutionary relationships of these PGRP genes, a maximum likelihood (ML) phylogenetic tree was constructed using PGRP amino acid sequences from 6 different insect species, along with the 10 PGRP amino acid sequences from D. kikuchii. Phylogenetic analysis revealed that the DkikPGRP genes of D. kikuchii are distributed across distinct evolutionary branches and share high homology with PGRP genes from other insects, suggesting a close evolutionary relationship between the PGRP genes of D. kikuchii and those of other insect species. Transcriptome profiling revealed that DkikPGRP-S1, -S2, -S3, -S4, and -S5 were upregulated in the midgut, fat body, and hemolymph after Bt infection, showing tissue- and time-specific immune responses. Functional assays using siRNA knockdown demonstrated distinct roles of DkikPGRP-S4 and DkikPGRP-S5: DkikPGRP-S5 mainly promoted antimicrobial peptide (AMP) expression, including attacin, lebocin, lysozyme, and cecropin, whereas DkikPGRP-S4 showed a complex regulatory pattern, enhancing lebocin and lysozyme but suppressing attacin without affecting gloverin or cecropin. Silencing either gene significantly increased larval mortality upon Bt challenge. These results highlight the specialized immune regulatory functions of PGRPs in D. kikuchii, provide new insights into host–pathogen interactions, and suggest potential molecular targets for sustainable pest management strategies. Full article

Ascotis selenaria has recently shifted hosts to become a major defoliator in Southern China’s eucalyptus plantations. To facilitate Integrated Pest Management (IPM), we investigated the genetic origins, life history, and reproductive bio-ecology of this population. Mitochondrial COI analysis revealed that the Southern China population aligns phylogenetically with South Asian clades, distinct from Northern China populations. Life table analysis confirmed six larval instars, with the final instar exhibiting exponential consumption, accounting for 79.68% of total food intake. Reproductive assays demonstrated significant protandry and a novel bimodal ovarian maturation rhythm (peaking on days 3 and 7). Crucially, female fecundity declined sharply after a 3-day mating delay, and mating with older males severely reduced egg hatchability in older females. These findings suggest that control thresholds must shift from visual damage assessment to monitoring early-instar larvae (1st–3rd instars). Furthermore, the combination of protandry and reproductive sensitivity implies that mating disruption strategies must be deployed prior to male emergence. This study provides the biological basis for a dual-window IPM framework targeting this emerging pest. Full article

The Colorado potato beetle (CPB) is the primary defoliator of potatoes and is notorious for its ability to develop resistance to various insecticides. This remarkable adaptability may partly reflect selective pressures imposed due to the beetle’s coevolution with toxic Solanaceous host plants. As the initial interface between the environment and the insect olfactory system, odorant-binding proteins (OBPs) may sequester excess harmful molecules, such as insecticides and plant allelochemicals, in the perireceptor space, mitigating deleterious effects on vulnerable olfactory sensory neuronal dendrites. In this study, we identified an antenna-specific OBP (LdecOBP33) that is significantly upregulated in a pesticide resistant strain compared to a susceptible one. Competitive displacement fluorescence binding assays demonstrated that the LdecOBP33 protein exhibited broad affinity toward a range of plant volatiles and insecticides. Silencing LdecOBP33 decreased the beetle’s resistance to imidacloprid and impaired its ability to locate host plants. Together, these findings provide insight into a key molecular factor involved in the CPB’s response to environmental challenges, suggesting a potential link between insects’ adaptation to xenobiotics and their olfactory processing. Full article

This study presents a near-real-time water stress monitoring framework for tropical heterogeneous landscapes by integrating optical and radar remote sensing data within the Google Earth Engine platform. Five complementary indices, vertical transmit/vertical receive–vertical transmit/horizontal receive (VV/VH) ratio, Dual Polarimetric Radar Vegetation Index (DpRVI), Normalized Difference Water Index (NDWI), Normalized Difference Moisture Index (NDMI), and Ratio Drought Index (RDI), were analyzed across three contrasting agricultural systems: paddy, sugarcane, and rubber, revealing distinct phenological and water stress dynamics. Radar-derived structural indices captured patterns of biomass accumulation and canopy development, with VV/VH values ranging from 4.2 to 12.3 in paddy and 5.4 to 6.0 in rubber. In parallel, optical moisture indices detected crop physiological stress; for instance, NDMI dropped from 0.26 to 0.06 during drought in sugarcane. Cross-index analyses demonstrated strong complementarity; synchronized VV/VH and RDI peaks characterized paddy inundation, whereas lagged NDMI–VV/VH responses captured stress-induced defoliation in rubber trees. Temporal profiling established crop-specific diagnostic signatures, with DpRVI peaking at 0.75 in paddy, gradual RDI decline in sugarcane, and NDMI values of 0.2–0.3 in rubber. The framework provides spatially explicit, temporally continuous, and cost-effective monitoring to support irrigation, drought early warning, and agricultural planning. Multi-year validation and field-based calibration are recommended for operational implementation. Full article

This paper describes a study conducted to investigate the spread of Lecanosticta acicola, the cause of brown spot needle blight (BSNB), in Pinus mugo dune forests in the Polish Baltic region. Between 2023 and 2025, 22 sites were surveyed, including coastal forests and some ornamental plantings. Characteristic BSNB symptoms were recorded in 21 of the 22 locations, and the pathogen’s presence was confirmed through culture isolation and species-specific PCRs. The disease was most severe in compact, monospecific P. mugo thickets, where defoliation exceeded 30%, while mixed stands with P. sylvestris or occasionally P. nigra exhibited lower infection rates. A degree of infection of P. sylvestris was observed in proximity to heavily infected P. mugo stands, confirming interspecific transmission under high inoculum pressure. We observed nearly ubiquitous occurrence of L. acicola along the coast, suggesting an advanced stage of establishment. However, the very recent detection of the pathogen at the westernmost sites indicates ongoing westward spread. These findings highlight the vulnerability of coastal P. mugo populations and underline the need for genetic diversity data that would allow us to trace the origins and pathways of L. acicola spread in the south-eastern Baltic region. The potential adaptation of the pathogen to P. sylvestris in the future would pose a serious risk for Polish forestry. Full article

Cold winter injury is a significant challenge in cultivating tropical trees in temperate regions. The conventional solution involves heating the entire greenhouse to protect the plants; however, this approach is fuel-intensive and costly. This study investigated whether root-zone heating can mitigate cold injury in coffee trees. In the Control, non-heated treatments, leaf relative water content dropped to approximately 70%, leading to wilting, whereas in the Heat treatment, it remained above 90%. In the Control treatment, defoliation progressed, ultimately resulting in more than 50% leaf loss. In contrast, defoliation was reduced by approximately 20% with the Heat treatment. During the cold-treatment period, photosynthesis declined sharply in both the Control and Heat treatments, with CO₂ assimilation dropping to nearly zero. However, one week after the complete of cold treatment, F_v/F_m recovered to pre-treatment levels, while CO₂ assimilation and electron transport rates improved to more than 50% of pre-treatment levels in the Heat treatment. These findings indicate that root-zone heating helps prevent leaf wilting and defoliation by maintaining high leaf water content. The surviving leaves recovered their photosynthetic function and were crucial in subsequent biomass production. Thus, root-zone heating is a cost-effective and efficient strategy for cultivating tropical trees in temperate regions. Full article

Long-term monitoring of tree crown condition is essential for assessing forest resilience under increasing climatic variability. This study presents a comprehensive evaluation of oak (Quercus spp.) defoliation trends in Poland from 2015 to 2024, based on national forest health monitoring data. Mean defoliation remained relatively stable until 2018, followed by a significant increase in 2019 (+5.1 percentage points; p < 0.001), coinciding with a major drought event across Central Europe. In subsequent years, defoliation gradually decreased and stabilised, indicating partial canopy recovery. Segmented regression and spline models revealed a consistent breakpoint in 2019 across all age classes, with the most severe crown damage recorded in stands older than 100 years. Younger stands showed lower defoliation levels and higher regenerative capacity. A nonlinear relationship between defoliation and growing-season precipitation was also identified, showing that when rainfall fell below 40 mm, canopy loss exceeded 30%. The results confirm that oak defoliation reflects both short-term climatic stress and long-term structural changes. Integrating monitoring data with climatic analyses and statistical modelling improves the detection of stress-related drivers and the assessment of recovery processes. The combined use of these approaches supports adaptive forest management strategies, including the promotion of mixed-species and multi-aged stands, improvement of soil nutrient conditions, and targeted monitoring of drought-sensitive age classes, thereby enhancing the resilience of oak ecosystems to climate change. Full article

This study evaluated the effects of late pruning and late apical leaf removal on grapevine phenology, fruit composition, yield parameters, xylem sap carbohydrate content, and grape skin polyphenol levels over two consecutive vintages (2022 and 2023). As expected, delayed pruning shifted the phenological stages, with more pronounced delays observed in 2022 than in 2023. However, by August, all the treatments had reached the berry-softening stage, indicating a convergence in ripening. The grape juice composition showed no significant differences in sugar content in 2022; however, in 2023, the °Brix was notably reduced in control vines subjected to late apical defoliation. The titratable acidity and pH remained stable across treatments and years, while the malic acid concentrations were consistently higher in the late-pruned treatments, particularly LP2 (late pruning 2 was performed when the control vines had reached the eight-leaves-folded development stage). Late pruning significantly reduced the yield and bunch size, especially for the 2023 LP2 treatment. In contrast, late apical defoliation had minimal impact on the yield components. Vegetative growth, as assessed by cane diameter and weight, also declined under late pruning. Despite this, the xylem sap analysis revealed no significant changes in the glucose, fructose, or myo-inositol levels, suggesting that the carbohydrate reserves remained unaffected. Notably, LP2 consistently resulted in the highest total polyphenol content in the grape skins across both years, indicating enhanced phenolic maturity. Although the polyphenol concentrations were generally higher in 2023, the treatment effects varied more widely, likely due to the differing environmental conditions. These findings suggest that late pruning—particularly LP2—can be a valuable tool for improving grape phenolic quality, albeit at the cost of reduced yield and vine vigor. This study highlights the importance of site- and season-specific canopy management strategies in balancing fruit quality with productivity under variable climatic conditions. Full article

Forest damage has been increasingly recorded over the past decade in both Europe and Hungary, primarily due to prolonged droughts, causing a decline in forest health. In the framework of ICP Forests, the forest damage has been monitored for decades; however, it is labour-intensive and time-consuming. Satellite-based remote sensing offers a rapid and efficient method for assessing large-scale damage events, combining the ground-based ICP Forests datasets. This study utilised cloud computing and Sentinel-2 satellite imagery to monitor forest health and detect anomalies. Standardised NDVI (Z NDVI) maps were produced for the period from 2017 to 2023 to identify disturbances in the forest. The research focused on seven active ICP Forests Level II and 78 Level I plots in Hungary. Z NDVI values were divided into five categories based on damage severity, and there was agreement between Level II field data and satellite imagery. In 2017, severe damage was caused by late frost and wind; however, the forest recovered by 2018. Another decline was observed in 2021 due to wind and in 2022 due to drought. Data from the ICP Forests Level I plots, which represent forest condition in Hungary, indicated that 80% of the monitored stands were damaged, with 30% suffering moderate damage and 15% experiencing severe damage. Z NDVI classifications aligned with the field data, showing widespread forest damage across the country. Full article

The Common European ash (Fraxinus excelsior L.) is one of the main species constituting the field protection forest belts in Northeastern Bulgaria. Studies conducted in shelterbelts in Dobrich and Balchik in July 2020 and in Tutrakan and Dulovo in June–July 2022 revealed severe dieback of ash. The observed symptoms included density thinning of the crowns, dieback of branches, presence of sunken necrotic cankers, and light green to yellow foliage and premature defoliation. Parts of the shelterbelts were completely destroyed with 100% tree mortality. To determine whether the invasive Hymenoscyphus fraxineus or other pathogens are present in the ash field protective forest belts in Northeastern Bulgaria, fungal isolation was undertaken. Samples were collected from four locations: Dobrich and Balchik in June 2020, and Tutrakan and Dulovo in June–July 2022. The morphology, temperature–growth rate relationships, and pathogenicity of the two pathogenic fungal species isolated in this study—Diplodia fraxini and Diplodia seriata—were examined. Morphological and physiological studies confirm the molecular identification of the obtained plant pathogens. The Diplodia fraxini isolates (Dobrich 3, Tutrakan 2, and Dulovo 4) showed mycelial growth between 5 °C and 35 °C, with minimal growth at 5 °C (0.20–0.27 mm/day) and an optimum growth rate of 3.9–4.5 mm/day at 20–25 °C. Growth declined sharply above 30 °C, ceasing entirely at 35 °C. In contrast, D. seriata (Dulovo 5) exhibited higher growth rates, showing limited growth above 5 °C (~1 mm/day), and maximum growth of approximately 8 mm/day at 25 °C. Growth in D. seriata remained moderate up to 35 °C and ceased near 40 °C, indicating a broader temperature tolerance and higher upper thermal limit than D. fraxini. The results from the pathogenicity tests show that D. fraxini can cause necrosis on ash—both on leaves and twigs—and is likely involved in the investigated ash decline cases. Further studies of the spread and epidemiology of D. fraxini are needed in order to establish its occurrence on the territory of Bulgaria. Full article

Phthonandria atrilineata, also known as the mulberry looper, is a major defoliator of mulberry trees. This feeding behavior directly affects the growth of the trees and reduces the quality and yield of mulberry leaves for its use in sericulture. Despite its importance the molecular basis of its resistance to insecticides remains poorly understood. Therefore, this study aimed to comprehensively characterize the cytochrome P450 monooxygenases (P450s) gene family in P. atrilineata and identify key effectors responsible for responses to diverse chemical stressors. We integrated genome-wide re-annotation, phylogenetic analysis, and comparative transcriptomics following exposure to five chemically distinct insecticides. We identified a high-confidence set of 70 P450 genes, dominated by the CYP6 and CYP4 families, whose expansion was driven by tandem gene duplication. Transcriptomic analysis revealed a powerful yet highly selective “elite-driven” response, wherein a small subset of P450s was strongly induced by multiple insecticides. Random Forest and Support Vector Machine (SVM) models converged with differential expression data to pinpoint a core trio of P450s as primary drivers of detoxification: two generalists, CYP6(09521) and CYP6(04876), responsive to all compounds, and one potent specialist, CYP4(04803), exhibiting massive induction to a specific subset of insecticides. Our findings uncover a complex, energy-efficient metabolic strategy in P. atrilineata and identify pivotal P450 genes for broad-spectrum detoxification. These genes represent high-priority targets for developing molecular diagnostic tools for resistance monitoring and informing scientifically guided insecticide rotation strategies. Full article

Drought is a major stressor affecting tree physiology and is expected to intensify under climate extremes. Stems, partly due to their photosynthetic capacity, tend to be more drought-resilient than leaves. This study aimed to assess stem photosynthetic and its impact on carbon balance in leafless stems under drought conditions. Severe drought caused a marked decline in stem and root water potential (Ψ) and reduced stem water vapor conductance (g_tw) by about 40%. Despite this, stems retained the capacity for active gas exchange: though with reduced stem CO₂ efflux (ECO₂) and enhanced CO₂ refixation, which increased from about 40% under control conditions to ~55%–60% after drought, accompanied by a twofold increase in intrinsic water use efficiency (iWUE). Chlorophyll a fluorescence and pigment analyses indicated that the integrity of photosystem II (PSII) was preserved under drought, supporting sustained corticular photosynthesis. Concentrations of chloride, malate, and citrate in the xylem sap did not change significantly under drought, indicating a high capacity of stems to maintain homeostasis. Stable isotope analyses revealed drought-induced shifts in δ¹³C, consistent with altered carbon allocation following leaf abscission. These results confirm that stem photosynthesis and CO₂ reassimilation contribute significantly to stem metabolic resilience, mitigating drought-induced carbon losses and helping to preserve plant survival. Full article

Chemical defoliation is an important management practice in cotton to facilitate mechanical harvesting and leaf removal and maintain lint quality. Recent advances in precision agriculture have enabled the development of autonomous robotic platforms with a targeted side-spraying system that can achieve good canopy penetration while preventing soil compaction and crop mechanical damage. A side-wise spraying system allows for application of defoliant at different canopy heights. However, information on the effects of staggered defoliation on cotton fiber quality is limited. Thus, field research was conducted to evaluate the effects of various staggered application timing intervals (15, 10, 8, 5, and 3 days) on fiber quality and compare them with standard over-the-top broadcast applications. Staggered defoliation affected fiber length, with significant differences observed for upper half mean length, fiber length based on weight, and upper quartile length. Fiber maturity was also influenced by staggered defoliation timing, with a 15-day interval resulting in the lowest micronaire and higher immature fiber content. The effects of staggered defoliation on other parameters, such as strength, uniformity, and trash characteristics, varied across locations. The findings highlight the potential of robotic systems for chemical spraying and emphasize the need for further research on more precise and targeted application of defoliants to improve fiber quality. Full article

The bioinsecticide Bacillus thuringiensis subsp. kurstaki (Btk) is applied over large areas to reduce defoliation caused by the spruce budworm, an insect which affects millions of hectares of coniferous forests every 30 to 40 years in eastern North America. The aim of our study was to determine whether, in addition to its direct lethal effects, aerial spraying of Btk had sublethal effects on spruce budworm populations and their parasitism. Four sites were sprayed with Btk and compared to four control sites in two regions, one where the outbreak had started three years earlier and the other where it had been going on for 10 years. Insects were collected to compare budworm pupal mass and parasitism at different stages (L₅, L₆ and pupae). Budworm pupae were significantly lighter in Btk-treated sites than in controls, and in the older population than in the younger one. However, pupae collected from Btk-treated sites had the same mass in both regions, suggesting a minimum pupal mass threshold, which may affect population dynamics. Larval parasitism was low, but pupal parasitism was high and strongly influenced by an interaction between Btk and region, with a higher parasitism observed in Btk-treated sites of the younger population than in those of the older population. A significant interaction was observed between Btk treatment and region on the proportion of larvae that failed to complete development, which was particularly high in Btk-treated sites of the older population. Our study confirms the effectiveness of Btk in controlling spruce budworm populations directly but also indirectly through sublethal effects on budworm development, capacity to complete development, pupal size and parasitism. To maximize control efficacy, the timing of Btk applications could vary according to the age of populations during the budworm outbreak cycle. Full article