Reduce Pesticide Use Research Articles

Removing non‐crop flowers within orchards promotes the decline of pollinators, not their conservation: A comment on McDougall et al. (2021)

Abstract Abundant and diverse floral resources are needed for the preservation of pollinator populations and the services they provide to human societies. However, pollinators are negatively affected by several agricultural practices, among which pesticide use and ‘weed’ removal stand out. McDougall et al. (2021) published a paper titled ‘Managing orchard groundcover to reduce pollinator foraging post‐bloom’, where they propose removing the within‐field flowering ground vegetation after the mass flowering period of the crop ends, to reduce pesticide exposure. They consider this is a bee conservation strategy, after observing it reduces the abundance and diversity of pollinators within the crop. However, despite assuming this implied a realisation of an expected reduction in pesticide exposure, this was not quantified. Here, we give three main arguments against the proposal of the authors, that is, the need for providing accessible, sufficient, safe and seasonally‐spread feeding resources to crop pollinators, the potential role of diverse floral resources in their pesticide tolerance, and the urgent need to reduce pesticide use and impact in agriculture.

Differentiating the effects of organic management, pesticide reduction, and landscape diversification for arthropod conservation in viticulture

Biodiversity loss is a main challenge for agricultural sustainability. Major drivers include local management and landscape simplification. Therefore, conservation measures aim to increase organic agriculture, reduce pesticide use, and increase the proportion of semi-natural habitats (SNH). Yet, it is important to understand the effects of such measures. We investigate how arthropod biomass, taxa richness, and community composition in Malaise trap samples are affected by organic management, pesticide use, and SNH in the landscape. The 32 studied vineyards were chosen in a crossed design of management (organic vs. conventional) and pesticide use (regular vs. reduced) along a gradient of landscape composition. Pesticide reduction by 55% was obtained by including half of the vineyards with fungus-resistant grape (FRG) varieties. Malaise trap samples were weighed and arthropods identified using metabarcoding. Surprisingly, biomass was almost one-third higher in conventionally managed vineyards compared to organic ones. Taxa richness increased by more than one third when the proportion of SNH in a radius of 1,000 m in the surrounding landscape increased from zero to 50%. Diptera richness tended to be 4% higher in conventionally managed vineyards and the richness of Hymenoptera was 9% higher in FRG varieties. Community composition changed with the proportion of SNH and differed between organic and conventional management. Overall, organic viticulture was not effective to enhance the arthropod community, which was dominated by flying insects in our study. Agricultural policies should therefore rather preserve and promote SNH in the surrounding in order to promote arthropod biodiversity in viticultural landscapes.

Consumers' Preferences for Apple Production Attributes: Results of a Choice Experiment.

Various food safety and environmental problems in China have raised consumer awareness of food safety issues and negative environmental impacts in various supply chains. This research assessed consumer preferences and willingness to pay (WTP) for food safety and ecosystem delivery attributes associated with apples, demonstrated through the application of different traceability systems. Research participants were recruited in Beijing (N = 384) and Shanghai (N = 320). Choice experiment methodology was applied. The data were analyzed using conditional logit, random parameter logit, and latent class models; the results indicated significant consumer preferences for traceability information, including in relation to lower pesticide usage and application of organic fertilizer during primary production. The results also indicated that participants in this research had a significant willingness-to-pay premium for apple products that had production information traceability, had reduced pesticide use, and were grown with organic fertilizers. The models demonstrated heterogeneous preferences among participants such that consumers could be divided into three classes: non-price-sensitive (53.5%), pesticide-sensitive (21.7%), and price-sensitive (24.8%).

Consumer identity but not food availability affects carabid diet in cereal crops

Understanding trophic interactions in agroecosystems is crucial for harnessing ecosystem services such as pest control, thus enabling a reduction in pesticide use. Carabid beetles (Coleoptera: Carabidae) have the potential to regulate not only insect pests but also weed seeds and slugs. The aim of this study was to investigate the food choice of different carabid species in the experimental setting of a cereal field with varying seed and slug prey availability during the season. In addition to varying food availability, the effects of species identity and season on carabid food choice should also be closely examined. Therefore, the gut contents of 1,120 beetles of eight carabid species were screened for the DNA of plants, aphids, springtails, earthworms and slugs via diagnostic multiplex PCR and a nested metabarcoding approach for plant species identification. Plant DNA was detected far more often (72%) than the various animal prey types (less than 12.5% each). Within the plant detections, 80 weed species were identified in the metabarcoding, with Galinsoga parviflora/quadriradiata (Galinsoga spp.—quickweeds) as the most frequently detected species. Carabid food choice was driven by their species identity and seasonality, while no effect of increased availability of seeds and slugs on their food choice was detected. While weed seeds seem to be an important food source for carabids, their availability does not directly affect the carabid diet. The importance of consumer identity and seasonality highlight the need for a diverse carabid species community for resilient pest control services.

Coacervate-Enhanced Deposition of Sprayed Pesticide on Hydrophobic/Superhydrophobic Abaxial Leaf Surfaces.

Deposition of high-speed droplets on inverted surfaces is important to many fundamental scientific principles and technological applications. For example, in pesticide spraying to target pests and diseases emerging on abaxial side of leaves, the downward rebound and gravity of the droplets make the deposition exceedingly difficult on hydrophobic/superhydrophobic leaf underside, causing serious pesticide waste and environmental pollution. Here, a series of bile salt/cationic surfactant coacervates are developed to attain efficient deposition on the inverted surfaces of diverse hydrophobic/superhydrophobic characteristics. The coacervates have abundant nanoscale hydrophilic/hydrophobic domains and intrinsic network-like microstructures, which endow them with efficient encapsulation of various solutes and strong adhesion to surface micro/nanostructures. Thus, the coacervates with low viscosity achieve high-efficient deposition on superhydrophobic abaxial-side of tomato leaves and inverted artificial surfaces with a water contact angle from 170° to 124°, much better than that of commercial agricultural adjuvants. Intriguingly, the compactness of network-like structures dominantly controls adhesion force and deposition efficiency, and the most crowded one leads to the most efficient deposition. The tunable coacervates can help comprehensively understand the complex dynamic deposition, and provide innovative carriers for depositing sprayed pesticides on abaxial and adaxial sides of leaves, thereby potentially reducing pesticide use and promoting sustainable agriculture.

Oenological potential of wines produced from disease-resistant grape cultivars.

Within the EU, changes in policy and public sentiment have made it more urgent to consider the adoption of sustainable agricultural practices. Consequently, one of the EU's goals is to reduce pesticide use by 50 per cent by 2030, including in viticulture. One of the proposed approaches is to expand the use of disease resistant hybrid grape-cultivars (DRHGC), such as 'PIWI' grapes (German, Pilzwiderstandsfähige Rebsorten), and to introduce new DRHGCs. However, the characteristics of DRHGCs are different from those of Vitis vinifera, which makes it necessary to take measures and make changes in winemaking technology to maintain high wine quality. This paper examines the chemistry of wines made from DRHGC and discusses their impact on aroma and flavor profiles. It also reviews the main winemaking practices suggested to produce high-quality wines from DRHGCs. The chemistry of DRHGCs is different to wine produced from V. vinifera, which can lead to both challenges during winemaking and unusual flavor profiles. Although newer DRHGCs have been bred to avoid unexpected flavors, many DRHGCs are still rich in proteins and polysaccharides. This can make tannin extraction difficult and produce wines with little astringency. In addition to this, new or alternative winemaking techniques such as thermovinification and the use of alternative yeast strains (non-Saccharomyces) can be used to produce wines from DRHGCs that are acceptable to consumers.

Drip fertigation with straw incorporation promotes soil microbial network complexity and potentially reduces pathogen abundance in greenhouse vegetable production systems

Continuous monoculture, conventional flood fertigation and low soil fertility increase the risk of soil-borne diseases in greenhouse vegetable production systems. Drip fertigation with straw incorporation (DIF+S) significantly improves resource use efficiency and reduces environmental risks compared to conventional fertigation. However, it remains unclear whether DIF+S positively affects soil microbial diversity and community structure and reduces the occurrence of soil-borne diseases. Therefore, a two-factor field trial was conducted in a greenhouse tomato production system with drip vs. flood fertigation, with and without straw incorporation across the seven growing seasons. The experimental treatments were as follows: (i) conventional flood irrigation with overfertilization (CIF); (ii) CIF + straw incorporation; (iii) drip fertigation with reduced irrigation and fertilization (DIF); and (iv) DIF + straw incorporation. Across the seven growing seasons, the average water and nitrogen use efficiency (WUE and NUE) was two- and threefold higher for DIF than for CIF, respectively, whereas tomato yields remained high. DIF significantly increased soil bacterial diversity and network complexity compared to CIF but had no effect on the soil fungal community. DIF significantly reduced the relative abundance of Fusarium-induced tomato wilt. Moreover, straw application significantly decreased fungal diversity while increasing fungal network complexity, although no effect on the bacterial community was found. The relative abundance of plant pathogens, such as Cladosporium, Fusarium and Alternaria, which are related to soil-borne diseases of tomato plants, was significantly reduced when straw was incorporated. Our results highlight that drip fertigation combined with straw incorporation significantly positively affects soil microbial diversity and stability. Thus, DIF+S is a sustainable and effective technology for maintaining soil health and reducing pesticide use in greenhouse vegetable production systems.

Impact of operation scale and labor costs on pesticide use intensity of fruit farmers: evidence from peach farmers in China

The impact of the operation scale on the pesticide use intensity of farmers may be related to different crop types and production factors constraints over different operation scales. This study uses the survey data of 522 peach farmers in China in 2018 to investigate the impact of the operation scale on pesticide use intensity and discusses the influence of labor costs constraint on the pesticide use intensity of different operation scales of cash crop. Empirical analysis results reveal that the operation scale shows a U-shaped relationship with pesticide use intensity; as the labor costs of pesticide use increases, the pesticide use intensity decreases. After classifying peach farmers into large-scale and small-scale farmers, significant differences were found between them. Large-scale farmers are more inclined to use pesticides scientifically because of the dual constraints of pesticide costs and labor costs, while small-scale farmers are more inclined to overuse pesticides because of a lower constraint of labor costs. Further, as labor costs of pesticide use rise, the negative influence of scale expansion on pesticide use intensity decreases. Therefore, the formulation and implementation of relevant policies need to distinguish different crop types and different operation scales and need to understand the actual needs and constraints of farmers, so as to truly reduce pesticide use intensity and increase pesticide use efficiency.

Avian regulation of crop and forest pests, a meta-analysis.

Birds have been shown to reduce pest effects on various ecosystem types. This study aimed to synthesize the effect of birds on pest abundance, product damage and yield in agricultural and forest systems in different environments. Our hypothesis is that birds are effective pest regulators that contribute to a reduction in pest abundance, enhancement of yield quality and quantity and economic profit, and that pest regulation may depend on moderators such as the type of ecosystem, climate, pest, and indicator (ecological or economic). We performed a systematic literature review of experimental and observational studies related to biological control in the presence and absence of regulatory birds. We retained 449 observations from 104 primary studies that were evaluated through qualitative and quantitative analyses. Of the 79 studies with known effects of birds on pest regulation, nearly half of the 334 observations showed positive effects (49%), 46% showed neutral effects, and very few (5%) showed negative effects. Overall effect sizes were positive (mean Hedges' d=0.38 ± 0.06). A multiple model selection retained only ecosystem and indicator types as significant moderators. Our results support our hypothesis that there is a positive effect of avian control of pests for each analyzed moderator and this effect was significant for both ecological and economic indicators. Avian regulation of pests is a potential effective approach for environmentally friendly pest management that can reduce pesticide use regardless of the context of implementation. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Abundance, perceptions and utilizations of termite mounds in Cambodia

AbstractIn the Lower Mekong Basin, paddy fields often appear as mosaics, with soil mounds covered by trees or other plants in a spotty distribution. These soil mounds are commonly named termite ‘lenticular mounds’ because termite bioturbation is considered to be at their origin. Termite mounds host a large diversity of animals and plants, increasing landscape patchiness. Because the preservation of these islands of biodiversity is threatened by modern agricultural practices, the aim of this study was to quantify their abundance and the services they provide to the local population. The abundance of mounds and their use by the population were quantified in a catchment in Cambodia. We found that mounds density reached ~2 mounds ha−1. Interviews carried out within the catchment showed that most of the interviewees used mounds for increasing the fertility of their field and for the cultivation of rice and other plants (e.g. sponge gourd and pumpkin). In addition to their potential to increase plant productivity, the survey revealed that animals (rats and snakes), mushrooms and 13 plant species found on or in mounds were consumed by the population. In addition to potentially contributing to an increase in food diversity, mounds also impacted farmers' health by allowing access to 20 medicinal plant species and indirectly via a reduction in pesticide use. In conclusion, this study is the first attempt to quantify the large number of services provided by termite mounds in Cambodia. This increase in the knowledge of the diversity of environmental and socioeconomic services provided by termite mounds is likely to contribute to their preservation and provide a basis for the sustainable management of biodiversity in paddy fields in the Lower Mekong Basin region.

Important role of the government in reducing pesticide use and risk sustainably in Thailand: Current situation and recommendations.

Agriculture is an important aspect of Thailand's GDP and development. It ranks as the 8th largest exporter in the world, however, pesticide use associated with the agriculture is ranked 18th in the world and 5th in Asia. Previous studies have clearly stated that pesticides are a threat to human health and the environment. The government is now making efforts to address pesticide use and the health impacts of pesticide use, however, these efforts are still in need of completion. This paper aims to summarize: (1) the current situation with regard to pesticide use in Thailand; (2) the current situation with regard to pesticide poisoning in Thailand; and (3) important role of government in reducing pesticide use and risk sustainably in Thailand: current situation and recommendations. This article suggests that government is a significant driver for reducing pesticide use and risk sustainably and the establishment of push and pull policies, legislation, and strategies. The government needs to strictly adhere to international conventions. Introducing a pesticide tax is essential to reduce redundant pesticide use. Updating of the current act, specific regulations with regard to pesticides and strict enforcement are urgently required. Licensing pesticide applicators should be implemented continuously. Promotion of alternative pest management is needed by supportive production inputs, technology, and markets as well as the development of a monitoring and certification system. Educating consumers on how to choose safe agricultural products and reduce risk from pesticide residues in the products is also necessary. All approaches should be implemented simultaneously and instantly. Importantly, the government needs to cooperate with agricultural sectors, health and environmental sectors, private sectors, as well as food industries to tackle complicate issues in a sustainable manner and lower pesticide use and risk sustainably in Thailand.

Nature benefit hypothesis: Direct experiences of nature predict self‐reported pro‐biodiversity behaviors

AbstractHuman activities are damaging the world's ecosystems, posing a serious threat to life on Earth, including humanity. To address this situation, widespread and significant changes in human behavior are necessary. Direct experiences of nature can encourage individuals to adopt positive actions towards biodiversity (hereafter pro‐biodiversity behavior), but this relationship has not been well studied. Using a large sample of Japanese adults, we demonstrate that both recent and childhood frequencies of nature experiences are associated with an increased likelihood of exhibiting pro‐biodiversity behaviors. This association was found to be consistent across various forms of behaviors, including purchasing ecofriendly products, reducing pesticide use in domestic gardens, and donating to conservation organizations. However, our research also reveals a declining trend of childhood experiences of nature in Japan, resulting in an “extinction of experience.” Our results suggest that enhancing people's personal experiences with nature could help promote desired behavioral change to halt biodiversity loss.

Potential to reduce pesticides in intensive apple production through management practices could be challenged by climatic extremes

Apples are the third most produced fruit in the world, but their production is often pesticide-intensive. Our objective was to identify options for pesticide reduction using farmer records from 2549 commercial apple fields in Austria during five years between 2010 and 2016. Using generalized additive mixed modeling, we examined how pesticide use was related to farm management, apple varieties, and meteorological parameters, and how it affected yields and toxicity to honeybees. Apple fields received 29.5 ± 8.6 (mean ± SD) pesticide applications per season at a rate of 56.7 ± 22.7 kg ha−1, which included a total of 228 pesticide products with 80 active ingredients. Over the years, fungicides accounted for 71 % of the pesticide amounts applied, insecticides for 15 %, and herbicides for 8 %. The most frequently used fungicides were sulfur (52 %), followed by captan (16 %) and dithianon (11 %). Of insecticides, paraffin oil (75 %) and chlorpyrifos/chlorpyrifos-methyl (6 % combined) were most frequently used. Among herbicides, glyphosate (54 %), CPA (20 %) and pendimethalin (12 %) were most often used. Pesticide use increased with increasing frequency of tillage and fertilization, increasing field size, increasing spring temperatures, and drier summer conditions. Pesticide use decreased with increasing number of summer days with maximum temperatures >30 °C and number of warm, humid days. Apple yields were significantly positively related to the number of heat days, warm humid nights, and pesticide treatment frequency, but were not affected by frequency of fertilization and tillage. Honeybee toxicity was not related to insecticide use. Pesticide use and yield were significantly related to apple varieties. Our analysis shows that pesticide use in the apple farms studied can be reduced by less fertilization and tillage, partly because yields were >50 % higher than the European average. However, weather extremes related to climate change, such as drier summers, could challenge plans to reduce pesticide use.

Acute Pesticide Poisoning in Tobacco Farming, According to Different Criteria

Brazil is one of the world's largest pesticide consumers, but information on pesticide poisoning among workers is scarce. To evaluate acute pesticide poisoning among tobacco growers, according to different criteria. This was a two-step cross-sectional study with 492 pesticide applicators. It used a 25 question pesticide-related symptoms (PRS) questionnaire and medical diagnosis for comparison with toxicological assessment. Associations were evaluated using Poisson regression. 10.6% reported two or more PRS, while 8.1% reported three or more. Furthermore, 12.2% received a medical diagnosis of poisoning. According to toxicologists, possible cases accounted for 14.2% and probable cases for 4.3%. PRS increased during the period of greater exposure. Those exposed to dithiocarbamates, sulfentrazone, pyrethroids, fipronil and iprodione exhibited more PRS. The number of exposure types, multi-chemical exposure, clothes wet with pesticides and spillage on the body/clothes were associated with acute poisonings. All criteria showed sensitivity greater than 79% for probable cases but only greater than 70% for medical diagnosis when compared to possible cases, presenting substantial Kappa agreement. The prevalence of acute pesticide poisoning is much higher than officially recorded. Trained physicians can screen for pesticide poisoning. It is necessary to improve workers' education to reduce pesticide use and exposure to them.

Herbicide Use in the Era of Farm to Fork: Strengths, Weaknesses, and Future Implications.

Climate change mitigation is a major concern of the European Union (EU). In 2019, the EU presented the European Green Deal (EGD), a new environmental strategy that aimed to neutralize climate change by 2050. Within its policy areas, the EGD included the Farm to Fork (F2F) Strategy that aims to reduce pesticide use by 50%, by 2030. This reduction was proposed due to the supposed negative effects of pesticides on the environment and its biota. Among the different pesticide groups (herbicides, fungicides, insecticides, etc.) though, herbicides are perhaps the hardest to reduce. This review aimed to shed light to any factors that might hinder the reduction of herbicide use; thus, the implementation of the Farm to Fork Strategy underlines some of its weaknesses and highlights key points of a viable herbicide reduction-related policy framework. The literature suggests that integrated weed management (IWM) consists perhaps the most suitable approach for the reduction of herbicides in the EU. Even though it is too soon to conclusively assess F2F, its success is not impossible.

Width of vegetated buffer strips to protect aquatic life from pesticide effects

Vegetated buffer strips (VBS) are an effective measure to retain pesticide inputs during rain events. Numerous studies have examined the retention effects of VBS on pesticides. However, no study has addressed on a large scale with event-related peak concentrations how wide the VBS should be to avoid ecological impacts on aquatic life. Here, we investigated for 115 lowland stream sections in Germany the relevance of environmental and physico-chemical parameters to determine the in-stream pesticide concentration and their ecological risks. Based on peak concentrations related to rain events with precipitation amount resulting in VBS relevant surface runoff for 30 of the 115 investigated stream sections (25 to 70 mm/d), we demonstrated that the average width of VBS was the main parameter (R² = 0.38) reducing the pesticide input ratio, indicating a relevant proportion of surface runoff contributing to the total in-stream pesticide concentrations. Additionally, dry ditches within agricultural fields increased pesticide input (R² = 0.31). Generally, substances classified as slightly mobile were better retained by VBS than mobile substances. Other factors including slope, land use and vegetation cover of VBS had only a minor influence. We assessed the ecological risk of in-stream pesticide concentrations by quantifying exceedances of regulatory- (RAC) and field-validated acceptable concentrations (ACfield). We then translated this ecological risk into protective VBS width by calculating the quotient of in-stream concentration and threshold (RQ). We estimate that a VBS width of 18 m is sufficient to meet the RQACfield protection goal for 95% of streams. The presence of dry ditches increased the protective VBS width to 32 m. In current agricultural practice, however, 26% of the water stretches investigated do not comply with the prescribed 5 m VBS. An extension of the VBS area to 18 m would demand 3.8% of agricultural land within the catchments. A 50% reduction in pesticide use, as required by the European green deal, would still result in 39% (RAC) and 68% (ACfield) of event-related samples being exceeded. Consequently, we see the extension of the VBS width as the most efficient mearsure to sustainably reduce pesticide concentrations in small streams.

Impact of Chlorpyrifos on Cytopathological Indices in Mangrove Crab, Episesarma tetragonum (Fabricius).

Chlorpyrifos is an organophosphate insecticide occurring in aquatic ecosystems. Due to exposure to xenobiotics, several harmful effects on aquatic organisms are noticed worldwide. Mangrove crabs are an ecologically important aquatic invertebrate species in food web interactions and in the mangrove ecosystem. Therefore, this study aimed to evaluate the cytotoxic effects of chlorpyrifos on the mangrove crab, Episesarma tetragonum. Crabs were exposed to 0.0294 and 0.0588 ppm of chlorpyrifos for 7 and 28 days. Cytopathologic effects on the gill, hepatopancreas, and muscle were investigated, and observations were compared with a control group. The results suggest that chlorpyrifos induces time- and concentration-dependent cytopathological alternations in the gill and exhibited epithelial lifting, oedema, necrosis, and a fusion of secondary lamellae and haemorrhage. The deceased hepatopancreas showed infiltration, a large lumen formation, and the disappearance of haemocytes, while the muscle tissue showed atrophy, necrosis, a wavy appearance, an accumulation of granular material between muscle fibres, and fragmentation in a mangrove crab. This study shows the great potential of cytopathological investigations, allows us to assess the sensitivity of various aquatic animal species to potentially dangerous compounds, and calculates safe concentrations with which to reduce pesticide use.

Organic Walnut Cultivation in Intensive and Super-Intensive System—Sustainable Investment. Case Study: Gorj County, Romania

The interest of the countries with traditions of walnut cultivation to increase the quantity and quality of walnut production is due to the fact that the organic cultivation of walnut is a sustainable business, with an ecological, economic and social impact. The walnut plant (Juglans regia) is a resource for food, dermatocosmetic and phytotherapeutic products, is raw material in the wood industry and a source of biomass. It is a species suitable for organic farming, with no chemical factors input (in line with the EU program to reduce pesticide use and fuel consumption by 35% in the context of the current energy crisis), and has properties of atmosphere purification and air-conditioning. Due to the creation of varieties with high production potential, suitable for cultivation in intensive and super-intensive plantations and also due to the government financial support, walnut plantations can contribute to the development of new valorization directions for the obtained production, by processing fruits and other vegetative organs (green nuts, green and dried shells, foliage, timber) with significant profits. In order to establish and capitalize on a walnut plantation in the pedological and climatic conditions of Romania, pedological studies, worthiness and pedoclimatic studies were carried out in the depression area of Gorj County and show the stages of cultivation technology in intensive and super-intensive systems. The sustainability and economic efficiency of setting up organic walnut cultivation has been highlighted in view of the costs for agrotechnical works, labor and material expenses. According to the analysis of the efficiency indicators, it has been shown that the establishment of an ecological walnut orchard, on an area of 1 ha, in Gorj County, Romania, is a sustainable, appropriate and opportune investment, in terms of capitalizing on the agricultural potential of the land, environmental protection and with social and economic impact.

Pest prevention, risk, and risk management: The case of Drosophila suzukii

AbstractPest prevention can play an important role in reducing pest pressure and pesticide use. Yet its adoption remains suboptimal. We develop a theoretical model to analyze the circumstances that favor or hinder the uptake of preventive measures against pests, and test the derived hypotheses using an empirical application of Swiss grapevine producers' decisions on preventive measures against Drosophila suzukii. We show that higher risk aversion hinders farmers' prevention efforts. Furthermore, lower general background risk, characterized by the use of crop insurance, decreases pest prevention. We discuss the implications for supporting policy goals of managing pest pressure and reducing pesticide use.

Pedigree-based analysis in multi-parental diploid rose populations reveals QTLs for cercospora leaf spot disease resistance.

Cercospora leaf spot (CLS) (Cercospora rosicola) is a major fungal disease of roses (Rosa sp.) in the southeastern U.S. Developing CLS-resistant cultivars offers a potential solution to reduce pesticide use. Yet, no work has been performed on CLS resistance. This study aimed to identify QTLs and to characterize alleles for resistance to CLS. The study used pedigree-based QTL analysis to dissect the genetic basis of CLS resistance using two multi-parental diploid rose populations (TX2WOB and TX2WSE) evaluated across five years in two Texas locations. A total 38 QTLs were identified across both populations and distributed over all linkage groups. Three QTLs on LG3, LG4, and LG6 were consistently mapped over multiple environments. The LG3 QTL was mapped in a region between 18.9 and 27.8 Mbp on the Rosa chinensis genome assembly. This QTL explained 13 to 25% of phenotypic variance. The LG4 QTL detected in the TX2WOB population spanned a 35.2 to 39.7 Mbp region with phenotypic variance explained (PVE) up to 48%. The LG6 QTL detected in the TX2WSE population was localized to 17.9 to 33.6 Mbp interval with PVE up to 36%. Also, this study found multiple degrees of favorable allele effects (q-allele) associated with decreasing CLS at major loci. Ancestors 'OB', 'Violette', and PP-M4-4 were sources of resistance q-alleles. These results will aid breeders in parental selection to develop CLS-resistant rose cultivars. Ultimately, high throughput DNA tests that target major loci for CLS could be developed for routine use in a DNA-informed breeding program.