Prevalence and Severity of Citrus Decline and Its Management in Orchards of Panauti Municipality, Nepal

Prevalence and Severity of Citrus Decline and Its Management in Orchards of Panauti Municipality, Nepal | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article Prevalence and Severity of Citrus Decline and Its Management in Orchards of Panauti Municipality, Nepal Neelam Limbu, Ritu Raj Lamsal, Anupama Shrestha This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7250604/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Citrus Decline, a complex and devastating disorder caused by various biotic and abiotic factors has emerged as a significant challenge for citrus cultivation in Nepal. This study on “Prevalence and severity of citrus decline and its management practices in citrus orchards of Panauti municipality” was conducted in Panauti municipality of Kavre district of Nepal during the month of April/May - July/August, 2023 with the combination of survey and research. Survey was conducted with 30 respondents randomly and interviewed with questionnaire to extract data on comprehensive overview of citrus decline and its management practices, whereas research was conducted with 30 different leaves samples for disease isolation along with the determination of pH from the soil samples collected from the study site. The survey findings showed that the total number of 3213 citrus trees under 10 ha of land was done, with 98% of farmers facing citrus decline problem where disease incidence of 41% fungal, 34% parasitic, 5% bacterial, 15% viral and 5% others were observed and pest incidence with 34.48% leaf miner,28.74% fruit fly, 19.54% mites, 17.24% aphids were observed. Similarly in management practices, 86.66% of farmers were use farm yard manure but only 16.66% of them use recommended dose of manure and fertilizers, the training, pruning was performed by only 6.66% of farmers, 85% of farmers were seen intercropping the citrus orchards with pumpkin, cucumber, tomato etc. In the context of research, 30 leaves sample were isolated in different agar media with the positive result of powdery mildew in 20 leaves sample, sooty mold in 28 leaves samples and negative result in all leaves sample isolated suspecting of Citrus canker. Iodine scratch method for rapid detection of citrus greening disease was done and negative result in all leaves samples were obtained. Citrus decline stands as a significant constraint in citrus farming in Nepal, urging prior attention and the implementation of improved management practices to safeguard the sustainability and prosperity of the citrus industry. Horticulture Agricultural Engineering Citrus cultivation citrus disease isolation of disease management practices sustanability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Citrus fruits, particularly mandarin orange and lemon, represent one of Nepal's most important fruit crops. Nationwide, approximately 60 districts contribute to citrus production, which accounts for 22.37% of total fruit production and 3% of total fruit exports by volume (MoALD, 2017). Recognizing citrus fruits' significant contribution to food security, nutrition, and farmers' livelihoods, the Government of Nepal has implemented various programs to strengthen this sector. Historically cultivated in mid-hill regions, citrus farming has expanded commercially to the Terai region. Current statistics show citrus cultivation across 46,328 hectares, with 26,759 hectares being productive. This yields an annual production of 239,773 metric tons, achieving a productivity rate of 8.96 Mt/ha (MoALD, 2017). The sector's economic importance is underscored by its potential to enhance food security, improve nutrition, generate employment, increase incomes, and contribute to national GDP (Bhandari & Aryal, 2017). Government initiatives, including the National Agriculture Policy 2004 and Agri-Business Promotion Policy 2007 (FAO & MoAC, 2011), have promoted citriculture commercialization. The Fruit Area Expansion Program (2015/16-2036/37) aims to significantly increase citrus cultivation area (from 39,035 ha to 94,554 ha), production (from 222,894 Mt to 593,877 Mt), and productivity (from 8.82 Mt/ha to 10.22 Mt/ha) (Nepal Horticulture Promotion Centre, 2017). However, concerning declines have been observed in Kavre district, particularly in Panauti municipality - a designated orange pocket area. Since 2015, producers have reported deteriorating fruit quality (smaller size, reduced shine, and poor taste) and severe yield reductions. Annual incomes have plummeted from NRs 20,000 to negligible production levels, with most harvests now limited to household consumption. Premature fruit drop has become prevalent, and official data shows production declining from 8,520 tons (2020–2021) to 6,514 tons (2021–2022) (Agriculture Knowledge Center, Kavre). 2. Materials and methods The study employed a combination of field surveys, laboratory analysis, and statistical tools to assess citrus decline in Panauti Municipality. Questionnaires and surveys were conducted among 30 citrus farmers to gather data on farming practices, challenges, and perceptions regarding citrus decline. The survey questions were designed to be clear and aligned with research objectives, ensuring reliable insights.For disease isolation , infected citrus leaves were collected and cultured on suitable agar media in the laboratory. The pathogens were then examined under a microscope for identification. Additionally, the iodine scratch method was used for rapid detection of citrus greening disease, where leaf samples were scratched and treated with iodine solution—no color change to blue or black indicated a negative result. Soil pH analysis was conducted using calibrated pH meters, with three representative soil samples from different orchards. The optimal pH range (6.0–7.5) was assessed to determine nutrient availability for citrus plants. Statistical analysis of survey and field data was performed using MS-Excel to quantify trends and correlations. 2.1 Questionnaires and surveys To assess the prevalence and management of citrus decline, structured questionnaires and surveys were administered to 30 citrus farmers in Panauti Municipality. The survey aimed to collect data on: Farmers’ experience and orchard characteristics (e.g., cultivation history, crop types, orchard size). Production trends (e.g., yield variability, disease incidence). Management practices (e.g., fertilizer use, soil testing, disease control measures). The questionnaire included the following key questions: How many years have you been cultivating citrus? What types of citrus crops do you grow? What is the total number of citrus trees in your orchard? What is the total land area (in hectares) under citrus cultivation? What is the average annual yield (kg) per citrus tree? What are the minimum and maximum yields (kg) observed per tree in a season? Which diseases have you observed in your citrus orchard? Have you noticed any signs of nutrient deficiency in your citrus trees? Do you conduct soil testing to check pH and nutrient levels? What type of fertilizers do you use in your citrus orchard? Questions were designed to be clear, concise, and aligned with the study’s objectives. Open-ended responses were categorized during analysis to quantify trends (e.g., disease prevalence, yield gaps). Survey data were cross-validated with field observations and laboratory results to ensure reliability. 2.2 Isolation of diseases The leaves collected from the affected citrus orchards were taken to the laboratory where with the help of suitable agar medium the diseases were isolated and observed under microscope to identify the pathogen. Standard protocols from the Plant Pathology Laboratory Manual were followed for sample processing and isolation. The cultured pathogens were compared with known reference specimens for accurate identification. 2.3 Iodine scratch method This method is used for rapid detection of one of the major citrus diseases i.e. citrus greening disease. The diseased leaf sample is scratched over 20 times with the help of small cut sand paper, then the scratched leaf sample is dipped into iodine solution and If there is no change in brown color of solution into blue or black then it indicates the negative result or absence of citrus greening disease. This technique is recommended by the National Citrus Research Center for preliminary field diagnosis. The results were recorded and verified through repeated testing. 2.4 Determination of soil pH Maintaining the right pH range, typically between 6.0 and 7.5, is vital for nutrient availability, as it ensures that essential elements are accessible to the citrus plants. Three soil samples from three different citrus orchards were brought as a representative of soil of citrus orchards of that area. It is ensured that the pH meter is properly calibrated before use. The pH meter's electrode is immersed in pH 7.0 buffer solution and is adjusted to read pH 7.0. Soil sampling followed the guidelines provided in the Soil Analysis Handbook for Horticultural Crops. Multiple readings were taken for each sample to ensure accuracy. 2.5 Statistical analysis Data generated from surveys and field visits were analyzed using MS-Excel. The software's built-in statistical functions were utilized for calculating means and standard deviations. Results were presented in tables and charts for better visualization of the data patterns. All raw data were preserved for future reference and verification. 3. Result and Discussion 3.1 Survey Findings The survey revealed important insights into citrus farming practices and challenges in the study area. Farmers' experience in citrus cultivation showed significant variation, with the largest proportion (30%) having 10-20 years of experience. This was followed by 23.33% with 15-20 years, 20% with 5-10 years, 13.33% with 20-25 years, and 6.67% with 25-30 years of cultivation experience. Citrus production in the study area was dominated by orange trees, which accounted for 2,839 trees (88.36% of total citrus plants), while lemon trees constituted 374 trees (11.64%). The total area under citrus cultivation spanned 10 hectares, with orange cultivation covering 8.77 hectares (88%) and lemon cultivation occupying 1.24 hectares (12%). Yield analysis indicated an average annual production of 29 kg per tree, with yields ranging from 5 kg (minimum) to 70 kg (maximum) per tree. The survey data, corroborated by field observations, demonstrated that most citrus trees exhibited signs of nutrient deficiency and were affected by various fungal diseases, highlighting significant challenges in orchard management. 3.2 Laboratory analysis result Iodine scratch method Citrus greening being one of the major diseases prevailing in the citrus orchards of Nepal, Firstly the iodine scratch test for the rapid detection of citrus greening disease is carried out as shown in figure 1. It is one of the widely used method for the rapid detection of citrus greening disease. No change in color in any of the leaf’s samples. Since there was no any detection of change in color in the iodine solution, it can be concluded that the leaf sample are not diseased with citrus greening disease. PCR has been considered as the most effective, quick and correct methodology of Huanglongbing detection in Vietnam (Taba et. al., 2006). The method gave 89% accuracy over PCR test (Onuki, et. al., 2002). Similarly, a report showed the result varied in between iodine and PCR tests by 8.9% and 3% for negative and positive reactions respectively (Hong and Truc, 2003). Hence, this technique of starch testing with 1.2% iodine solution is reliable enough to detect HLB in citrus trees. Isolation of diseases The laboratory analysis of the citrus leaf samples indicated no presence of the two major bacterial diseases affecting citrus—citrus greening (Huanglongbing, HLB) and citrus canker—suggesting these pathogens are not currently prevalent in the sampled area. However, fungal infections were identified as significant concerns, with powdery mildew (Oidium spp.) and sooty mold (Capnodium spp.) clearly observed. Powdery mildew appeared as white, powdery growth on the leaves (Figure 2), while microscopic examination confirmed fungal hyphae and conidia (Figure 3). Similarly, sooty mold presented as dark, soot-like patches (Figure 4), with microscopic analysis revealing spores and mycelial structures (Figure 5). These fungal infections can hinder photosynthesis and overall plant health, necessitating appropriate fungicidal treatments. Additionally, the samples exhibited signs of infestation by various pests, including aphids, fruit flies, scales, mites, thrips, and ants, all of which contribute to reduced citrus growth and yield. Aphids and scales sap nutrients while promoting sooty mold growth, fruit flies damage developing fruits, and mites and thrips cause leaf discoloration and deformation. Ants, often associated with aphid farming, further exacerbate the problem. To mitigate these issues, integrated pest management (IPM) strategies—such as targeted pesticide use, biological controls, and improved cultural practices like pruning and field sanitation—are recommended. The findings highlight the need for proactive fungal and pest control measures to ensure healthy citrus production in the region. Soil Ph The laboratory analysis of soil from the Panauti municipality for the determination of soil Ph concluded that the pH ranges from 6.5-7 which is the optimum soil Ph for the growth and production of citrus which emphasizes that maintaining this pH range provides an ideal environment for citrus trees to absorb essential nutrients and thrive. Table 1 : pH value of different soil sample Soil sample no Name of respondents Ph 2 Gita Sapkota 6.5 5 Ambika Sapkota 6.93 12 Loknath Sapkota 6.8 Conclusion The study conducted through 30 respondents and research carried out with 30 leaf samples from the field site gives us insight about their overall socio-demographic characteristics, their citrus cultivation practices, their problems and overall dimensions of agriculture in the context of Panauti municipality. With the isolation of disease, it was observed that rather than presence of citrus canker, the presence of fungal disease like powdery mildew, sooty mold, nutrient deficiency, lack of selection of proper cultivar, lack of proper management approaches were the major factors contributing to the citrus decline this area for the last 7-8 years. The low rate of farmers using recommended dose of manure and fertilizer, their dependency in rain-fed irrigation, use of geographically on-appropriate cultivars, only few farmers performing training, pruning in citrus orchards, these all practices evidently show their low participation and adoption level towards improved and commercial citrus production. In essence, the intricate web of nutrient deficiency, fungal disease, and cultivar mismanagement has contributed to the distressing decline observed in citrus orchards. Addressing these challenges requires a concerted effort from researchers, farmers, and policymakers to implement sustainable and science-based strategies. By fortifying the foundation of citrus cultivation through comprehensive solutions, the trajectory of decline can be reversed, ensuring the prosperity and longevity of citrus orchards for generations to come. 4. Limitations of the Study This study had several limitations that should be considered when interpreting the results. First, the research was confined to Panauti municipality in Kavre district, which may not fully represent the diverse citrus-growing conditions across Nepal. Second, while fungal and bacterial pathogens were examined, other potential contributors to citrus decline—such as viral infections, nematodes, or abiotic stressors like climate variability—were not thoroughly investigated. Additionally, the relatively small sample size of 30 farmers and 30 leaf samples might limit the broader applicability of the findings. These constraints highlight the need for caution when extrapolating the results to other regions or citrus cultivation systems. 5. Recommendations for Future Work To build on this research, future studies should expand the geographic scope to include multiple citrus-growing regions in Nepal, ensuring a more comprehensive assessment of the factors driving citrus decline. Investigating the combined effects of biotic and abiotic stressors such as soil health, water management, and climate change could provide deeper insights into the syndrome. Furthermore, developing and testing integrated management strategies, including resistant cultivars, precision nutrient application, and biocontrol methods, would be valuable for mitigating citrus decline. Finally, implementing extension programs to educate farmers about early disease detection and sustainable orchard management practices, integrating with emerging technologies like AI, IoT Sensors (Ritu Raj Lamsal et al.) could be beneficial for the citrus industry in the long term. Declarations All participants in this study provided verbal consent to participate after being informed of the study’s purpose, procedures, and, confidentiality and voluntary participation. Conflict of Interest: Authors declare no conflict of interest Acknowledgments This Authors would like to acknowledge the support extended by Panauti Municipality, Nepal during the research. References Adhikari, D. & Joshi, S., 2019 . Fruit rotting flies in citrus farming, Sindhuli, Nepal: Chinese citrus fly ( Bactrocera minax ). Ansari, A.M., Sah, A., Ahmed, E., 2011. Studies on rejuvenation of poor bearing citrus plants. Prog. Agri. 11 (2), 491–494. Ashraf, S., Khan, G.A., Ali, S., Iftikhar, M., Mehmood, N., 2014. 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Assessment of lime and lemon production in Nepal. J. Inst. Agric. Anim. Sci. 23, 49–58. Dhillon, B. & Singh, J., 1965. Relationship Between Soil Moisture and Fruit Drop in Mandarin (Citrus Reticulata Blanco) Var. Nagpuri1. Indian Journal of Horticulture, 22(3&4), pp. 309-313. Dhingra, D. & Kanwar, J., 1963. Soil factors and chlorosis of citrus. Punjab Hort. J, 3(1), pp. 54-59. Dorji, K., Lakey, L., Chophel, S., Dorji, S.D., Tamang, B., 2016. Adoption of improved citrus orchard management practices: a micro study from Drujegang growers, Dagana, Bhutan. Agric. Food Secur. 5 (1), 1–8. Erwin, D. & Ribeiro, O., 1996. Phytophthora diseases worldwide : American Phyto pathological Society (APS Press). Gauchan, D., 1994. An Optimum planning for integrating citrus in Nepalese hill farming systems: Chiang Mai University. Graham, J. & Eichelberger, E., 2015. Citrus phytophthora diseases: Management challenges and successes. Journal of Citrus Pathology, 2(1). Kaini, B.R. 2004. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7250604","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":493041565,"identity":"40c9f601-3755-45df-8f12-1cbc655d6196","order_by":0,"name":"Neelam Limbu","email":"","orcid":"","institution":"2Research Institute of Agriculture and Applied Science, Nepal","correspondingAuthor":false,"prefix":"","firstName":"Neelam","middleName":"","lastName":"Limbu","suffix":""},{"id":493041566,"identity":"761e27f5-ec81-4406-81e2-edf68e844c7b","order_by":1,"name":"Ritu Raj 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observation\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7250604/v1/70e39b725d523ceffc121df8.png"},{"id":88397690,"identity":"6be2c643-6065-4564-97d0-6ef4d66abf35","added_by":"auto","created_at":"2025-08-06 06:24:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2876084,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7250604/v1/c9cf1904-1773-4150-a71d-e459b6b2bdd5.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003ePrevalence and Severity of Citrus Decline and Its Management in Orchards of Panauti Municipality, Nepal\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCitrus fruits, particularly mandarin orange and lemon, represent one of Nepal's most important fruit crops. Nationwide, approximately 60 districts contribute to citrus production, which accounts for 22.37% of total fruit production and 3% of total fruit exports by volume (MoALD, 2017). Recognizing citrus fruits' significant contribution to food security, nutrition, and farmers' livelihoods, the Government of Nepal has implemented various programs to strengthen this sector. Historically cultivated in mid-hill regions, citrus farming has expanded commercially to the Terai region. Current statistics show citrus cultivation across 46,328 hectares, with 26,759 hectares being productive. This yields an annual production of 239,773 metric tons, achieving a productivity rate of 8.96 Mt/ha (MoALD, 2017). The sector's economic importance is underscored by its potential to enhance food security, improve nutrition, generate employment, increase incomes, and contribute to national GDP (Bhandari \u0026amp; Aryal, 2017).\u003c/p\u003e\u003cp\u003eGovernment initiatives, including the National Agriculture Policy 2004 and Agri-Business Promotion Policy 2007 (FAO \u0026amp; MoAC, 2011), have promoted citriculture commercialization. The Fruit Area Expansion Program (2015/16-2036/37) aims to significantly increase citrus cultivation area (from 39,035 ha to 94,554 ha), production (from 222,894 Mt to 593,877 Mt), and productivity (from 8.82 Mt/ha to 10.22 Mt/ha) (Nepal Horticulture Promotion Centre, 2017).\u003c/p\u003e\u003cp\u003eHowever, concerning declines have been observed in Kavre district, particularly in Panauti municipality - a designated orange pocket area. Since 2015, producers have reported deteriorating fruit quality (smaller size, reduced shine, and poor taste) and severe yield reductions. Annual incomes have plummeted from NRs 20,000 to negligible production levels, with most harvests now limited to household consumption. Premature fruit drop has become prevalent, and official data shows production declining from 8,520 tons (2020\u0026ndash;2021) to 6,514 tons (2021\u0026ndash;2022) (Agriculture Knowledge Center, Kavre).\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003eThe study employed a combination of field surveys, laboratory analysis, and statistical tools to assess citrus decline in Panauti Municipality. \u003cstrong\u003eQuestionnaires and surveys\u003c/strong\u003e were conducted among 30 citrus farmers to gather data on farming practices, challenges, and perceptions regarding citrus decline. The survey questions were designed to be clear and aligned with research objectives, ensuring reliable insights.For \u003cstrong\u003edisease isolation\u003c/strong\u003e, infected citrus leaves were collected and cultured on suitable agar media in the laboratory. The pathogens were then examined under a microscope for identification. Additionally, the \u003cstrong\u003eiodine scratch method\u003c/strong\u003e was used for rapid detection of citrus greening disease, where leaf samples were scratched and treated with iodine solution\u0026mdash;no color change to blue or black indicated a negative result.\u003cstrong\u003eSoil pH analysis\u003c/strong\u003e was conducted using calibrated pH meters, with three representative soil samples from different orchards. The optimal pH range (6.0\u0026ndash;7.5) was assessed to determine nutrient availability for citrus plants.\u003cstrong\u003eStatistical analysis\u003c/strong\u003e of survey and field data was performed using MS-Excel to quantify trends and correlations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1 Questionnaires and surveys\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo assess the prevalence and management of citrus decline, structured questionnaires and surveys were administered to 30 citrus farmers in Panauti Municipality. The survey aimed to collect data on:\u003c/p\u003e\n\u003col start=\"1\" type=\"A\" style=\"list-style-type: upper-alpha;\"\u003e\n \u003cli\u003eFarmers\u0026rsquo; experience and orchard characteristics (e.g., cultivation history, crop types, orchard size).\u003c/li\u003e\n \u003cli\u003eProduction trends\u0026nbsp;(e.g., yield variability, disease incidence).\u003c/li\u003e\n \u003cli\u003eManagement practices (e.g., fertilizer use, soil testing, disease control measures).\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eThe questionnaire included the following key questions:\u003c/p\u003e\n\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003eHow many years have you been cultivating citrus?\u003c/li\u003e\n \u003cli\u003eWhat types of citrus crops do you grow?\u003c/li\u003e\n \u003cli\u003eWhat is the total number of citrus trees in your orchard?\u003c/li\u003e\n \u003cli\u003eWhat is the total land area (in hectares) under citrus cultivation?\u003c/li\u003e\n \u003cli\u003eWhat is the average annual yield (kg) per citrus tree?\u003c/li\u003e\n \u003cli\u003eWhat are the minimum and maximum yields (kg) observed per tree in a season?\u003c/li\u003e\n \u003cli\u003eWhich diseases have you observed in your citrus orchard?\u003c/li\u003e\n \u003cli\u003eHave you noticed any signs of nutrient deficiency in your citrus trees?\u003c/li\u003e\n \u003cli\u003eDo you conduct soil testing to check pH and nutrient levels?\u003c/li\u003e\n \u003cli\u003eWhat type of fertilizers do you use in your citrus orchard?\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eQuestions were designed to be clear, concise, and aligned with the study\u0026rsquo;s objectives. Open-ended responses were categorized during analysis to quantify trends (e.g., disease prevalence, yield gaps). Survey data were cross-validated with field observations and laboratory results to ensure reliability.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Isolation of diseases\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe leaves collected from the affected citrus orchards were taken to the laboratory where with the help of suitable agar medium the diseases were isolated and observed under microscope to identify the pathogen. Standard protocols from the Plant Pathology Laboratory Manual were followed for sample processing and isolation. The cultured pathogens were compared with known reference specimens for accurate identification.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Iodine scratch method\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis method is used for rapid detection of one of the major citrus diseases i.e. citrus greening disease. The diseased leaf sample is scratched over 20 times with the help of small cut sand paper, then the scratched leaf sample is dipped into iodine solution and If there is no change in brown color of solution into blue or black then it indicates the negative result or absence of citrus greening disease. This technique is recommended by the National Citrus Research Center for preliminary field diagnosis. The results were recorded and verified through repeated testing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Determination of soil pH\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMaintaining the right pH range, typically between 6.0 and 7.5, is vital for nutrient availability, as it ensures that essential elements are accessible to the citrus plants. Three soil samples from three different citrus orchards were brought as a representative of soil of citrus orchards of that area. It is ensured that the pH meter is properly calibrated before use. The pH meter\u0026apos;s electrode is immersed in pH 7.0 buffer solution and is adjusted to read pH 7.0. Soil sampling followed the guidelines provided in the Soil Analysis Handbook for Horticultural Crops. Multiple readings were taken for each sample to ensure accuracy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Statistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData generated from surveys and field visits were analyzed using MS-Excel. The software\u0026apos;s built-in statistical functions were utilized for calculating means and standard deviations. Results were presented in tables and charts for better visualization of the data patterns. All raw data were preserved for future reference and verification.\u003c/p\u003e"},{"header":"3. Result and Discussion","content":"\u003cp\u003e\u003cstrong\u003e3.1 Survey Findings\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe survey revealed important insights into citrus farming practices and challenges in the study area. Farmers\u0026apos; experience in citrus cultivation showed significant variation, with the largest proportion (30%) having 10-20 years of experience. This was followed by 23.33% with 15-20 years, 20% with 5-10 years, 13.33% with 20-25 years, and 6.67% with 25-30 years of cultivation experience. Citrus production in the study area was dominated by orange trees, which accounted for 2,839 trees (88.36% of total citrus plants), while lemon trees constituted 374 trees (11.64%). The total area under citrus cultivation spanned 10 hectares, with orange cultivation covering 8.77 hectares (88%) and lemon cultivation occupying 1.24 hectares (12%). Yield analysis indicated an average annual production of 29 kg per tree, with yields ranging from 5 kg (minimum) to 70 kg (maximum) per tree. The survey data, corroborated by field observations, demonstrated that most citrus trees exhibited signs of nutrient deficiency and were affected by various fungal diseases, highlighting significant challenges in orchard management.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Laboratory analysis result\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIodine\u0026nbsp;scratch\u0026nbsp;method\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCitrus greening being one of the major diseases prevailing in the citrus orchards of Nepal, Firstly the iodine scratch test for the rapid detection of citrus greening disease is carried out as shown in figure 1. It is one of the widely used method for the rapid detection of citrus greening disease. No change in color in any of the leaf\u0026rsquo;s samples. Since there was no any detection of change in color in the iodine solution, it can be concluded that the leaf sample are not diseased with citrus greening disease. PCR has been considered as the most effective, quick and correct methodology of Huanglongbing detection in Vietnam (Taba et. al., 2006). The method gave 89% accuracy over PCR test (Onuki, et. al., 2002). Similarly, a report showed the result varied in between iodine and PCR tests by 8.9% and 3% for negative and positive reactions respectively (Hong and Truc, 2003). Hence, this technique of starch testing with 1.2% iodine solution is reliable enough to detect HLB in citrus trees.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eIsolation of diseases\u003c/h2\u003e\n\u003cp\u003eThe laboratory analysis of the citrus leaf samples indicated no presence of the two major bacterial diseases affecting citrus\u0026mdash;citrus greening (Huanglongbing, HLB) and citrus canker\u0026mdash;suggesting these pathogens are not currently prevalent in the sampled area. However, fungal infections were identified as significant concerns, with powdery mildew (Oidium spp.) and sooty mold (Capnodium spp.) clearly observed. Powdery mildew appeared as white, powdery growth on the leaves (Figure 2), while microscopic examination confirmed fungal hyphae and conidia (Figure 3). Similarly, sooty mold presented as dark, soot-like patches (Figure 4), with microscopic analysis revealing spores and mycelial structures (Figure 5). These fungal infections can hinder photosynthesis and overall plant health, necessitating appropriate fungicidal treatments. Additionally, the samples exhibited signs of infestation by various pests, including aphids, fruit flies, scales, mites, thrips, and ants, all of which contribute to reduced citrus growth and yield. Aphids and scales sap nutrients while promoting sooty mold growth, fruit flies damage developing fruits, and mites and thrips cause leaf discoloration and deformation. Ants, often associated with aphid farming, further exacerbate the problem. To mitigate these issues, integrated pest management (IPM) strategies\u0026mdash;such as targeted pesticide use, biological controls, and improved cultural practices like pruning and field sanitation\u0026mdash;are recommended. The findings highlight the need for proactive fungal and pest control measures to ensure healthy citrus production in the region.\u003c/p\u003e\n\u003ch2\u003eSoil Ph\u003c/h2\u003e\n\u003cp\u003eThe laboratory analysis of soil from the Panauti municipality for the determination of soil Ph concluded that the pH ranges from 6.5-7 which is the optimum soil Ph for the growth and production of citrus which emphasizes that maintaining this pH range provides an ideal environment for citrus trees to absorb essential nutrients and thrive.\u003c/p\u003e\n\u003cp\u003eTable 1 : pH value of different soil sample\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 109px;\"\u003e\n \u003cp\u003eSoil sample no\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003eName of respondents\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003ePh\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 109px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003eGita Sapkota\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 109px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003eAmbika Sapkota\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e6.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 109px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003eLoknath Sapkota\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e6.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study conducted through 30 respondents and research carried out with 30 leaf samples from the field site gives us insight about their overall socio-demographic characteristics, their citrus cultivation practices, their problems and overall dimensions of agriculture in the context of Panauti municipality. With the isolation of disease, it was observed that rather than presence of citrus canker, the presence of fungal disease like powdery mildew, sooty mold, nutrient deficiency, lack of selection of proper cultivar, lack of proper management approaches were the major factors contributing to the citrus decline this area for the last 7-8 years. The low rate of farmers using recommended dose of manure and fertilizer, their dependency in rain-fed irrigation, use of geographically on-appropriate cultivars, only few farmers performing training, pruning in citrus orchards, these all practices evidently show their low participation and adoption level towards improved and commercial citrus production. In essence, the intricate web of nutrient deficiency, fungal disease, and cultivar mismanagement has contributed to the distressing decline observed in citrus orchards. \u0026nbsp;Addressing these challenges requires a concerted effort from researchers, farmers, and policymakers to implement sustainable and science-based strategies. By fortifying the foundation of citrus cultivation through comprehensive solutions, the trajectory of decline can be reversed, ensuring the prosperity and longevity of citrus orchards for generations to come.\u003c/p\u003e"},{"header":"4. Limitations of the Study","content":"\u003cp\u003eThis study had several limitations that should be considered when interpreting the results. First, the research was confined to Panauti municipality in Kavre district, which may not fully represent the diverse citrus-growing conditions across Nepal. Second, while fungal and bacterial pathogens were examined, other potential contributors to citrus decline\u0026mdash;such as viral infections, nematodes, or abiotic stressors like climate variability\u0026mdash;were not thoroughly investigated. Additionally, the relatively small sample size of 30 farmers and 30 leaf samples might limit the broader applicability of the findings. These constraints highlight the need for caution when extrapolating the results to other regions or citrus cultivation systems.\u003c/p\u003e"},{"header":"5. Recommendations for Future Work","content":"\u003cp\u003eTo build on this research, future studies should expand the geographic scope to include multiple citrus-growing regions in Nepal, ensuring a more comprehensive assessment of the factors driving citrus decline. Investigating the combined effects of biotic and abiotic stressors such as soil health, water management, and climate change could provide deeper insights into the syndrome. Furthermore, developing and testing integrated management strategies, including resistant cultivars, precision nutrient application, and biocontrol methods, would be valuable for mitigating citrus decline. Finally, implementing extension programs to educate farmers about early disease detection and sustainable orchard management practices, integrating with emerging technologies like AI, IoT Sensors (Ritu Raj Lamsal et al.) could be beneficial for the citrus industry in the long term.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cspan\u003eAll participants in this study provided verbal consent to participate after being informed of the study\u0026rsquo;s purpose, procedures, and, confidentiality and voluntary participation.\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConflict of Interest:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors declare no conflict of interest\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis Authors would like to acknowledge the support extended by Panauti Municipality, Nepal during the research.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAdhikari, D. \u0026amp; Joshi, S., 2019 . \u003cem\u003eFruit rotting flies in citrus farming,\u0026nbsp;\u003c/em\u003eSindhuli, Nepal: Chinese\u0026nbsp;citrus fly\u0026nbsp;(\u003cem\u003eBactrocera\u0026nbsp;minax\u003c/em\u003e).\u003c/li\u003e\n \u003cli\u003eAnsari, A.M., Sah, A., Ahmed, E., 2011. 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Rejuvenation of declined citrus trees. \u003cem\u003eNepalese Horticulture, vol.4,\u0026nbsp;\u003c/em\u003eIssue 1 pp.1-7.\u003c/li\u003e\n \u003cli\u003eKumar, G., Thakur, N., Singh, G., Tomar, S., 2017. Effect of integrated nutrient management on growth, yield and fruit quality of sweet orange (citrus sinensis L.) cv.\u003c/li\u003e\n \u003cli\u003eKumari, S., Singh, A.K., Kumar, S., Shah, V.K., 2020. A hidden problem: \u003cem\u003eLoranthus falcatus\u003c/em\u003e L. \u0026amp; \u003cem\u003eLoranthus parasitica\u003c/em\u003e L. For horticulture crops. \u003cem\u003eAgricult. Food eNewslett. 2 (5),\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003eLamsal, R. R., Acharya, U. K., Karthikeyan, P., Otero, P., \u0026amp; Ariza, A. (2024). Implementing Internet of Things for Real-Time Monitoring and Regulation of Off-Season Grafting and Post-Harvest Storage in Citrus Cultivation: A Case Study from the Hilly Regions of Nepal.\u0026nbsp;AgriEngineering,\u0026nbsp;6(3), 2082-2100. https://doi.org/10.3390/agriengineering6030122\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003eMishra, A., Karimi, D., Ehsani, R. \u0026amp; Albrigo, L., 2011. Evaluation of an active optical\u0026nbsp;sensor for detection of Huanglongbing (HLB) disease. \u003cem\u003eBiosystems engineering,\u0026nbsp;\u003c/em\u003e110(3),\u0026nbsp;pp.\u0026nbsp;302-309.\u003c/li\u003e\n \u003cli\u003eNARDF,\u0026nbsp;2015. \u003cem\u003eProject compilation report,\u0026nbsp;\u003c/em\u003eSinghdurbar,\u0026nbsp;Kathmandu:\u0026nbsp;National\u0026nbsp;Agricultural\u0026nbsp;Research\u0026nbsp;and Development Fund.\u003c/li\u003e\n \u003cli\u003e\u0026nbsp;Nath, R. \u0026amp; Sikha, D., 2019. Insect pests of citrus and their management. \u003cem\u003eInt J Pl Pr,\u0026nbsp;\u003c/em\u003e12(2),\u0026nbsp;pp. 188-96.\u003c/li\u003e\n \u003cli\u003e\u0026nbsp;NCDP, 2021. \u003cem\u003eNational Citrus Development Program,\u0026nbsp;\u003c/em\u003eNepal:\u0026nbsp;Fruit\u0026nbsp;Development\u0026nbsp;Directorate,\u0026nbsp;MoALD.\u003c/li\u003e\n \u003cli\u003eNCRP, 2019. \u003cem\u003eAnnual Report,\u0026nbsp;\u003c/em\u003eParipatle\u0026nbsp;Dhankuta:\u0026nbsp;National\u0026nbsp;Citrus\u0026nbsp;Research\u0026nbsp;Programme.\u003c/li\u003e\n \u003cli\u003eRitu Raj Lamsal, Prahlad Acharya, Rijan Pokhrel et al. Integrating Machine Learning and RAG-Based Chatbot for Mandarin Orange Disease Detection in Hilly Region of Nepal, 27 February 2025, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-6105402/v1]\u003c/li\u003e\n \u003cli\u003eShrestha, R. L. 2066 (B.S.).\u003cem\u003e\u0026nbsp;Causes of citrus decline and management technology. National Citrus Research Program,\u0026nbsp;\u003c/em\u003eParipatle, Dhankuta Nepal.t. Subedi Fulprasad, D. D. Dhakal and N.P. Khanal, 2003\u003cem\u003e. Integrated Citrus Decline Management Proceeding (Nepali version).\u0026nbsp;\u003c/em\u003eIAAS, Rampur and DADOs of Tanahu, Gorkha and Lamjung.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Madan Bhandari University of Science and Technology, ","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Citrus cultivation, citrus disease, isolation of disease, management practices, sustanability","lastPublishedDoi":"10.21203/rs.3.rs-7250604/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7250604/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCitrus Decline, a complex and devastating disorder caused by various biotic and abiotic factors has emerged as a significant challenge for citrus cultivation in Nepal. This study on \u0026ldquo;Prevalence and severity of citrus decline and its management practices in citrus orchards of Panauti municipality\u0026rdquo; was conducted in Panauti municipality of Kavre district of Nepal during the month of April/May - July/August, 2023 with the combination of survey and research. Survey was conducted with 30 respondents randomly and interviewed with questionnaire to extract data on comprehensive overview of citrus decline and its management practices, whereas research was conducted with 30 different leaves samples for disease isolation along with the determination of pH from the soil samples collected from the study site. The survey findings showed that the total number of 3213 citrus trees under 10 ha of land was done, with 98% of farmers facing citrus decline problem where disease incidence of 41% fungal, 34% parasitic, 5% bacterial, 15% viral and 5% others were observed and pest incidence with 34.48% leaf miner,28.74% fruit fly, 19.54% mites, 17.24% aphids were observed. Similarly in management practices, 86.66% of farmers were use farm yard manure but only 16.66% of them use recommended dose of manure and fertilizers, the training, pruning was performed by only 6.66% of farmers, 85% of farmers were seen intercropping the citrus orchards with pumpkin, cucumber, tomato etc. In the context of research, 30 leaves sample were isolated in different agar media with the positive result of powdery mildew in 20 leaves sample, sooty mold in 28 leaves samples and negative result in all leaves sample isolated suspecting of Citrus canker. Iodine scratch method for rapid detection of citrus greening disease was done and negative result in all leaves samples were obtained. Citrus decline stands as a significant constraint in citrus farming in Nepal, urging prior attention and the implementation of improved management practices to safeguard the sustainability and prosperity of the citrus industry.\u003c/p\u003e","manuscriptTitle":"Prevalence and Severity of Citrus Decline and Its Management in Orchards of Panauti Municipality, Nepal","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-06 06:00:27","doi":"10.21203/rs.3.rs-7250604/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"34b2c033-3a56-47f8-9a0a-824e6e33bedc","owner":[],"postedDate":"August 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":52719077,"name":"Horticulture"},{"id":52719078,"name":"Agricultural Engineering"}],"tags":[],"updatedAt":"2025-08-06T06:00:27+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-06 06:00:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7250604","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7250604","identity":"rs-7250604","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}