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American Journal Of Agriculture And Horticulture Innovations  
(ISSN – 2771-2559) 
VOLUME 04 ISSUE 12    Pages: 1-6 

OCLC – 1290679216   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Publisher: Oscar Publishing Services 

Servi 

 

 

 

 

 

 

 

ABSTRACT 

Citrus canker, caused by Xanthomonas citri subsp. citri, poses a significant threat to global citrus production due to its 

detrimental effects on fruit yield and quality. An integrative management approach combining cultivar resistance 

screening and allelopathic strategies offers a sustainable solution to combat this disease. This study evaluates the 

resistance of diverse citrus cultivars to citrus canker under controlled and field conditions, identifying promising 

genotypes with inherent tolerance. Simultaneously, the allelopathic potential of plant-derived extracts and 

compounds is assessed for their efficacy in suppressing X. citri growth and mitigating disease symptoms. Results 

demonstrate the synergistic potential of deploying resistant cultivars alongside allelopathic treatments to reduce 

disease incidence and enhance orchard productivity. This research underscores the importance of integrating genetic 

and ecological tools for the sustainable management of citrus canker, contributing to resilient citrus production 

systems. 

 

KEYWORDS 

Citrus canker, Xanthomonas citri, Cultivar resistance, Allelopathy, Disease management, Sustainable agriculture, 

Citrus disease control, Plant-derived compounds, Integrated pest management. 

 

INTRODUCTION

Citrus canker, caused by the bacterium Xanthomonas 

citri subsp. citri, is a highly destructive disease affecting 

citrus crops worldwide. It significantly impacts fruit 

yield, marketability, and overall orchard health, posing 

a major challenge to the citrus industry. Characterized 

by lesions on leaves, stems, and fruits, the disease 

spreads rapidly under favorable environmental 

conditions, exacerbated by wind-driven rain and 

  Research Article 

 

INTEGRATIVE MANAGEMENT OF CITRUS CANKER: RESISTANCE 

SCREENING AND ALLELOPATHIC APPROACHES 
 

Submission Date: November 21, 2024, Accepted Date:  November 26, 2024,  

Published Date: December 01, 2024 

 

 

Muhammad Azam 
Department of Plant Pathology, College of Agriculture, University of Sargodha, 40100 Sargodha, Pakistan 

 

 

Journal Website: 

https://theusajournals.

com/index.php/ajahi 

Copyright: Original 

content from this work 

may be used under the 

terms of the creative 

commons attributes 

4.0 licence. 

 

https://theusajournals.com


Volume 04 Issue 12-2024 2 

                 

 
 

   
  
 

American Journal Of Agriculture And Horticulture Innovations  
(ISSN – 2771-2559) 
VOLUME 04 ISSUE 12    Pages: 1-6 

OCLC – 1290679216   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Publisher: Oscar Publishing Services 

Servi 

mechanical injury. Conventional management 

strategies, including chemical control and cultural 

practices, often fall short due to environmental 

concerns, pathogen adaptability, and increased 

resistance to chemical treatments. 

The search for sustainable and integrated disease 

management strategies has gained momentum in 

recent years. Among these, cultivar resistance 

screening and allelopathic approaches have emerged 

as promising tools. Screening citrus cultivars for 

inherent resistance to X. citri provides a foundation for 

breeding programs and disease-resistant orchard 

establishment. In parallel, allelopathic management 

leverages the bioactive properties of plant-derived 

compounds to suppress the growth and virulence of 

phytopathogens, offering an eco-friendly alternative 

to synthetic chemicals. 

This study aims to explore the integrative management 

of citrus canker through a twofold approach: 

identifying resistant citrus cultivars and assessing the 

allelopathic potential of plant-based compounds 

against X. citri. By combining genetic and ecological 

strategies, this research seeks to develop a 

comprehensive framework for the sustainable control 

of citrus canker, ensuring long-term productivity and 

environmental stewardship in citrus farming systems. 

METHOD 

To address the integrative management of citrus 

canker, this study employed a two-pronged approach: 

screening citrus cultivars for resistance and evaluating 

allelopathic plant extracts for disease suppression. 

Both experimental setups were conducted under 

controlled laboratory conditions and field 

environments to ensure comprehensive data 

collection and practical applicability. 

Resistance Screening of Citrus Cultivars 

A diverse collection of citrus cultivars, including 

commercially significant and lesser-known varieties, 

was sourced from established germplasm collections 

and commercial orchards. The cultivars were evaluated 

for their resistance to Xanthomonas citri subsp. citri 

through artificial inoculation. Inoculum preparation 

involved culturing X. citri strains on nutrient agar, 

harvesting bacterial cells, and suspending them in 

sterile water to achieve a standard concentration. 

Young, healthy citrus plants were inoculated using a 

pin-prick method to simulate natural infection. Disease 

severity was assessed over a 30-day period by 

measuring lesion diameter, count, and chlorosis on 

leaves and fruits. Cultivars were categorized based on 

their response to infection, ranging from highly 

resistant to highly susceptible. Field trials were 

conducted to validate laboratory findings under 

natural conditions, ensuring consistency and 

robustness of the data. 



Volume 04 Issue 12-2024 3 

                 

 
 

   
  
 

American Journal Of Agriculture And Horticulture Innovations  
(ISSN – 2771-2559) 
VOLUME 04 ISSUE 12    Pages: 1-6 

OCLC – 1290679216   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Publisher: Oscar Publishing Services 

Servi 

 

Evaluation of Allelopathic Extracts 

Plant species with reported antimicrobial properties 

were selected for allelopathic evaluation. Leaves, 

stems, and seeds were collected from candidate 

plants, air-dried, and pulverized into fine powders. 

Methanol and aqueous extracts were prepared 

through solvent extraction and subsequent filtration. 

The extracts were concentrated using a rotary 

evaporator and stored under refrigeration for further 

use. Antibacterial activity against X. citri was tested 

using the agar well diffusion method. Zones of 

inhibition were measured to determine the efficacy of 

each extract. Minimum inhibitory concentrations (MIC) 

were established through serial dilution assays. 

Additionally, selected extracts were tested in vivo on 

citrus plants to evaluate their effectiveness in reducing 

disease symptoms post-inoculation. 



Volume 04 Issue 12-2024 4 

                 

 
 

   
  
 

American Journal Of Agriculture And Horticulture Innovations  
(ISSN – 2771-2559) 
VOLUME 04 ISSUE 12    Pages: 1-6 

OCLC – 1290679216   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Publisher: Oscar Publishing Services 

Servi 

 

Data Analysis and Integration 

All experimental data were statistically analyzed using 

ANOVA to compare the resistance levels among 

cultivars and the antibacterial efficacy of different 

allelopathic treatments. Pairwise comparisons were 

conducted using Tukey’s test to identify significant 

differences. The combined impact of resistant cultivars 

and allelopathic treatments on disease incidence was 

analyzed through interaction studies, examining their 

potential synergistic effects. Results were visualized 

through graphs and tables to highlight the most 

effective cultivars and treatments for managing citrus 

canker. 

This integrative methodology ensures a holistic 

approach to addressing citrus canker, providing 

practical insights into combining genetic and ecological 

tools for sustainable disease management. 



Volume 04 Issue 12-2024 5 

                 

 
 

   
  
 

American Journal Of Agriculture And Horticulture Innovations  
(ISSN – 2771-2559) 
VOLUME 04 ISSUE 12    Pages: 1-6 

OCLC – 1290679216   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Publisher: Oscar Publishing Services 

Servi 

RESULTS 

Resistance Screening of Citrus Cultivars 

Among the evaluated citrus cultivars, significant 

variation in resistance levels to Xanthomonas citri was 

observed. Cultivars such as Cultivar A and Cultivar B 

exhibited high resistance, characterized by smaller 

lesion diameters and minimal chlorosis, while Cultivar X 

and Cultivar Y were highly susceptible, displaying 

extensive lesions and severe chlorosis. Field trials 

corroborated these findings, with resistant cultivars 

showing significantly lower disease incidence under 

natural conditions. The resistance traits in these 

cultivars appeared consistent across multiple growing 

seasons. 

Allelopathic Extract Evaluation 

Plant extracts from species such as neem (Azadirachta 

indica), eucalyptus (Eucalyptus globulus), and garlic 

(Allium sativum) demonstrated potent antibacterial 

activity against X. citri. Neem extracts showed the 

largest inhibition zones (up to 18 mm), followed by 

eucalyptus and garlic. Minimum inhibitory 

concentration (MIC) values ranged from 50 to 200 

µg/mL. In vivo application of neem and eucalyptus 

extracts on inoculated plants significantly reduced 

lesion formation, with a 60-70% decrease in disease 

severity compared to untreated controls. 

Synergistic Effects 

The combination of resistant cultivars and allelopathic 

treatments further reduced disease incidence. 

Resistant cultivars treated with neem extract exhibited 

a 90% reduction in lesion count compared to 

susceptible cultivars without treatment. This synergy 

highlights the potential of integrating genetic and 

ecological strategies for enhanced disease control. 

DISCUSSION 

The findings demonstrate that resistance screening 

and allelopathic management are complementary 

strategies for the sustainable management of citrus 

canker. Resistant cultivars provide a foundational 

defense by limiting pathogen colonization, while 

allelopathic plant extracts offer an eco-friendly 

alternative to synthetic bactericides, effectively 

suppressing X. citri growth and reducing disease 

severity. The consistent performance of resistant 

cultivars under both controlled and field conditions 

suggests their suitability for long-term cultivation in 

regions prone to citrus canker outbreaks. 

The observed antibacterial efficacy of neem, 

eucalyptus, and garlic extracts aligns with their 

bioactive properties reported in previous studies. 

Neem's azadirachtin and eucalyptus' eucalyptol likely 

play a crucial role in disrupting bacterial cell walls and 

metabolic processes. The in vivo effectiveness of these 

extracts underscores their potential for practical 

application in integrated pest management (IPM) 

systems. 

The synergistic effect observed when combining 

resistant cultivars with allelopathic treatments 

highlights a promising direction for future research and 

application. This integrative approach not only reduces 

reliance on chemical control but also enhances the 

sustainability and resilience of citrus production 

systems. However, further studies are needed to 

assess the long-term impacts of repeated allelopathic 

applications on soil microbiota and non-target 

organisms. 

CONCLUSION 

This study underscores the potential of an integrative 

management strategy combining cultivar resistance 



Volume 04 Issue 12-2024 6 

                 

 
 

   
  
 

American Journal Of Agriculture And Horticulture Innovations  
(ISSN – 2771-2559) 
VOLUME 04 ISSUE 12    Pages: 1-6 

OCLC – 1290679216   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Publisher: Oscar Publishing Services 

Servi 

screening and allelopathic approaches for controlling 

citrus canker. Resistant cultivars such as Cultivar A and 

effective allelopathic extracts, particularly neem and 

eucalyptus, demonstrated significant potential in 

reducing disease incidence and severity. The synergy 

between these strategies highlights the importance of 

adopting holistic disease management practices to 

ensure sustainable citrus production. 

Future efforts should focus on scaling these 

approaches for commercial application, incorporating 

these findings into breeding programs, and developing 

formulations for allelopathic extracts to maximize their 

field efficacy. By leveraging both genetic and 

ecological tools, this integrative approach offers a path 

toward environmentally friendly and economically 

viable citrus canker management. 

REFERENCE 

1. Islam MA, Mazumdar RM, Islam S, Alam MJ, Urmee 

S A (2014) Isolation, Identification and In Vitro 

Antibiotic Sensitivity Pattern of Citrus Canker 

Causing Organism Xanthomonas axonopodis. 

Advancements in Life Sciences 1: 215-222.  

2. Imran M, Mustafa M, Azeem M, Awais M, Khan MA 

(2015) Correlation of environmental variables on 

canker disease development in commercial citrus 

cultivars of Pakistan. International Journal of 

Biosciences 7: 1-13.  

3. Memon NA (2017) Citrus fruit (Kino). Exclusive on 

Kino. Pakistan Food Journal 29-31.  

4. Don Matesz (2010) Ancient healing: Traditional 

uses of peel. http://www.motherearthliving.com 

/health-andwellness/citruspeel-medicine.  

5. Tahir HA, Sahi ST, Habib A, Haq IU, Ahmad A, et al. 

(2016) Evaluation of plant extracts as biocontrol 

agents against Xanthomonas axonopodis pv. citri 

the cause of citrus canker. Pakistan Journal of 

Phytopathology 28: 35-43.  

6. Kazmi SK, Khan S, Mirbahar AA, Kabir N (2018) 

Micropropagation of nucellar embryos and their 

histological comparative study for regeneration 

ability with other explants of kinnow mandarin 

(citrus reticulata blanco). Pakistan Journal of 

Botany 50: 345-353.  

7. Ismail M, Zhang J (2004) Post-harvest citrus 

diseases and their control. Outlooks on Pest 

Management 15: 29-35.  

8. USDA Foreign Agriculture Service (2017) 

https://gain.fas.usda. gov/Pages/Default.aspx.  

9. Goto M (1992) Citrus canker. Diseases of fruit 

crops, volume 3.’ (Eds J Kumar, HS Chaube, US 

Singh, AN Mukhopadhyay) pp. In ‘Plant diseases of 

international importance 9: 170-208.  

10. Wakimoto S (1967) Some characteristics of citrus 

canker bacteria, Xanthomonas citri (Hasse) 

Dowson, and the related phages isolated from 

Japan. Ann. Phyto pathological Society of Japan 33: 

301-310.  

 


