Journal of Citrus Pathology

This document sets forth the California Department of Food and Agriculture (CDFA), Citrus Pest and Disease Prevention Division’s (CPDPD) statewide Action Plan for Asian citrus psyllid (ACP) and huanglongbing (HLB). This document details the program implemented by CPDPD to sustain and protect California’s commercial citrus production, residential citrus plantings, and naturalresources.

Since its detection in Brazil in 2004, huanglongbin g (HLB) has caused expressive damage to the citrus belt in São Paulo, Minas Gerais and Paraná states. The disease incidence is higher in small groves mainly related to family farming. A risk analysis was performed in citrus regions in São Paulo and Minas Gerais with the objective of identifying the main factors associated with the introduction and spread of HLB in this farm profile. A structured questionnaire was applied comprising 27 closed questions with binary answers (0 or 1 as no or yes ) to 39 citrus growers along 12 municipalities. The regions were selected according to the HLB incidence and relevance of citrus family farming, and farms were assessed by non-probabilistic and convenience sampling. The Analytic Hierarchy Process (AHP) was used to prioritize and weigh specific criteria related to the factors evaluated. Based on the answers, each farm was classified into four risk classes: low (0 to 0.25), intermediate (0.26 to 0.50), high (0.51 to 0.75) and very high (0.76 to 1). The introduction risks into the sampled farms were very high due to the disease occurrence in neighboring areas. However, factors that most contributed to the spread risk within groves were different between the two regions evaluated. In South MG, lack of basic knowledge about HLB pathosystem and low use of control measures were major issues, whereas in East SP the spread was more related to grove age, productivity and density, and absence of area-wide management.

‘Candidatus Liberibacter asiaticus’ (CLas) is a devastating pathogen of citrus associated with Huanglongbing (HLB, citrus greening disease). HLB is economically significant in Asia and has destroyed millions of citrus trees worldwide during the last century. Since 2007, when the first molecular evidence for the presence of CLas in North-West Frontier Province of Pakistan (Khyber Pakhtunkhwa) were presented, there have been a limited number of studies reporting the pathogen in different citrus growing districts of the Punjab Province, one of the major citrus producing areas of the country. In this study, a small-scale survey was conducted in citrus groves exhibiting HLB-like symptoms in different districts of Punjab Province. The aim was to obtain current information on the incidence of CLas in the area and complement the previous studies. Conventional and real time quantitative polymerase chain reaction (PCR and qPCR) assays were used for the detection of CLas in the 94 samples tested, followed by sequencing of the PCR amplicons. Overall CLas was detected in 43% (40/94) of the tested samples from Kinnow mandarin (n= 22), sweet orange (n= 12), grapefruit (n= 3) and Feutrell’s early mandarin (n= 3). In agreement with previous reports, this survey confirmed the presence of HLB in the Punjab Province of Pakistan and provided updated molecular evidence for the presence of CLas and disease incidence for four citrus cultivars from five citrus growing districts of the province.