O Recôncavo da Bahia é uma região de clima propício à mancha graxa dos citros (Mycosphaerella citri), doença nunca antes estudada no Brasil. Os objetivos deste trabalho foram definir o tamanho mínimo de amostra para quantificar a incidência, caracterizar os sintomas da doença e elaborar uma escala diagramática para a avaliação de sua severidade. A partir de uma amostragem piloto realizada por avaliação de cinco folhas por quadrante, quatro quadrantes por planta e 30 plantas em cada um dos 10 pomares visitados no município de Cruz das Almas, foi determinado que o tamanho mínimo da amostra em quadrantes e folhas seria de quatro e 16 plantas, respectivamente. De 320 folhas coletadas de diferentes plantas em 11 pomares, foi constatada uma grande quantidade de lesões (média de 131) por folha sintomática, em sua maioria diminutas (média de 0,014cm²). A severidade variou de 0,15% a 35,85%, com média de 7,3%. Com base na severidade real em campo, foi elaborada uma escala diagramática com seis níveis: 1%, 2%, 5%, 9%, 18% e 36% de área foliar lesionada. Cinqüenta imagens de folhas foram submetidas a avaliadores por duas vezes, os quais estimaram a severidade com e sem a utilização da escala, constatando-se um discreto benefício no grau de precisão e de acurácia das estimativas com o uso da escala.

Brevipalpus phoenicis (Geijskes) is a cosmopolitan and polyphagous mite that transmits important phytoviruses, such as coffee ringspot virus, passion fruit green spot virus and Citrus leprosis virus C. To characterise the dynamics of the probability and the rate of B. phoenicis infestation in response to edaphic and climatic factors, monthly inspections were performed in nine orchards in a citrus region of the State of Bahia, Brazil, for 35 months. Three fruits per plant were examined using a magnifying glass (10×) on 21 plants distributed along a "W"-shaped path in each orchard. Meteorological data were collected from a conventional station. To determine the correlations among the climatic variables, the data were analysed using Spearman correlations. Variables were selected by principal component analysis, and those that contributed the most to differentiate the groups were evaluated via a Mann-Whitney test. Using the quantile-quantile method, the limit values for the following climatic variables were determined: temperature (24.5 °C), photoperiod (12 h), relative humidity (83%), evapotranspiration (71 mm) and rainy days (14 days). The combination of longer days, higher temperatures, lower relative humidity levels and lower evapotranspiration increased the probability of B. phoenicis infestation, whereas successive rain events decreased that risk. Infestation rates were negatively affected by relative humidity levels above 83% and were positively affected by a decreasing available soil-water fraction and increasing insolation and photoperiod.

Recorded in Brazil since 2004, Huanglongbing (HLB), or simply Greening, is the most impacting disease in citrus production worldwide. It induces qualitative and quantitative losses in production, but also can be lethal to the infected citrus plant. The disease is caused by phloem-limited bacteria with three identified species, Candidatus Liberibacter asiaticus (CLas), Ca. L. africanus (CLaf), and Ca. L. americanus (CLam). CLas and CLam are reported in Brazil, being vectored by the Asian citrus psyllid Diaphorina citri. HLB-infected citrus exhibit blotchy mottling with green islands on leaves, and small and lopsided fruits. As the infection progresses, excessive fruit drop and dead branches are frequently observed, shortening the trees' lifespan and reducing fruit yield and quality. HLB occurrence is restricted to the States of São Paulo, Minas Gerais, Mato Grosso do Sul and Paraná, which corresponds to more than 85% of citrus production in Brazil. Although citrus production is concentrated in these states, commercial citrus groves are present in 85% of the microregions of Brazil, reinforcing the economic and social importance of citrus for the country. Thus, in addition to the economic damage already caused to the national citrus industry, the spread of HLB to other regions of Brazil represents a great risk to the economic and food security of these non-affected regions. For this reason, the management of HLB is supported by legislative force, both at the federal and state levels. In 2008, based on scientific knowledge at the time, the Brazilian Ministry of Agriculture published a Normative Instruction 53 (IN53) which established criteria related to HLB surveillance and control, imposing the obligation to carry out periodic phytosanitary inspections, eradication of symptomatic hosts and planting HLB-free nursery trees. The implementation of IN53 has already resulted in the eradication of 55.5 million HLB-infected citrus plants in the State of São Paulo alone in the period from 2007 to 2019. In May 2021, IN53 was revoked and Portaria 317 was published. This new policy establishes the National Programme for HLB Prevention and Control. It addresses the problem according to the HLB status in each State, with or without the disease, and sets the general guidelines for local control actions.<br/> In view of the economic importance and complexity of this pathosystem, the disease has required concerted mobilization of the research community and inter-institutional cooperation, which has been working intensively to understand all the components directly and indirectly involved with the pathosystem. Also, a major cooperation effort is needed to gather all the information to develop and/or improve technologies and cultural practices to fight the disease better and reduce its impacts as much as possible. Here we present some of these efforts which are being carried out to develop short, medium and long term solutions for HLB control and management in areas of occurrence, as well as for surveillance and risk mitigation in non-affected areas.

RESUMO-Em duas regiões da Bahia -Litoral Norte (LN) e Recôncavo Baiano (RB) quantificaram-se a dinâmica espaço-temporal da infestação de plantas cítricas pelo ácaro Brevipalpus phoenicis. Dez pomares de cada região foram avaliados mensalmente (de abril de 2008 a fevereiro de 2011), nos quais 21 plantas tiveram três frutos/planta vistoriados com lupa de 10x para registrar a presença ou ausência do ácaro. A proporção média de plantas infestadas variou entre 0,38 e 1,0. Em frutos, a proporção mínima de infestação foi 0,10 e máxima de 0,73 no LN e 0,66 no RB. O processo de infestação foi sazonal, com mais unidades infestadas na primavera-verão (Nemenyi, p<0,05). A análise de densidade espectral mostrou a ocorrência de dois tipos de ciclos: um com período aproximado de 2 meses, possivelmente relacionado com a biologia do ácaro e outro anual, decorrente da interação vetor-hospedeiro-ambiente. Em ambas as regiões, a aleatoriedade caracterizou o padrão espacial da infestação do ácaro intra e interpomares. Não foram observados sintomas de leprose dos citros no RB. Termos para indexação: vetor do VLCi, padrão espacial, sazonalidade da infestação. INFESTATION DYNAMICS OF Brevipalpus phoenicis (GEIJSKES, 1939) (ACARI:TENUIPALPIDAE) IN CITRUS ORCHARDS IN BAHIA, BRAZILABSTRACT -The spatio-temporal dynamics of Brevipalpus phoenicis infestation was quantified in two regions of the state of Bahia, Brazil (North Coast-NC and Recôncavo Baiano-RB). In each region, 10 orchards were evaluated monthly (from April 2008 to February 2011), in which 21 plants had inspected three fruits per plant with a magnifying lens (10x) to record the presence or absence of the mite. The average proportion of infested plants varied between 0.38 and 1.0. In fruits, the minimum proportion of infestation was 0.10 and maximum, of 0.73 for NC and 0.66 in the RB. The infestation process had a strong seasonal component with more infested units detected in spring or summer (Nemenyi, p <0.05). The spectral density analysis showed the occurrence of two cycles of infestation: one of 2 to 3 months, possibly related to the mite´s biology and other larger, annual, arising from the interaction vector-host-environment. In both regions the spatial pattern of mite infestation within and between orchards was random. No symptoms of citrus leprosies were found in RB.

Huanglongbing (HLB) is one of the most devastating diseases for citrus sector. In Brazil, the state of Bahia is free of the disease, however it is on constant alert to prevent its introduction. One of the main areas of citrus exploitation in the state is located in the Recôncavo Baiano’s identity territory and is characterized by family-based production. This study aimed to perform a participative phytosanitary diagnosis with citrus growers from the “Recôncavo Baiano” region, recording their perception regarding the HLB and its vector, Diaphorina citri. The diagnosis, which featured 109 interviews, was carried out in five prominent cities in citrus production (Cruz das Almas, Governador Mangabeira, Muritiba, Santo Antônio de Jesus and São Felipe). The results showed that 70% of citrus growers never heard of the disease. It also indicated that only 6% of farmers have technical assistance. Even with the tradition of citrus farmers, the use of technologies is still limited. The presented results constitute an important tool for phytosanitary defense, as it provides strategic information that enable the planning of indispensable actions for preventing HLB entry in this territory, and also to minimize its negative impacts, contributing with the maintenance of the citrus production chain.