Huanglongbing (ex-greening) disease is one of the most serious diseases of citrus. It is caused by the phloem-limited, gram-negative bacterium “Candidatus Liberibacter spp.”. This bacterium is not well characterized mainly because it is still uncultured. There are two known strains, Asian (“Candidatus Liberibacter asiaticus”) and African (“Candidatus Liberibacter africanus”) that cause severe damage to citrus plants including twig dieback, decline, and death. Symptoms first appear as leaf mottling and chlorosis occurring in one shoot or sector of trees. Later, leaf symptoms resemble nutritional deficiencies (Zn, Ca, and N) that vary depending on the strains, with more severe symptoms caused by “Ca. L. asiaticus”. The Asian strains are transmitted by the Asian citrus psyllid (AsCP), Diaphorina citri, which is present in Brazil. The bacterium has been detected in citrus plants in many geographic locations including China, Japan, Thailand, India, the Philippines, the Arabian Peninsula, and Africa. In 2004, plants showing Huanglongbing symptoms were observed in the Araraquara County, a central region of the State of Sao Paulo, the largest citrus-producing area in Brazil. To verify the presence of “Ca. L. spp.” in these plants, leaf samples of sweet orange cvs. Hamlin and Valencia were used for DNA extraction and polymerase chain reaction amplification using the specific OI1 and Oi2c primers (1). Amplification of the 16S rDNA was positive for 2 (cvs. Hamlin and Valencia) of 10 analyzed plants. The amplified fragments were cloned and sequenced. The amplicons obtained from both plants showed the same sequence, which differed from “Ca. L. africanus”, utilized as the positive control in the amplification experiment (27 divergent bases in 1,160). The sequences were used for BLAST searches, and the results showed identities ranging from 94.71 to 100% with “Ca. L. spp.” sequences available at the National Center for Biotechnology Information database (on-line publication). The highest scores were obtained with “Ca. L. asiaticus sequences. These analyses confirmed the presence of such agent in the State of Sao Paulo. To our knowledge, this is the first report of “Ca. L. asiaticus” in Brazil as well as elsewhere in the Americas. The significance of this report relates to the potential damage that this pathogen could cause to the citrus industry in the largest citrus-producing country in the world. It remains unclear how and when the pathogen entered Brazil. Reference: (1) S. Jagoueix et al. Mol. Cell Probes 10:43, 1996.

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RESUMO -O quadro varietal das tangerinas plantadas comercialmente é bastante restrito, concentrando-se na tangerina 'Ponkan' e no tangor 'Murcott'. Aumentar o número de variedades, assim como ampliar o período de safra são fatores importantes tendo em vista que trarão vantagens ao consumidor e ao produtor desse grupo de citros. No período de 2002 a 2005, foram estudadas as características da variedade Fremont e comparadas com as tangerinas 'Ponkan' e 'Clementina Nules', no município de Capão Bonito-SP. Pode-se concluir, dos resultados obtidos, que as plantas da tangerina Fremont são de porte reduzido (semi-anãs); os frutos apresentam características excepcionais para consumo in natura, maturação de meia-estação e período de colheita, que se estende por até três meses, sendo dessa maneira boa opção para plantios visando à entressafra da 'Ponkan'. Termos para indexação: fruta fresca, qualidade, seleção, mercado, híbrido. By the results, it was possible to conclude that Fremont trees were semi-dwarfed, the fruits had excellent characteristics for in natura consumption and a harvesting season enlargement of three months, therefore appearing to be a good alternative for orchards, aiming at Ponkan' off-season period. CHARACTERISTICS OF FREMONT VARIETY COMPARED TO PONKAN AND CLEMENTINA NULES TANGERINES ABSTRACT -

A produção de tangerinas alcança expressão econômica em alguns estados brasileiros, principalmente em São Paulo, Paraná, Rio Grande do Sul e Minas Gerais. Nos últimos anos, um interesse crescente pelas mexericas tem sido observado no estado de São Paulo, possivelmente pela inviabilidade econômica de manterem-se pomares das principais variedades comerciais para frutos de mesa, tangerina Ponkan e tangor Murcott, devido à alta suscetibilidade à mancha marrom de alternária (MMA). O objetivo deste trabalho foi caracterizar 33 acessos de mexericas do Banco Ativo de Germoplasma de Citros do Instituto Agronômico de Campinas (BAG Citros IAC), visando selecionar variedades com boas características físico-químicas como massa, altura e largura de frutos, cor da casca, rendimento de suco, acidez, sólidos solúveis e Ratio e resistência à MMA para que possam ser comercializadas em outros períodos do ano, em comparação com a variedade mexerica Rio IAC 194, padrão desse grupo, cuja maturação é de meia-estação. Os resultados demonstraram que cerca de 85% dos acessos de mexerica avaliados em campo e in vitro apresentaram resistência à MMA. Selecionaram-se cinco acessos precoces e 11 mais tardios que a Rio IAC 194 como boas alternativas para a ampliação do período de safra de mexericas no estado de São Paulo. Palavras-chave: Citrus deliciosa, Alternaria alternata, resistência a doenças.Evaluation of willowleaf mandarin germplasm with respect to characteristics physical, chemical and susceptibility for alternaria brown spot AbstractThe mandarin production achieves economic expression in some Brazilian states, mainly in São Paulo, Paraná, Rio Grande do Sul and Minas Gerais. In recent years a growing interest in these mandarins has been observed in São Paulo, possibly due to the economic viability of maintaining the orchards of the main commercial varieties, Ponkan mandarin and Murcott tangor, due to high susceptibility to alternaria brown spot (ABS). The objective of this study was to characterize 33 accessions of willowleaf mandarins to 'Banco Ativo de Germoplasma de Citros' of the Instituto Agronômico de Campinas ('BAG Citrus IAC'), to select varieties with good horticultural characteristics as mass, height and width of fruit, skin color, juice content, acidity, soluble solids and Ratio, and tolerance to ABS and that can be marketed in other periods of the year in comparison with the Rio IAC 194 mandarin, standard variety -which ripening is half station. The results showed that to about 85% of the mandarin accessions evaluated in the field and in vitro were resistant to ABS. Was selected five hits early and later eleven more than Rio IAC 194, which can be good alternatives for the extension of the period of harvest of mandarins in the State of Sao Paulo.

Foi monitorado o comportamento de 16 porta-enxertos para o tangor Murcott [Citrus reticulata Blanco x C. sinensis (L.) Osbeck], do clone nucelar J, em experimento instalado em 1990, na Fazenda Raio de Sol, Itirapina-SP. Os porta-enxertos foram: tangelo 'Orlando' (C. reticulata Blanco x C. paradisi Macf.), laranja 'Caipira DAC' [C. sinensis (L.) Osbeck], limão 'Cravo'(C. limonia Osbeck), os trifoliatas 'Kryder 8-5'e 'EEL'[Poncirus trifoliata (L.) Raf.] e as tangerinas 'Cleópatra' (C. reshni hort. ex. Tanaka), 'Sunki' [C. sunki (Hayata) hort. ex. Tanaka], 'Batangas', 'Oneco', 'Swatow', 'Szinkon', 'Satsuma', 'Cravo', 'Dancy', 'Suen Kat' e 'Pook Ling Ming' (C. reticulata Blanco). As produções foram avaliadas de 1996 a 2003 e as maiores médias foram proporcionadas pelas plantas enxertadas nas tangerinas 'Cleópatra', 'Suen Kat', 'Pook Ling Ming' e 'Sunki' (>40 kg planta-1). Dentre os porta-enxetos que induziram as mais baixas produções, estão os dois trifoliatas, a 'Caipira DAC' e a tangerina 'Cravo' (<25 kg planta-1). As características de qualidade apresentadas pelos frutos, referentes aos anos de 1998 e 2002, indicaram não existir diferenças expressivas entre os tratamentos.