Citrus variegated chlorosis (CVC) and coffee leaf scorch (CLS) are two economically important diseases in Brazil caused by the bacterium Xylella fastidiosa. Strains of the bacterium isolated from the two plant hosts are very closely related, and the two diseases share sharpshooter insect vectors. In order to determine if citrus strains of X. fastidiosa could infect coffee and induce CLS disease, plant inoculations were performed. Plants of coffee, Coffea arabica ‘Mundo Novo’, grafted on Coffea canephora var. robusta ‘Apuatão 2258’ were mechanically inoculated with triply cloned strains of X. fastidiosa isolated from diseased coffee and citrus. Three months postinoculation, 5 of the 10 plants inoculated with CLS-X. fastidiosa and 1 of the 10 plants inoculated with CVC-X. fastidiosa gave positive enzyme-linked immunosorbent assay (ELISA) and/or polymerase chain reaction (PCR). Eight months postinoculation, another six plants inoculated with CVC-X. fastidiosa gave positive PCR results. The two X. fastidiosa strains were isolated from the inoculated plants and showed the same characteristics as the original clones by microscopy, ELISA, and PCR. None of the plants inoculated with sterile periwinkle wilt (PW) medium as controls gave positive reactions in diagnostic tests, and none developed disease symptoms. Six months postinoculation, seven plants inoculated with CLS-X. fastidiosa and eight inoculated with CVC-X. fastidiosa began to develop characteristic CLS symptoms, including apical and marginal leaf scorch, defoliation, and reductions of internode length, leaf size, and plant height, terminal clusters of small chlorotic and deformed leaves, and lateral shoot dieback. We have demonstrated that X. fastidiosa from citrus plants is pathogenic for coffee plants. This has important consequences for the management of CLS disease and has implications for the origin of citrus variegated chlorosis disease.

Xylella fastidiosa causes citrus variegated chlorosis (CVC) disease in Brazil and Pierce's disease of grapevines in the United States. Both of these diseases cause significant production problems in the respective industries. The recent establishment of the glassy-winged sharpshooter in California has radically increased the threat posed by Pierce's disease to California viticulture. Populations of this insect reach very high levels in citrus groves in California and move from the orchards into the vineyards, where they acquire inoculum and spread Pierce's disease in the vineyards. Here we show that strains of X. fastidiosa isolated from diseased citrus and coffee in Brazil can incite symptoms of Pierce's disease after mechanical inoculation into seven commercial Vitis vinifera varieties grown in Brazil and California. Thus, any future introduction of the CVC strains of X. fastidiosa into the United States would pose a threat to both the sweet orange and grapevine industries. Previous work has clearly shown that the strains of X. fastidiosa isolated from Pierce's disease- and CVC-affected plants are the most distantly related of all strains in the diverse taxon X. fastidiosa. The ability of citrus strains of X. fastidiosa to incite disease in grapevine is therefore surprising and creates an experimental system with which to dissect mechanisms used by X. fastidiosa in plant colonization and disease development using the full genome sequence data that has recently become available for both the citrus and grapevine strains of this pathogen.

Xylella fastidiosa, a xylem-limited bacterium, causes several economically important diseases in North, Central, and South America. These diseases are transmitted by sharpshooter insects, contaminated budwood, and natural root-grafts. X. fastidiosa extensively colonizes the xylem vessels of susceptible plants. Citrus fruit have a well-developed vascular system, which is continuous with the vascular system of the plant. Citrus seeds develop very prominent vascular bundles, which are attached through ovular and seed bundles to the xylem system of the fruit. Sweet orange (Citrus sinensis) fruit of cvs. Pera, Natal, and Valencia with characteristic symptoms of citrus variegated chlorosis disease were collected for analysis. X. fastidiosa was detected by polymerase chain reaction (PCR) in all main fruit vascular bundles, as well as in the seed and in dissected seed parts. No visual abnormalities were observed in seeds infected with the bacterium. However, the embryos of the infected seeds weighed 25% less than those of healthy seeds, and their germination rate was lower than uninfected seeds. There were about 2,500 cells of X. fastidiosa per infected seed of sweet orange, as quantified using real-time PCR techniques. The identification of X. fastidiosa in the infected seeds was confirmed by cloning and sequencing the specific amplification product, obtained by standard PCR with specific primers. X. fastidiosa was also detected in and recovered from seedlings by isolation in vitro. Our results show that X. fastidiosa can infect and colonize fruit tissues including the seed. We also have shown that X. fastidiosa can be transmitted from seeds to seedlings of sweet orange. To our knowledge, this is the first report of the presence of X. fastidiosa in seeds and its transmission to seedlings.

O controle biológico de insetos vetores de Phyllocnistis citrella em citros tem se mostrado ineficiente e o uso de inseticidas apresenta poucas opções. O objetivo do trabalho foi avaliar a eficiência de inseticidas sistêmicos, aplicados via tronco, no controle de Oncometopia facialis (Signoret) (Hemiptera: Cicadellidae), Phyllocnistis citrella Staiton (Lepidoptera: Gracillaridae) e Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae) em citros. A eficiência para O. facialis foi determinada pelo método de confinamento, utilizando-se 5 cigarrinhas adultas por repetição. Para P. citrella avaliou-se o número de folhas com lagartas em 3 ramos/planta e para T. citricida o número de ramos infestados. O acefate Pellet 970, vamidotion CE 300, monocrotofós CE 400, acetamipride PM e SL, e imidaclopride SL, nas doses testadas, controlam O. facialis, mas com períodos residuais variando de 12 a 104 dias, sendo os mais eficientes acetamipride SL (1,0 g i.a. por planta) e imidaclopride (1,0 g i.a. por planta). Os inseticidas acefate, vamidotion, monocrotofós, acetamipride e imidaclopride foram eficientes no controle de T. citricida e de P. citrella, com exceção de acetamipride PM nas doses de 0,4 e 0,6 g i.a. por planta. Acetamipride e imidaclopride apresentaram período de controle para P. citrella superior a 42 dias.

Análise Faunística de Cicadelíneos (Hemiptera: Auchenorrhyncha, Cicadellidae) em Pomar de Laranjeira 'Westin' RESUMO -O objetivo deste trabalho foi analisar a fauna de cigarrinhas em pomar de laranjeira 'Westin' enxertada sobre limoeiro 'Cravo', em plantas com cinco anos de idade. Foram instaladas armadilhas adesivas amarelas na borda da mata, na periferia do talhão e no interior do talhão, sendo avaliadas quinzenalmente, por três anos. ABSTRACT -The purpose of this study was to analyze sharpshooter fauna in a fi ve-year-old 'Westin' sweet orange orchard. Yellow sticky traps were placed on the edge of a forest, and on the periphery and inside the citrus stand. The traps were evaluated fortnightly, for three years. The most frequent species were Acrogonia citrina Marucci & Cavichioli, Bucephalogonia xanthophis (Berg), and Oncometopia facialis (Signoret). B. xanthophis occurred more in the forest edge, especially on spring and winter. A. citrina occurred most frequently in the forest edge, especially on spring. The highest incidence of O. facialis was inside the citrus stand, on spring and summer. Other cicadellids occurred more often in the forest edge, especially on summer. A. citrina, B. xanthophis, Dilobopterus costalimai Young, and O. facialis were predominant in all places studied. A. citrina, B. xanthophis and O. facialis were super dominant, super abundant, super frequent, and constant, except inside the stand, where B. xanthophis was dominant, very abundant, very frequent, and constant. D. costalimai and Homalodisca ignorata Melichar were dominant, very abundant, and very frequent in the forest edge and in the periphery of the stand, and D. costalimai was also predominant inside the stand. Scopogonalia subolivacea (Stål) was predominant in the forest edge and inside the stand, while Plesiommata corniculata Young was predominant in the periphery (both were dominant, very abundant, very frequent, and accessory).