A mancha marrom de altenária, ou MMA (Alternaria alternata), é a doença fúngica mais importante das tangerinas no mundo. Observações de campo revelaram a ocorrência de lesões de MMA em folhas feridas pela lagarta-minador-dos-citros (LMC). Assim, o objetivo deste estudo foi avaliar a relação entre a LMC e MMA. Folhas jovens de plantas de tangor Murcott e folhas destacadas de 16 diferentes variedades de tangerinas com e sem lesões, causadas por CLM, foram inoculadas com A. alternata. Os sintomas da MMA foram subsequentemente quantificados através da contagem do número de lesões, e a área da lesão foi estimada utilizando uma escala diagramática. A presença de danos da LMC agrava a severidade de Alternaria alternata nas variedades de tangerina suscetíveis.

Alternaria brown spot, or ABS (Alternaria alternata), is the most prevalent fungal disease of tangerines in the world. Field observations have revealed ABS lesions on leaves wounded by the citrus leaf miner (CLM). Thus, the objective of this study was to assess the relationship between CLM and ABS. Leaves from young Murcott tangor plants and detached leaves from 16 different varieties of tangerines with and without lesions caused by CLM were inoculated with A. alternata. The symptoms of the plants were subsequently quantified by counting the number of lesions, and the lesion area was estimated using a diagrammatic scale. The presence of CLM damage aggravates the severity of Alternaria alternata fungus infections in susceptible tangerine varieties.

Caused by Alternaria alternata, Alternaria brown spot (ABS) is a major fungal disease of mandarins in Brazil, causing serious losses in commercial orchards of Ponkan tangerine (Citrus reticulata Blanco) and Murcott tangor [C. sinensis (L.) Osbeck × C. reticulata Blanco]. The response of 31 accessions/genotypes of mandarins and their hybrids to A. alternata, was evaluated in São Paulo state, Brazil. The incidence and severity of the disease in fruit were evaluated in the field, using diagrammatic scale, four times during 2008 and 2009. Based on these data, the area under the disease progress curve (AUDPC) was calculated. In parallel, in vivo and in vitro inoculations with A. alternata were made on leaves to confirm field results. Resistance and susceptibility was evaluated in controlled experiments by counting the number of lesions per leaf using a diagrammatic scale. Most of the genotypes were symptomatic after inoculation with A. alternata with disease most severe on the hybrids Nova, África do Sul, Ponkan and Murcott. Cultivars like Cravo, Nules and Ortanique that have excellent fruit quality and had lower AUDPCs, whereas Fremont and Thomas were highly resistant to the fungus and did not show any symptoms in the field or in controlled inoculations. The attractiveness and pronounced flavor of Fremont and Thomas fruit make them new options for the citriculture.

O manejo das entrelinhas dos pomares de citros tem sofrido grandes alterações nos últimos anos. Dessa forma, este trabalho teve por objetivo avaliar influência da adubação verde de inverno e o uso de roçadoras laterais, na produção da laranjeira-'Pera'[Citrus sinensis (L.) Osbeck]. O ensaio foi conduzido em duas safras (2007/2008 e 2008/2009), em esquema de parcela subdividida, onde, nas parcelas, semearam-se três espécies de inverno (aveia-preta, tremoço e nabo forrageiro) e nas subparcelas utilizaram-se dois tipos de roçadoras laterais (convencional e "ecológica"). Vegetação espontânea e herbicida (glyphosate) em área total foram tratamentos de referência. No mês de julho (2007 e 2008), quantificaram-se a massa verde e a seca das vegetações intercalares e da projeção da copa, após roçagem. Para o cálculo da produção da laranjeira-'Pera', colheram-se os frutos das diferentes parcelas, efetuando-se as pesagens e, posteriormente, obtendo-se a eficiência de produção. Os tratamentos com adubo verde proporcionaram maior produção de massa verde e seca, e a utilização da roçadora "ecológica" lançou quantidade de material vegetal significativamente superior sob a copa das plantas de laranjeira-'Pera'. Nas duas safras, maior produção e eficiência de produção de frutos foi observada nas parcelas com uso da roçadora "ecológica". Quanto aos adubos verdes de inverno, apenas o tremoço incrementou a eficiência de produção em 2009. Conclui-se que o uso de roçadora "ecológica" incrementa a produção de laranjeira-'Pera'.

The inter-row management of citrus orchards has undergone major changes in recent years. Thus, this study aimed to evaluate the effect of winter cover crops and rotary mower in sweet orange 'Pêra' production. The experiment was conducted in two seasons (2007/2008 and 2008/2009), in a split plot design, where at the plots three species of winter cover crops (oat, lupine and radish) were sown in April and in sub-plots it was used two types of rotary mower (conventional and ecological). Natural vegetation (NV) and NV+herbicide (glyphosate) in the total area were the standard treatments of the experiment. In July (2007 and 2008) it was measured the mass of fresh and dry mass of each treatment and also after mowing. To calculate the production in August (2007 and 2008) the fruit were harvested and weighted and later it was obtained the efficiency of production. The treatments with winter cover crops showed greater production of fresh and dry mass and the use of ecological rotary mower released amount of plant material significantly higher under the canopy of sweet orange 'Pera' plants. In two seasons, higher production and efficiency of fruit production occurred in plots using the ecological rotary mower. Only lupines increased the efficiency of production of sweet orange 'Pêra' in 2009. Thus, it can be concluded that the use of ecological rotary mower increases the production of sweet orange 'Pera'.

A mancha preta dos citros (MPC), causada por Guignardia citricarpa Kiely, tem sido responsável por grandes prejuízos no Brasil, onde todas as variedades comerciais de laranjeira doce são suscetíveis. Tendo em vista as perdas econômicas que essa doença causa à citricultura brasileira, este trabalho teve como objetivo avaliar variedades de laranjeiras de maturação tardia quanto à suscetibilidade à MPC. Trinta e seis variedades foram avaliadas em dois anos (2007 e 2008), em Cordeirópolis (SP), e 35 em Conchal (SP), em experimentos utilizando-se delineamento de blocos casualizados, com três repetições. A severidade da MPC foi quantificada, entre os meses de junho a novembro (2007 e 2008), utilizando-se escala diagramática e, posteriormente, calculou-se a área abaixo da curva do progresso da doença. Todas as variedades foram suscetíveis à MPC, entretanto a Imperial e a Valência Pálida Israel mostraram menor suscetibilidade nos dois campos experimentais.

The citrus black spot - CBS (Guignardia citricarpa Kiely) has been responsible for great losses in Brazil, where all commercial varieties of sweet orange are susceptible. Given the economic losses that this disease causes to the brazilian citrus industry, this study aimed to evaluate the susceptibility of sweet orange varieties with late harvest to CBS. A total of 36 varieties were evaluated in Cordeirópolis city, and 35 located at Conchal city, in two years (2007 and 2008), both in São Paulo State, Brazil, in randomized block design assays with three replications. By using a diagrammatic scale specific to the CBS, the severity of CBS was quantified between the months from June to November (2007 and 2008), data was used to calculate the area under disease progress curve. All varieties were susceptible to CBS, however Imperial and Valência Pálida Israel were less susceptible than the others at both locations.