Watermelon (Citrullus lanatus) cultivated in almost all tropical and subtropical regions of the world, has its largest output in China, and then, according to FAO data, Turkey, Iran and Brazil, being one of the main crops cultivated in State of Tocantins, Brazil. In this work was investigated the occurrence and distribution of the watermelon viruses, totaling 752 samples taken in a stratified experimental design in four representative regions of production: Gurupi (150), Lagoa da Confusao (232), Formoso do Araguaia (265) and Porto Nacional (105). The sampling and collecting the leaves of plants with the presence of symptoms were performed once a week during the entire cultivation cycle. As a result, were observed by Dot-ELISA method, different types of viruses, such as Papaya ringspot W (PRSV-W), Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV) (potyvirus), Cucumber mosaic virus ( CMV) (Cucumovirus) and Zucchini lethal chlorosis virus (ZLCV) (Tospovirus). Of these, PRSV-W was predominant (22%), followed by WMV (15%), ZLCV (11%), CMV (5%) and ZYMV (4%). Mixed infections with PRSV-W + WMV and PRSV-W + ZLCV were also observed around 20% frequency (expressed with symptoms differently from a single infection). The results provide important support for the program management viruses.

Com o objetivo de avaliar o efeito da aplicação de húmus de minhoca e de esterco de gado na concentração foliar de nutrientes e na produção de manga 'Tommy Atkins', conduziu-se um experimento na empresa Meta Export Agrícola Ltda, no período de 1996 a 1999. Os tratamentos resultaram da combinação fatorial de três fontes (húmus de minhoca - HM, esterco de gado - EG e mistura de HM + EG) e cinco doses de matéria orgânica (0;20; 40; 60 e 80 dm³/planta). Os tratamentos foram aplicados, anualmente, no mês de janeiro, e as avaliações foram realizadas nas safras de 1997, 1998 e 1999. Não houve efeito dos tratamentos sobre a concentração foliar de nutrientes. Os teores de nitrogênio nas folhas mostraram-se bastante elevados, e a concentração de cálcio apresentou-se muito baixa. Não houve diferença entre as fontes, nem entre as doses de matéria orgânica durante o período de estudo. Houve um crescimento na produção ao longo das safras, devido ao aumento na idade das plantas.

Concurrent studies on the benefits of earthworm excrements and of cattle manure on leaf nutrient concentration and on the production of mango (Mangifera indica), variety Tommy Atkins, were conducted at Meta Export Agrícola Ltda, from 1996 to 1999. The treatments consisted of a factorial combination among three sources (earthworm excrements -- HM, cattle manure -- EG and a mixture of HM + EG) and five levels of organic matter (0, 20, 40, 60 and 80 dm³/plant). The treatments were applied annually always in January. The evaluations were carried out on growing season of 1997, 1998 and 1999. There was no effect of treatments on leaf nutrient concentration. The traits of nitrogen in the leaves were high and the concentration of calcium was low. There was neither difference among sources, nor among the levels of organic matter in the three years of study. There was an increase in production in all growing seasons, because of plant age.