Melon fruit quality front mildew incidence and management of nitrogen and potassium topdressing

This work aimed to evaluate the application effect of different dosages of nitrogen and potassium topdressing on mildew severity and on yield and fruit quality of melon. The three cultivars, Jangada, Gaucho Casca de Carvalho and Gaucho Redondo Cone Sul were evaluated in Cerrado (savannah) and floodplain areas. At 34 days after sowing (DAS) the topdressing treatments with different dosages of nitrogen and potassium were applied. The mildew severity estimation started at 56 DAS and was performed in five-days intervals until the harvesting of the fruits. The yield and physicochemical characteristics of the collected fruits were evaluated at harvest. There was no significative interaction among nitrogen and potassium topdressing, the cultivars and cultivated areas. However, there was significative differences when the factors were analyzed in separate. The cultivar Gaucho Redondo Cone Sul showed a significant linear increase in the area under the disease progress curve and higher productivity on cerrado compared to the remaining cultivars. The cultivar Gaucho Casca de Carvalho produced heavier and with higher °Brix fruits on cerrado. It is possible to conclude that the applied topdressings did not reduce the mildew severity in all tested cultivars, but they increased the yield in the floodplain area without modifying the physicochemical characteristics of the pulp on the evaluated melon fruits.This work aimed to evaluate the application effect of different dosages of nitrogen and potassium topdressing on mildew severity and on yield and fruit quality of melon. The three cultivars, Jangada, Gaucho Casca de Carvalho and Gaucho Redondo Cone Sul were evaluated in Cerrado (savannah) and floodplain areas. At 34 days after sowing (DAS) the topdressing treatments with different dosages of nitrogen and potassium were applied. The mildew severity estimation started at 56 DAS and was performed in five-days intervals until the harvesting of the fruits. The yield and physicochemical characteristics of the collected fruits were evaluated at harvest. There was no significative interaction among nitrogen and potassium topdressing, the cultivars and cultivated areas. However, there was significative differences when the factors were analyzed in separate. The cultivar Gaucho Redondo Cone Sul showed a significant linear increase in the area under the disease progress curve and higher productivity on cerrado compared to the remaining cultivars. The cultivar Gaucho Casca de Carvalho produced heavier and with higher °Brix fruits on cerrado. It is possible to conclude that the applied topdressings did not reduce the mildew severity in all tested cultivars, but they increased the yield in the floodplain area without modifying the physicochemical characteristics of the pulp on the evaluated melon fruits

Avaliação da diversidade de plantas espontâneas e a densidade de ácaros predadores em cultivo de pinhão-manso.

A vegetação espontânea possui importantes funções ecológicas para os agroecossistemas, principalmente ligadas ao fornecimento de recursos para a manutenção dos inimigos naturais. O objetivo com este trabalho é avaliar a diversidade de plantas espontâneas e a distribuição temporal de ácaros predadores associados a cultura do pinhão-manso e às plantas espontâneas. Para tanto, em uma área de cultivo de pinhão-manso de 0,5 ha foram realizadas amostragens mensais, de fevereiro de 2010 a janeiro de 2011, de ácaros predadores tanto em plantas espontâneas quanto na cultura. Foram estimados o índice Shannon-Wiener (‘H) de diversidade para as plantas espontâneas. A diversidade de plantas pelo índice de Shannon-Wiener correlacionou-se significativamente com a densidade de ácaros predadores. Com isso, a diversidade de plantas espontânea influenciou diretamente a ocorrência de inimigos naturais no agroecossistema

Predação por coccinelídeos e crisopídeo influenciada pela teia de Tetranychus evansi

The aim of this work was to evaluate the effect of the webbing produced by Tetranychus evansi (Acari: Tetranychidae) on the predation efficiency of Cycloneda sanguinea and Eriopis connexa coccinellids and of the Chrysoperla externa chrysopid. The predation efficiency on T. evansi females with and without webbing on tomato leaf discs was evaluated for each juvenile stage of the different predator species tested. There was a negative effect of T. evansi webbing on the predation efficiency of the second and third C. externa juvenile stages. Regarding E. connexa, only the predation by the oldest juvenile stage was negatively affected by the webbing. The predation efficiency of the first and the third juvenile stages of C. sanguinea was lower in the presence of webbing, but the opposite was observed for the fourth stage. The defensive role of T. evansi webbing varies according to the predator species and their developmental stage.O objetivo deste trabalho foi avaliar o efeito da teia produzida por Tetranychus evansi (Acari: Tetranychidae) na eficiência de predação por coccinelídeos Cycloneda sanguinea e Eriopis connexa e pelo crisopídeo Chrysoperla externa. A eficiência em predar as fêmeas de T. evansi na presença e na ausência de sua teia em discos de folhas de tomateiro com ácaros foi avaliada para cada instar das diferentes espécies de predadores. Foi observado efeito negativo da teia produzida por T. evansi na eficiência de predação do segundo e do terceiro instar de C. externa. Quanto à E. connexa, somente a predação pelo último instar foi influenciada negativamente pela presença da teia. A predação pelas larvas de primeiro e terceiro instar de C. sanguinea foi significativamente menor na presença da teia; no entanto, o resultado foi contrário para o quarto instar. O efeito da teia de T. evansi como mecanismo de defesa varia conforme a espécie e o estágio de desenvolvimento do predador

Efeito de óleos vegetais na inibição do crescimento micelial de fungos fitopatogênicos

The use of vegetable compounds as an alternative for control phytopathogens has received prominence in research to enable sustainable management methods in agriculture. Fungi such as Didymella bryoniae, Pyricularia grisea, Rhizoctonia solani, and Sclerotium rolfsii are important for causing great losses in production. In this context, the purpose was to evaluate the fungitoxicity of plant oils in inhibiting themycelial growth of pathogenic fungi. The tests were conducted in completely randomized design with 13 treatments (Cymbopogon nardus, C. citratus, Lippia alba, Eugenia dysenterica, Caryocar brasiliense, Azadirachta indica, A. indica – commercial – Ageratumconyzoides, Jatropha curcas, Eucalyptus sp., Mentha piperita, Tiofanato metílico e Testemunha) and four replications. To evaluate the fungitoxicity were distributed, 1.5 μ L mL-1 of the treatment were distributed on the surface of PDA culture medium. The Eucalyptus sp., M. piperita, L. alba, C. nardus, and C. citratus essential oils inhibited the growth of the fungus P. grisea. D. bryoniae did not growth only in the treatment of C. citratus. The R. solani and S. rolfsii fungi did not show mycelial growth when subjected to treatments of M. piperita, L. alba, C. nardus, and C. citrates essential oils.O uso de compostos vegetais como alternativa para controle de fitopatógenos tem recebido destaque em pesquisas que visam viabilizar métodos de manejo sustentável na agricultura. Fungos como Didymella bryoniae, Pyricularia grisea, Rhizoctonia solani e Sclerotium rolfsii são importantes por causarem grandes perdas na produção. Neste contexto, objetivou-se avaliar a fungitoxicidade de óleos vegetais na inibição do crescimento de fungos fitopatogênicos. Os ensaios foram conduzidos em delineamento inteiramente casualizado com 13 tratamentos (Cymbopogon nardus, C. citratus, Lippia alba, Eugenia dysenterica, Caryocar brasiliense, Azadirachta indica, A. indica - comercial, Ageratum conyzoides, Jatropha curcas, Eucalyptus sp., Mentha piperita, Tiofanato metílico e Testemunha) e quatro repetições. Para a avaliação da fungitoxicidade, foram distribuídos 1,5μ L mL-1 dos tratamentos na superfície do meio de cultura BDA (batata-dextrose-ágar). Os óleos essenciais de Eucalyptus sp., M. piperita, L. alba, C. nardus e C. citratus inibiram o crescimento de P. grisea. D. bryoniae não apresentou crescimento micelial apenas no óleo de C. citratus. Os fungos R. solani e S. rolfsii não cresceram quando submetidos aos tratamentos de óleos essenciais de M. piperita, L. alba, C. nardus e C. citratus

Crestamento gomoso do caule da melancia: Etiologia, epidemiologia e medidas de controle

The stem gummy blight (Didymella bryoniae) is one of the most important fungal diseases of the crop of the watermelon, because it causes damping off of the seedlings, lesions on leaves and cotyledons, and formation of cankers on stems and stalks. The fungus survives in the absence of the host on or beneath the soil, in sick crop residues, in other cultivated curcubitáceas, weeds or seeds. To control the disease is recommended the adoption of integrated management techniques, including cultural practices, chemical control and genetic control with the use of tolerant and / or resistant genotypes and other measures. This review aims to address the information to organize knowledge obtained in national and international literature on the gummy stem blight in watermelon crop. We tried to relate the aspects of etiology, epidemiology and controlling measures of D. bryoniae. It was noted that after several studies had been conducted so far, you must search for further information about the biology of the pathogen and the management of the disease in the field.O crestamento gomoso do caule (Didymella bryoniae) é uma das doenças fúngicas mais importantes da cultura da melancia, pois causa tombamento das plântulas, lesões nas folhas e cotilédones, e formação de cancros no caule e nas hastes. O fungo sobrevive na ausência do hospedeiro sobre e/ou abaixo do solo, nos restos culturais doentes, em outras curcubitáceas cultivadas, plantas daninhas ou em sementes. Para o controle da doença recomenda-se a adoção de técnicas de manejo integrado, incluindo práticas culturais, controle químico e controle genético com a utilização de genótipos tolerantes e/ou resistentes, além de outras medidas. Esta revisão tem por objetivo abordar informações da literatura nacional e internacional sobre o crestamento gomoso do caule na cultura da melancia. Procurou-se relatar os aspectos de etiologia, epidemiologia e medidas de controle de D. bryoniae. Foi possível constatar que apesar de vários estudos terem sido realizados até o momento, deve-se buscar novas informações a respeito da biologia do patógeno bem como sobre o manejo da doença no campo

Glycerine associated molecules with herbicide for controlling Adenocalymma peregrinum in cultivated pastures

The weed Adenocalymma peregrinum that is popularly known in Brazil as “ciganinha”, belongs to the family Bignoniaceae. The only way to control this plant species in crop fields is by the application of herbicides on the stump or directly on the stem. The present study aimed to analyze the effect of glycerine in controlling A. peregrinum (MIERS) L.G.Lohmann when applied on the stem. The glycerin used as a spray application of herbicide, underwent pre-purification processes with different concentrations of phosphoric acid (85%) and was characterized for water content, sulphated ash, total glycerol, matter organic non-glycerol (MONG), methanol and pH. For the analysis of the chemical composition of the stem lignin, holocellulose, extractives, calorific value and elementary quantitative determination of C, N, H, S were determined, as well as the total content of oxygen from the stem. The field work was installed at the town of Alvorada-TO, following the randomized complete block design with six treatments and four replications. Results show that the stem of A. peregrinum contains a significant amount of nitrogen, compared to other species, and high lignin content which makes it the most resistant species. The use of glycerin combined to the herbicide (picloram and triclopyr), was not efficient when compared to diesel oil. It was observed that the glycerin has potential as a vehicle for applying herbicides, leaving much to the development of new studies to make changes in its physicalchemical characteristics.Key words: Weeds, pastures, management, Adenocalymma peregrinum

Biology and life table of the red spider mite Tetranychus bastosi on physic nut

O objetivo deste trabalho foi determinar a biologia e a tabela de vida de Tetranychus bastosi em pinhão‑manso (Jatropha curcas). O experimento foi realizado em ambiente controlado a 26ºC e 75% de UR, com fotófase de 12 horas. Os ovos usados nos experimentos foram oriundos de criação estoque. As avaliações foram realizadas duas vezes ao dia, para a biologia do ácaro, e uma vez, para os parâmetros reprodutivos. O ciclo médio de vida das fêmeas foi de 9,63 dias e o dos machos, de 8,94 dias. A razão sexual foi 0,65 e a longevidade média das fêmeas foi de 16 dias, com produção média de 59 ovos por fêmea. Os parâmetros de tabela de vida obtidos foram: taxa líquida de reprodução (Ro), 45,41 indivíduos; duração média das gerações (T), 12,66 dias; taxa intrínseca de crescimento (rm), 0,0538 fêmea por fêmea por dia; razão finita de aumento (λ), 1,023 fêmea por fêmea; e tempo para duplicação da população (TD), 3,15 dias. O ácaro T. bastosi desenvolvese bem e apresenta alto potencial reprodutivo sobre folhas de pinhão‑manso.The objective of this work was to determine the biology and life table of Tetranychus bastosi on physic nut (Jatropha curcas). The experiment was carried out under controlled conditions at 26ºC and 75% RH, with photophase of 12 hours. The eggs used in the experiments were obtained from stock culture. Evaluations were performed twice a day for the biology of the mite, and once a day for reproductive parameters. The average life cycle of females was 9.63 days and that of males was 8.94 days. The sex ratio was 0.65, and the mean longevity of females was 16 days, with average production of 59 eggs per female. The life table parameters obtained were: liquid reproduction rate (Ro), 45.41 individuals; average generation length (T), 12.66 days; intrinsic growth rate (rm), 0.0538 female per female per day; finite growth rate (λ), 1.023 female per female; and time required for doubling the population (TD), 3.15 days. The spider mite T. bastosi develops well and presents a high reproductive potential on leaves of physic nut

Acarofauna in physic nut culture and associated spontaneous weeds

O objetivo deste trabalho foi identificar ácaros na cultura de pinhão‑manso e em espécies de plantas espontâneas associadas. Para isso, foram avaliadas a riqueza e a abundância de ácaros em plantas de pinhão‑manso e em 14 espécies de plantas espontâneas associadas. As amostragens foram realizadas por meio de coletas mensais de folhas de plantas de pinhão‑manso e de plantas espontâneas, nas entrelinhas do cultivo. Foram encontradas quatro espécies de ácaros predadores – Amblyseius tamatavensis, Paraphytoseius multidentatus, Typhlodromalus aripo e Typhlodromalus clavicus –, com potencial para uso no controle biológico de ácaros‑praga na cultura do pinhão‑manso, e duas importantes espécies de ácaros fitófagos – Brevipalpus phoenicis e Tarsonemus confusus – desconhecidas como praga da cultura. Entre as plantas espontâneas avaliadas, quatro espécies – Hyptis suaveolens, Peltaea riedelii, Urochloa mutica e Andropogon gayanus – abrigam grande riqueza e abundância de ácaros predadores, enquanto oito destacaram-se pela diversidade de ácaros fitófagos.The objective of this work was to identify mites in physic nut culture, and in associated spontaneous weed species. For this, mite richness and abundance on physic nut plants and on 14 species of associated spontaneous weeds were evaluated. Samplings were done with monthy collections of leaves from physic nut plants and from weeds, between planting lines. Four species of predatory mites – Amblyseius tamatavensis, Paraphytoseius multidentatus, Typhlodromalus aripo and Typhlodromalus clavicus –, with potential for biological control of pest mites on physic nut culture, and two species of phytophagous mites – Brevipalpus phoenicis and Tarsonemus confusus –, not yet known as pests of the culture were found. Among the evaluated spontaneous weeds, four species – Hyptis suaveolens, Peltaea riedelii, Urochloa mutica and Andropogon gayanus – harbor great richness and abundance of predatory mites, whereas eight harbored a high diversity of phytophagous mites