João Batista Vida

Manejo de doenças de plantas em cultivo protegido

Plant disease management in greenhouse crops Crop production based on plasticulture has allowed substantial gains in yields for many horticultural crops. In the greenhouse, crop production may be more easily optimized and plants may be better exploited for their maximum yields. However, this may increase the impact of some biotic and abiotic diseases. Less important diseases may become highly destructive in crops cultivated in the greenhouse. Indeed, in some cases disease management may become more complex in the greenhouse than in the field. Disease management in greenhouse cropping systems requires flexibility and great efforts for integration of available control measures.

Grape rust caused by Phakopsora euvitis, a new disease for Brazil

A ferrugem da videira foi constatada pela primeira vez no Brasil, ocorrendo em parreirais (Vitis spp.)comerciais no estado do Parana tendo recentemente atingido tambem o Estado de Sao Paulo. O fungo Phakopsora euvitis foi identificado como o agente causal da doenca. Esta ferrugem ocorre preferencialmente em folhas maduras causando a desfolha precoce das plantas infetadas.

Diagrammatic scale for assessment of grapevine rust

A diagrammatic scale with six levels of disease severity (1, 5, 12, 25, 50 and 75%) was developed to assess grapevine (Vitis spp.) rust severity, caused by the fungus Phakopsora euvitis. Two versions of the scale, in black-and-white and in color, were validated by seven raters without previous experience with grapevine rust, who estimated the severity of 30 grapevine leaves showing rust symptoms, with and without the use of the scales. Precision and accuracy were determined by linear regression, relating the assessments using the scales to actual severity. Actual severity was assessed with the software ASSESS®. Using the diagrammatic scales, some raters were able to improve precision and accuracy. The color scale provided slightly more precise and accurate estimates than the black-and-white scale.

Detection and identification of TMV infecting tomato under protected cultivation in Paraná State

During an inspection in plastic houses in Sapopema, Parana, 90% of tomato plants showed leaf abnormalities, probably associated with herbicide toxity. However, virus like symptoms developed in selected hosts after mechanical inoculatation. RT-PCR reactions using primers for an internal region within the movement protein gene of TMV and ToMV resulted in the amplification of a 409 bp cDNA fragment only by TMV primers. Deduced amino acids showed 100% identity when compared to TMV movement protein and 94% with ToMV. The RT-PCR protocol was efficient for quick and conclusive determination of virus species. The virus was purified and a polyclonal antiserum was raised for future surveys in tomato crops of Parana. The partial genomic sequence obtained for TMV-Sapopema has been deposited under the accession number DQ173945, which is the first partial genomic sequence of an isolate of TMV from Brazil in the GenBank, and the first tomato virus isolate from Parana to have some of its biological and molecular properties determined.

Caracterização morfológica e identificação molecular de isolados de Fusarium graminearum associados à giberela do trigo e triticale no sul do Brasil

Fusarium head blight (FHB) or scab is an important disease of wheat and triticale in Southern Brazil. The fungus Fusarium graminearum has been reported as the causal agent of this disease in Brazil even though other Fusarium species are also associated to FHB in other regions of the world. The aim of this study was to identify species of Fusarium associated with FHB on wheat and triticale in Southern Brazil. The identification was based on morphological features, and uppon polymerase chain reaction using species specific primers. The pathogenicity of the isolates in wheat was evaluated after inoculation of ears under greenhouse conditions. The twenty single spores isolates obtained from diseased ears and seeds were classified as F. graminearum.

Resistência de genótipos de videira à ferrugem

O objetivo deste trabalho foi avaliar a resistencia a ferrugem causada pelo fungo Phakopsora euvitis, em genotipos de videira, e a efi ciencia da infeccao de acordo com a idade das folhas e concentracao de inoculo. A avaliacao foi feita em 15 genotipos, com base nos seguintes componentes de resistencia: numero de pustulas (uredios) por cm2; tamanho das pustulas; numero de esporos produzidos por pustula; e periodo latente. Os componentes de resistencia, com excecao do periodo latente, apresentaram grande variacao quantitativa. A analise multivariada desses componentes diferenciou cinco grupos de genotipos. Os genotipos mais resistentes foram as cultivares porta-enxertos IAC313, IAC572 e IAC766, em que a efi ciencia da infeccao foi baixa, com pustulas menores e menor producao de urediniosporos, alem de reacao de hipersensibilidade no tecido em torno das pustulas. O grau de infeccao aumenta com o aumento na concentracao do inoculo. A ferrugem coloniza, indiscriminadamente, folhas jovens e folhas maduras de videira.

Patogenicidade de isolados de Corynespora cassiicola a diferentes espécies de plantas

Corynespora cassiicola, causes target leaf spot on a wide host range, including several economically important crops. This study investigated the pathogenicity of 15 C. cassiicola isolates on several hosts, in greenhouse. The fungal isolates were collected from several hosts. These isolates were inoculated on 12 different plant species. The isolates from cucumber showed the widest host range, infecting also six other hosts. The isolates from C. benghalensis and lettuce showed the narrowest host range, since they infected their host of origin and only another host plant. Most of the isolates lacked host specificity. Papaya plant, which showed the greatest susceptibility to the C. cassiicola isolates, were colonized by 12 of the 15 isolates tested. On the opposite, Vernonia sp. and C benghalensis were susceptible to only two and three C. cassiicola isolates, respectively.

Primeira ocorrência de ferrugem em capim-limão causada por Puccinia cymbopogonis no Brasil

It is reported the first occurrence of the lemongrass (Cymbopogon citratus (DC.) Stapf) rust fungi caused by Puccinia cymbopogonis Mass. in Brazil, State of Parana.

Efeito da temperatura e da luz na germinação de urediniósporos de Phakopsora euvitis.

ABSTRACT The objectives of this research were to analyze the effect oftemperature and light on in vitro germination of Phakopsora euvitis urediniospores, as well as the viability of urediniospores stored underdifferent temperatures. For determined the incubation period wasevaluate the germination of urediniospores in water-agar 2%, for 2,4, 6, 8, 10, 12 e 24 h. In order to evaluate the effect of temperatureand light in germination, uredinio spores in a suspension onto petri dishes were kept at 15, 20, 25 and 30 °C for 24 h, in the dark andunder continuous light. For the viability study, urediniospores were Angelotti, F.; Tessmann, D.J.; Scapin, C.R.; Vida, J.B. Effect of temperature and light on germination of uredinispores of Phakopsora euvitis . Summa Phytopathologica, v.37, n.1, p.59-61, 2011. armazenados em tubos Eppendorf foram mantidos nas temperaturas de –20±2, 5±2, 23±2 e 33±2 o C, no escuro. Verificou-se o aumento continuona germinacao dos esporos entre as avaliacoes com 6 a 24 horas deincubacao. As temperaturas cardinais (minima, otima e maxima) para agerminacao de urediniosporos

Variabilidade patogênica e efeito de carboidratos no crescimento micelial, esporulação e agressividade de Colletotrichum gloeosporioides da pupunheira

The aggressiveness of 17 Colletotrichum gloeosporioides isolates associated with anthracnose on leaves of peach palm (Bactris gasiapes) from Northern, Southeastern and Southern States of Brazil was evaluated through a bioassay using detached leaves of peach palm, at three stages: young, intermediate and fully expanded leaves. Differences on aggressiveness among isolates were significant only on fully expanded and intermediate leaves. Different sources of carbohydrates such as glucose, maltose and starch, added to potato-agar medium affected mycelial growth and sporulation of some isolates. Among five isolates tested, only two had their aggressiveness increased when conidia were produced on potato-agar medium supplemented with starch.