Domingos Eduardo Guimarães Tavares de Andrade

Elaboração e validação de escala diagramática para a cercosporiose do pimentão

Cercospora leaf spot of sweet pepper caused by the fungus Cercospora capsici is an important disease occurring in tropical conditions. Due to the inexistence of standard methods to quantify this disease in field conditions, a diagrammatic key including the levels 1.5, 3.5, 8.0,16.5, 31.0 and 50.0% of diseased leaf area was elaborated and tested for accuracy, precision and reproducibility to estimate Cercospora leaf spot severity without and with using the key. The diagrammatic key was validated by 13 raters with and without using the key, using 50 leaves with different levels of severity previously measured by the software AutoCAD®. Two evaluations were performed with the key at 7-day intervals when the same raters visually estimated different sequences of the same leaves. The accuracy and precision of each rater were determined by simple linear regression between actual and estimated severity. Without the key, eight raters overestimated disease severity. With the key raters obtained better levels of accuracy and precision, however four of them tended to overestimate the severity with absolute errors concentrated below 10%. Raters had good repeatability and high reproducibility in estimating disease severity by using the key when it was not used. The proposed diagrammatic key is suitable for evaluation of sweet pepper Cercospora leaf spot severity.

Elaboração e validação de escala diagramática para avaliação da severidade do carvão da folha do caupi

The leaf smut, caused by the fungus Entyloma vignae, is a common disease of cowpea in the Brazilian Northeast. Considering the inexistence of standard methods for assessment of this disease, a diagrammatic key was developed with 1.5, 3.5, 7.0, 14.5, 27.0 and 45.0% of diseased leaf areas and tested for accuracy, precision and reproducibility of the estimatives of leaf smut severity with and without using the key. The diagrammatic key was validated by 10 raters, with and without the key, using 48 cowpea leaflets with different levels of severity previously measured by the software AutoCAD® for Windows. Two evaluations were performed with the diagrammatic key at 7-day interval where different sequences of the same leaves were visually estimated by the same raters. The accuracy and precision of each rater were determined by simple linear regression between actual, evaluated electronically, and estimated severity. Without the diagrammatic key most of raters overestimated disease severity. With the key raters obtained better levels of accuracy and precision, with absolute errors concentrated around 10%. Raters showed good repeatability (90%) and reproducibility (84%) of estimative by using the key. The proposed diagrammatic key was suitable for the evaluation of severity of leaf smut on cowpea.

Doenças fúngicas em cultivos de plantas ornamentais temperadas da região Agreste do Estado de Pernambuco, Brasil

This study aimed to evaluate genetic variability using the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) and the phylogeny of five Beauveria bassiana: IPA145, IPA148, IPA223, IPA225 and IPA226, obtained from different hosts and geographical origin from the Biological Control Laboratory of the Agronomic Institute of Pernambuco - IPA. The ITS region was amplified using primers ITS1 and ITS4, where an amplicon with average size of 800 bp was observed and sequenced. The DNA sequences of Beauveria isolates were compared with sequences in the database (GenBank). The results show that all isolates, except IPA145, were presented as a monophyletic group. IPA145 showed a genetic identity of 99% with Cordyceps bassiana and B. bassiana. IPA148 was the most genetically distant from the others, with less than 40% similarity. Most of the Beauveria isolates studied proved to be phylogenetically distinct.

Differentiation of Colletotrichum gloeosporioides isolates by using total proteins and esterase electrophoretic patterns and extracellular enzymes production.

Isolados de Colletotrichum gloeosporioides (ISO-1, ISO-2, ISO-3, ISO-4, ISO-5 e ISO-6), agente causal da antracnose em frutos de mangueira, foram caracterizados por meio de padroes eletroforeticos de proteinas totais e esterase, em gel de poliacrilamida e producao de enzimas extracelulares, em substratos solidos especificos. A analise eletroforetica mostrou variacao no numero, intensidade de coloracao e posicao das bandas no gel, dentro dos dois sistemas estudados. Verificou-se polimorfismo em relacao a esterase, mostrando maior diferenca entre os isolados, enquanto que nas proteinas totais, observou-se comportamento aparentemente uniforme. Quanto a producao de enzimas extracelulares: amilase, lipase e protease, todos os isolados, embora variando em comportamento, apresentaram atividade para essas enzimas, sendo aparentemente mais acentuada a atividade proteolitica.