RESUMO A ferrugem, causada por Olivea neotectonae, destaca-se como principal doença da teca, causando desfolha prematura em todos os estádios fenológicos da cultura. O objetivo do estudo foi avaliar o progresso temporal da ferrugem em plantas adultas de teca no sul do Estado do Tocantins. Avaliaram-se a incidência e severidade da ferrugem (escala de notas) e obtiveram-se curvas de progresso da doença, que foram ajustadas aos modelos matemáticos monomolecular, logístico e Gompertz. Correlacionaram-se os dados de incidência e severidade com as variáveis climáticas coletadas na estação meteorológica, localizada na região do estudo. A incidência da ferrugem atingiu 100% aos 98 dias a partir do início das avaliações (DIA). A maior severidade (igual ou acima de 75%) foi observada aos 147 DIA. Houve correlação negativa e significativa entre severidade e temperatura mínima. O ajuste ao modelo de Gompertz sugere que medidas de controle devem ser tomadas objetivando reduzir a taxa de progresso da doença.

ABSTRACT Rust, caused by Olivea neotectonae, stands out as the main teak disease, causing premature defoliation regardless of the tree’s growth stage. In this study, we aimed to assess the temporal progress of rust in adult teak plants in southern Tocantins State (Brazil). Both rust incidence and severity were evaluated and the disease progress curves were obtained, adjusting to monomolecular, logistic and Gompertz mathematical models. Data from incidence and severity were correlated with climate variables collected by the agrometeorological station located in the study area. Rust incidence reached 100% at 98 days after beginning of the evaluations (DBE). The highest severity (equal or above 75%) was observed at 147 DBE. There was a significant and negative correlation between severity and minimum temperature. The adjustment of the Gompertz model suggests that control measures should be aimed primarily to reduce the rate of disease progress.

Thermal and spectroscopic analyses of essential oil extracted from Siparuna guianensis Aublet, an aromatic plant belonging to medicinal ethnobotany family Siparunaceae, were carried out. The plant is known throughout the North and Northeast of Brazil by the name negramina and has wide application as a natural insect repellent. Thermogravimetric analyses were correlated with the Arrhenius Equation to provide kinetic parameters of evaporation, including activation energy and frequency factor. Differential scanning calorimetric analysis showed the presence of an exothermic oxidation peak, probably as a result of transformations and decomposition of the solid structure before melting.