Climatic favourability zones for Eucalyptus rust in Brazil

Abstract

Brazilian forest-based industries are supported by more than 5.5 million hectares of Eucalyptus growing under different climatic conditions with different degrees of favourability for rust Puccinia psidii, including both traditional and expanding areas, where such disease is of major concern for the industry, foresters and scientists. The main objective of this study was to define favourable climatic zones for Eucalyptus rust in Brazil with the following aims: (i) to develop a spatial method for estimating the mean night-time temperature (T ng ); (ii) to assess and validate a Eucalyptus rust model;and (iii) to map Eucalyptus rust favourability zones in Brazil based on the proposed model. A straightforward method, based only on latitude, day of the year, maximum and minimum air temperatures, was developed to estimate T ng , which is a key variable for a proper application of Ruiz rust model. Based on 37 field experiments with natural rust occurrence, it was observed that climatic conditions are determining factors for disease severity. Significant correlations between disease severity observed in the field and climatic conditions were found: a negative correlation with temperature (r = .50, p < .01) and a positive correlation with relative humidity (r = .89, p < .0001). A significant correlation (r = .81, p < .0001) between the normalized infection index, produced from Ruiz model, and the average rust score was also observed. Once the model was validated under field conditions, it was applied using historical average data of air temperature and leaf wetness duration to obtain monthly Eucalyptus rust favourability maps for the whole country. These final maps show that favourable climatic zones for Eucalyptus rust are extremely dynamic, with high temporal and spatial variability in Brazil and that climatic conditions should be considered for expansion of Eucalyptus to new areas, in breeding programmes, and for defining the most suitable seasons for forest establishment in each climate of the country. These results provide forestry managers with practical tools to reduce uncertainty about the expected severity of Eucalyptus rust in Brazil.

Projecting the suitability of global and local habitats for myrtle rust (Austropuccinia psidii) using model consensus

“…Several prediction models are already available for myrtle rust, but all of them rely on a single modelling approach (Magarey et al , ; Kriticos & Leriche, ; Elith et al , ; Kriticos et al , ; Alvares et al , ; Stewart et al , ; Berthon et al , ). These individual models are associated with different sets of uncertainties in the predictions.…”

“…Nevertheless, MMF projected somewhat larger areas as suitable (in Brazil, China, central Africa and eastern Australia) than CLIMEX and MaxEnt. While MMF projected highly suitable areas in central and northwest Brazil, there are only a few reports of rust from these regions so far (Alvares et al , ). This might be due to a lack of host plants or extensive surveys because the area is not easily accessible.…”

“…Although, this model performed well for Australia, it did not predict Tasmania, where myrtle rust was reported in 2015, as suitable (Tobias et al , ). Alvares et al () developed a spatial regression model predicting myrtle rust in Brazil from calculated night temperatures and leaf wetness durations. Their model predicted a large area in central and northwest Brazil as highly suitable in most months of the year although only few reports of the rust are available from these regions to date.…”

Genetic diversity of the myrtle rust pathogen (Austropuccinia psidii) in the Americas and Hawaii: Global implications for invasive threat assessments

“…Because of the urgent need to better understand the invasive threat posed by A. psidii, several previous studies have used bioclimatic modelling to predict the potential geographic range of this pathogen (e.g., Alvares et al, 2017;Booth & Jovanovic, 2012;Booth, Old, & Jovanovic, 2000;Elith, Simpson, Hirsch, & Burgman, 2013;Glen et al, 2007;Kriticos & Leriche, 2008;Kriticos, Morin, Leriche, Anderson, & Caley, 2013;Magarey et al, 2007;Ramsfield, Dick, Bulman, & Ganley, 2010;Roux et al, 2015). Most of these previous risk assessments for A. psidii are directed at specific geographic regions and/or did not consider distinct genetic groups within A. psidii that may have different ecological behaviours or climatic requirements.…”

Influência da época de plantio no crescimento em altura e na intensidade da ferrugem em monoprogênies e clones de Eucalyptus urograndis

“…Para a seleção de material genético resistente à ferrugem, as condições ambientais regionais de cada local de seleção devem ser analisadas (SILVA et al, 2013), isto porque a zona climática favorável à ferrugem mostra-se dinâmica e com alta variabilidade temporal e espacial no Brasil (ALVARES et al, 2016). A ocorrência da doença é distribuída em função da favorabilidade climática por regiões e épocas do ano, o outono e verão são as mais favoráveis ao fungo (MORAES, 2013).…”