Wind dispersal of Puccinia psidii urediniospores and progress of eucalypt rust

Abstract

Summary To identify and implement Puccinia psidii control strategies, it is essential to understand the role of environmental factors on rust‐disease development and spread among eucalypt (Eucalyptus spp.) plantations. In this study, we evaluated the wind dispersal of P. psidii urediniospores and the progress of eucalypt rust in a field trial in Brazil. Urediniospores of P. psidii were trapped in a Burkard® spore trap from July 2004 to June 2005. To evaluate the progress of eucalypt rust, plots were established in March 2002 using a clonal hedge scheme. The incidence of both branches and leaves with rust was assessed weekly from February 2003 to October 2005. Disease progress was studied using time‐series analysis. Urediniospores were trapped on 77% of the days sampled. The highest average urediniospore concentration was detected from July to November, and most of the urediniospores (58%) were trapped at night. Urediniospore concentration was negatively correlated with rainfall, light intensity, minimum, average and maximum temperatures and wind speed, whereas urediniospore concentration was positively correlated with leaf‐wetness duration and relative humidity. From December 2004 to June 2005, average urediniospore concentration was 0.22 spores m−3 air h−1 and had no correlation with meteorological data. The highest average urediniospore concentration was associated with a combination of low average temperature, low light intensity, low wind speed, high relative humidity and high leaf wetness, which reflect conditions observed at night. The disease incidence was positively correlated with the urediniospores trapped at 12 days prior to disease assessment. According to the models obtained by the time series, a seasonal yearly effect was found on rust progress. Using our models, we were also able to forecast disease incidence up to 3 months after the last field assessment.

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

“…Additionally, the response curve of precipitation in the warmest quarter implied that excessive precipitation combined with high temperature decreased the probability of myrtle rust establishment. The negative effect of rain on establishment of myrtle rust was mentioned in previous studies, which suggested excessive rain would wash out the urediniospores (Dianese et al , ; Elith et al , ; Zauza et al , ).…”

“…In conclusion, the most accurate projection of myrtle rust is attained by combining the output of several models and using good quality input data. It is difficult to fully control this disease in natural habitats because the pathogen mostly spreads by wind (Zauza et al , ), but major efforts to limit its spread are warranted considering the potential economic, ecological and sociocultural impact of myrtle rust in New Zealand.…”

A unique genotype of the rust pathogen, Puccinia psidii, on Myrtaceae in South Africa

“…Puccinia psidii has been reported from more than 73 genera and 450 species of plants in the Myrtaceae (Pegg et al 2014b;Giblin and Carnegie 2014;Zauza et al 2015).…”

Timing of fungal spore release dictates survival during atmospheric transport

“…Often there are no obvious correlations. Despite a wealth of data describing different diurnal or nocturnal patterns of spore liberation and a nascent awareness of their significance for spore dispersal (21)(22)(23) the drivers of observed patterns remain obscure (13,16).…”