Influence of low temperature and frost duration on Phytophthora alni subsp. alni viability

K Černý,V Strnadová,N Filipová

doi:10.5424/fs/2012212-02250

Abstract

Limits on the survival of P. alni subsp. alni (PAA) due to low temperature can be expected based on previously published laboratory and field studies. This study presents a laboratory experiment to test the influence of low temperature and frost duration on PAA viability. Ten PAA isolates were incubated at different temperatures (–0.1, –2.5, –5.0, –7.5, and –10.0 °C) and frost durations (0 – 7, 14, 21, and 28 days). A regression analysis confirmed the significant influence of both factors (low temperature and frost duration, and their interaction) on the survival of the pathogen under laboratory conditions. The survival and failure time analysis showed that the survival of the pathogen differs significantly after mild frost (all the isolates tested survived temperatures between –0.1 and –5.0 °C during the entire testing period) and heavy frost (the pathogen died after 21 days of incubation at –7.5 °C and after 2 days at –10.0 °C). Moreover, the viability of the pathogen decreased significantly if the temperature of –5.0 °C was maintained for at least 1 week and the temperature of –7.5 °C persisted in laboratory conditions for at least 4 days. The results of the study proved the pathogen to be very sensitive to heavy frost. The low-temperature limits for PAA occur regularly in Central Europe in January. It is probable that these temperatures can reduce PAA populations in diseased black alder stems. The climate change characterised by increases in the lowest minimum winter temperatures in Central Europe (as hypothesised by IPCC) may pose a significant risk for affected alder population in the area.

Highlights

The alder pathogen Phytophthora alni subsp. alni Brasier et S.A
The successful survival of the black alder pathogen can be affected by the winter temperature for several reasons: (1) the absence of chlamydospores as potential resting structures (Brasier et al 2004); (2) the failure of oospore germination connected with meiotic irregularities in this hybrid (Brasier et al, 2004; Delcán and Brasier, 2001); (3) the reported poor survival ability of the pathogen in the soil and the rhizosphere (Delcán and Brasier, 2001; Jung and Blaschke, 2004)
The temperatures –0.1 and –2.5 °C did not have a significant effect on the viability the incubation lasted for 4 weeks

Summary

Introduction

Alni Brasier et S.A. Kirk (PAA) causes devastating epidemics in black and grey alder in many European countries (Gibbs et al, 1999; Jung and Blaschke, 2004, 2006; Schumacher, 2006; Streito et al, 2002), including the Czech Republic (Černý and Strnadová, 2010). The successful survival of the black alder pathogen can be affected by the winter temperature for several reasons: (1) the absence of chlamydospores as potential resting structures (Brasier et al 2004); (2) the failure of oospore germination connected with meiotic irregularities in this hybrid (Brasier et al, 2004; Delcán and Brasier, 2001); (3) the reported poor survival ability of the pathogen in the soil and the rhizosphere (Delcán and Brasier, 2001; Jung and Blaschke, 2004)

Objectives

Methods

Results

Discussion

Conclusion