Evaluation of temporal distribution of airborne inoculum of Zymoseptoria tritici and Puccinia triticina in Tunisia
Hassine M, Baraket M, Guesmi M, Ellouze W (2021) Evaluation of temporal distribution of airborne inoculum of Zymoseptoria tritici and Puccinia triticina in Tunisia. The Joint Canadian Fungal Research Network (CanFunNet) and Great Lakes Mycology Conference 2021/05/26 - 2021/05/28, Western University London, Ontario, Canada, p 66
Septoria tritici blotch (STB) (Zymoseptoria tritici) and stripe rust (Puccinia striiformis) are devastating foliar diseases affecting durum wheat in regions of Tunisia. The development of severe epidemics caused by these pathogens has been reported in many wheat-growing regions worldwide including Europe, Australia, Middle East, and North America. The quantification of airborne inoculum is a good technique to predict and understand the epidemiology of Z. tritici and P. striiformi. During the 2016-2017 growing season, volumetric Burkard 7-day spore traps and quantitative PCR (qPCR) were used to continuously quantify the airborne inoculum temporal distribution at one of the disease emerging hotspot areas of northwestern Tunisia. The qPCR monitoring of Z. tritici revealed a number of significant peaks during different periods of the growing season, such as mid-November (384.3 spores), March (264.7 spores), mid-April until the first week of May (a daily detection mean of 75.3 spores), and a higher intensity at the end of the season on June after exceptional precipitations (600 spores). However, P. striiformis was detected from the start of the survey during the sowing period in November to May with peaks during March and once again in April and May. Significant quantities (527.2 spores) and detection frequencies (± 10 % of days) of P. striiformis were observed mainly in March and once again in April and May with 553.4 and 397.32 spores respectively. The trapped inoculum of airborne Z. tritici and P. striiformis were positively and significantly correlated with STB and stripe rust disease severity in the field. Moreover, weather conditions such as temperature, humidity and precipitation are main contributors to the production and the quantity of airborne inoculum. Our results showed that the quantification of airborne inoculum could be an indicator for early detection of Z. tritici and P. striiformis incursion and spread before symptoms become evident and thereby become a useful tool to anticipate needs for management and optimization for timing of disease control products.