Real-time PCR to study the effect of timing and persistence of fungicide application and wheat varietal resistance on Mycosphaerella graminicola and its sterol 14α-demethylation-inhibitor-resistant genotypes.
BACKGROUND
Sterol 14α-demethylase inhibitors (DMIs) have been widely used for more than 20 years against wheat Septoria leaf blotch. However, resistance towards DMIs has increased in recent years. The objective of this study was to evaluate the effect of fungicide timing and persistence and wheat resistance varietal on Mycosphaerella graminicola and its DMI-resistant genotypes.


RESULTS
Using qPCR, M. graminicola was detected 2 weeks later in the resistant cultivar than in the susceptible cultivar. A high proportion of DMI-moderate resistant genotypes (≥94%) was found in all samples, with an average of 74.2, 0.1 and 19.7% for R6, R7- and R7+ genotypes, respectively. Distribution of DMI-resistant genotypes was neither affected by different wheat cultivars nor by analysis dates. Electron microscopy coupled with qPCR analysis showed that the DMI fungicide prothioconazole had a significant inhibitive effect against spore germination and post-germination. However, the preventive treatment was the most effective, but it was affected strongly by fungicide persistence.


CONCLUSION
Preventive fungicide applications are more effective against Septoria leaf blotch than the curative treatments, so persistence and wheat varietal resistance should be taken into account in the management of this disease. It would seem that none of the studied factors affect the frequency of DMI-resistant genotypes.
['Selim|Sameh|S|', 'Roisin-Fichter|Céline|C|', 'Andry|Jean-Baptiste|JB|', 'Bogdanow|Boris|B|', 'Sambou|Renée|R|']
D058888:14-alpha Demethylase Inhibitors D001203:Ascomycota D025141:Drug Resistance, Fungal D005656:Fungal Proteins D005659:Fungicides, Industrial D005838:Genotype D010935:Plant Diseases D060888:Real-Time Polymerase Chain Reaction D058886:Sterol 14-Demethylase D014908:Triticum
real-time PCR wheat varietal resistance Mycosphaerella graminicola DMI-resistant genotypes epidemiology fungicide efficiency