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Poster: Biology & Disease Mgmt: Chemical Control


Effect of fungicide applications on Monilinia fructicola population diversity and transposon movement
M. DOWLING (1), H. Boatwright (1), G. Schnabel (1), P. Bryson (1), J. Wilson (1), Z. Fan (1), S. Everhart (3), P. Brannen (4) (1) Clemson University, U.S.A.; (2) Clemson University, U.S.A.; (3) University of Nebraska, Lincoln, U.S.A.; (4) University of Ge

In this study we investigated whether previously reported, fungicide-induced mutagenesis observed in vitro in M. fructicola can also accelerate genetic changes in field populations. Azoxystrobin and propiconazole were applied at half label rate to nectarine trees for two consecutive years in weekly intervals for three months between bloom and harvest. Single spore isolates were obtained from blighted blossoms, corresponding cankers, and from fruit to investigate phenotypic and genotypic changes. In both years, isolate populations collected from fungicide-treated fruit and from untreated control fruit were not statistically different in haploid gene diversity (p > 0.45 for 2013), (p > 0.46 for 2014), allele number (p = 0.88 for 2013), (p = 0.41 for 2014), and effective allele number (p > 0.88 for 2013), (p > 0.81 for 2014). Isolates from blossoms and corresponding cankers of fungicide treatments had no changes in simple sequence repeat size or evidence for induced transposon translocation. No emergence of reduced sensitivity to azoxystrobin, propiconazole, iprodione, and cyprodinil that would indirectly indicate increased genetic diversity was detected. Our results indicate that fungicide-induced, genetic changes may not occur as readily in field populations as they do in populations exposed continuously to sublethal doses in vitro.