Penetrative behaviors of fungicides systemic azoxystrobin and non-systemic chlorothalonil into apples were assessed with impacts by cuticular waxes of apples and systemic properties of fungicides. Wax-intact and -removed apples were immersed in diluted solutions of the fungicides and divided into washed and unwashed groups with running tap water. Apple samples collected at 1, 24, and 48 h after incubation were separated into four parts before analysis of fungicides: peel, pulp-1, pulp-2, and pulp-3. Most azoxystrobin residues (70.7−86.4%) in wax-intact apples were present in peels and were higher in pulp parts closer to peels. After removal of cuticular waxes, azoxystrobin concentrations in pulps were 2 times greater than those for wax-intact apples. Although washing apples with running tap water reduced 52.3−69.2% of azoxystrobin residues, the residues in pulps were still determined at similar concentrations before and after washing. On the other hand, chlorothalonil residues for all apple samples were determined in peels only regardless of wax removal and/or washing treatment, and 84.5−91.1% of the residues were removed from peels by washing. These results indicate how physicochemical properties of both fungicides could be influence their penetration behaviors through cuticular waxes of apples.

Penetrative behaviors of azoxystrobin and chlorothalonil into apples cuticular waxes and fungicide systemicity

254th National Meeting (2017)

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