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Poster: Biology & Disease Mgmt: Mycology


Fitness ability and fungicide sensitivity of Lambertella corni-maris isolates from apple
A. AMIRI (1), A. Hawkins (2), K. Mulvaney (2) (1) Washinton State University, U.S.A.; (2) Washington State University, U.S.A.

Lambertella corni-maris is a newly reported postharvest decay of apple. Additional knowledge is needed to understand disease ecophysiology and develop adequate control strategies. In this study, we investigated fitness ability of three isolates in vitro i.e. growth on different media, sensitivity to pH and osmotic stress and in vivo pathogenicity on nine apple cultivars. All three isolates grow significantly faster on apple juice agar compared to potato dextrose agar whereas growth on V8 agar and malt extract agar was intermediate. Isolates grew equally at pH ranging from 3 to 7 and growth was inhibited at pH ≥8. Significant sensitivity to osmotic stress was only observed at higher KCl concentrations (1M). L. corni-maris was pathogenic to all nine test apple cultivars, however, Honey Crisp, Fuji, Pixata, and Gala were significantly more susceptible compared to Cameo, Braeburn and Red Delicious. Furthermore, the sensitivity of 100 L. corni-maris isolates to fludioxonil, boscalid, pyraclostrobin, pyrimethanil and thiabendazole was evaluated using a mycelial growth inhibition assay. Mean EC50 values were 0.07, 0.84, 1.32, 2.45 and 3.68 µg/ml, respectively. Fludioxonil and pyrimethanil were highly effective in controlling the disease on detached fruit whereas thiabendazole was the least effective. Our results indicate that L. corni-maris may be able to survive extreme conditions and is better controlled by postharvest rather than preharvest fungicides.