Control of Silver Scurf on Potato by Dusting or Spraying Seed Tubers with Fungicides Before Planting

American Journal of Potato Research, Jul/Aug 2004 by (Lahkim), Leah Tsror, Peretz-Alon, Itzahk

In general, our findings are in agreement with previous reports regarding imazalil (Hide et al. 1988, 1994; Tsror (Lahkim) and Peretz-Alon 2002), prochloraz (Denner et al. 1997), and fludioxonil (Errampalli et al. 2001; Frazier et al. 1998). However, Hervieux et al. (2001) demonstrated that fludioxonil, mancozeb, iprodione, thiabendazole, imazalil, or azoxystrobin applied to seed tubers did not significantly reduce silver scurf severity on progeny tubers. These differences can be related to method of application (variations in sprayers, timing of treatment, etc.). Such differences may also occur between field experiments and the commercial use of fungicides (Hide 1986).

Fungicide combinations may be more effective than individual fungicide applications in controlling silver scurf (Frazier et al. 1998); however, it may be a dose effect rather than a synergistic effect between the fungicides. In our study, the concentration of mancozeb in the combined treatment was three times less than when applied alone, whereas the other fungicides in the combination were in similar concentrations as when applied alone. In Experiment III, the combined treatment of mancozeb with imazalil resulted in lower disease incidence and severity, in comparison with the application of each fungicide separately. In the other two experiments (I and II), disease incidence on daughter tubers with the combined treatments of mancozeb with fludioxonil or with prochloraz-Mn, was not significantly different than with the application of each fungicide separately, but the disease severity index was lower with the combined treatment of mancozeb and prochloraz-Mn, than with each of these treatments separately. Combined fungicide applications may be important as part of a fungicide resistance management strategy.

ACKNOWLEDGMENTS

We thank Janis Joseph for editing the manuscript. This publication is contribution from Agricultural Research Organization, Institute of Plant Protection, Bet Dagan, Israel, No. 520/03. The research was partially supported by The Vegetables Producing and Marketing Board, Israel.

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