Synergism in fungicide mixtures againstPseudoperonospora Cubensis
- 24 Downloads
- 4 Citations
Abstract
Mixtures of cymoxanil with mancozeb (Mancur) or with mancozeb plus oxadixyl (Pulsan, Sandocur-M) were effective in controlling either metalaxyl-sensitive (MS) or -resistant (MR) isolates ofPseudoperonospora cubensis on cucumbers (cv. ‘Elem’) in growth chambers. Metalaxyl+mancozeb (Ridomil-MZ) and oxadixyl+mancozeb (SAN-518) mixtures were effective against the metalaxyl-sensitive but less so against the metalaxyl-resistant isolate. Fungicide mixtures were far more effective in controlling either the sensitive or the resistant isolates than were the individual components applied alone, thereby representing significant levels of synergistic interactions. Increased efficacy of mixtures relative to their combined components (synergy factor) was calculated by the Wadley method. Mixtures containing cymoxanil showed high synergy factors against the resistant isolate, whereas Ridomil-MZ and SAN-518 did not evince this phenomenon. We concluded that cymoxanil mixtures might be suitable for the control of downy mildew incited by a metalaxyl-resistant isolate ofP. cubensis.
Key Words
Chemical control fungicide interaction oomycetes phenylamides Curzate fungicidal mixturesReferences
- 1.Cohen, Y. and Coffey, M.D. (1986) Systemic fungicides and the control of oomcytes.A. Rev. Phytopath. 24:311–338.CrossRefGoogle Scholar
- 2.Cohen, Y., Reuveni, M. and Samoucha, Y. (1983) Competition between metalaxyl-resistant and sensitive strains ofPseudoperonospora cubensis on cucumber plants.Phytopathology 73:1516–1520.CrossRefGoogle Scholar
- 3.Gisi, U., Binder, H. and Rimbach, E. (1985) Synergistic interactions of fungicides with different modes of action.Trans. Br. mycol. Soc. 85:299–306.CrossRefGoogle Scholar
- 4.Grabski, C. and Gisi, U. (1987) Quantification of syngergistic interactions of fungicides againstPlasmopara andPhylophthora.Crop Prot. 6:64–71.CrossRefGoogle Scholar
- 5.Levy, Y., Benderly, M., Cohen, Y., Gisi, U. and Bassand, D. (1986) The joint action of fungicides in mixtures: comparison of two methods of synergy calculation.OEPP/EPPO Bull. 16:651–657.Google Scholar
- 6.Moss, M.A. (1987) Resistance to metalaxyl inPseudoperonospora cubensis causing downy mildew of cucumber in South Florida.Pl. Dis. 71:1045.CrossRefGoogle Scholar
- 7.Ray, A.A. [Ed.] (1982) PROBIT. SAS User’s Guide: Statistics. SAS Institute, Inc., Cary, NC.Google Scholar
- 8.Reuveni, M., Eyal, H. and Cohen, Y. (1980) Development of resistance to metalaxyl inPseudoperonospora cubensis.Pl. Dis. 64:1108–1109.Google Scholar
- 9.Samoucha, Y. and Cohen, Y. (1984) Differential sensitivity to mancozeb of metalaxyl-sensitive and metalaxyl-resistant isolates ofPseudoperonospora cubensis.Phytopathology 74:1437–1439.CrossRefGoogle Scholar
- 10.Samoucha, Y. and Cohen, Y. (1985) Occurrence of metalaxyl-resistant isolates ofPseudoperonospora cubensis in Israel: a five-year survey.OEPP/EPPO Bull. 15:419–422.Google Scholar
- 11.Samoucha, Y. and Cohen, Y. (1989) Control of late blight in field-grown potatoes by synergistic fungicidal mixtures.Pl. Dis. 72 (in press).Google Scholar
- 12.Samoucha, Y. and Gisi, U. (1987) Effects of disease intensity and application type on efficacy and synergy of fungicide mixtures.Phytopathology 120:44–52.CrossRefGoogle Scholar
- 13.Wadley, F.M. (1945) The Evidence Required to Show Synergistic Action of Insecticides and a Short Cut in Analysis.Circ. US. Dep. Agric., ARA-Bur. Ent. PL Quar. ET-223. Google Scholar
- 14.Wadley, F.M. (1967) Experimental Statistics in Entomology. Graduate School Press, Washington, DC.Google Scholar