Effects of Disease Intensity and Application Type on Efficacy and Synergy of Fungicide Mixtures Against Phytophthora infestans

Abstract

Of eleven tomato cultivars ‘Baby’ was the most susceptible to Phytophthora infestans. The sporangium concentration of the fungus and the methods of fungicide application had a significant effect on the efficacy of oxadixyl, mancozeb and cymoxanil when tested singly or in mixture against sensitive and phenylamide resistant strains of P. infestans on tomato. Mancozeb was the least effective fungicide, its activity decreased significantly with increasing numbers of sporangia used for inoculation (increasing disease pressure) and its efficacy was dependent on the method of application. Oxadixyl and cymoxanil showed much stronger antifungal activities (except oxadixyl against resistant strains) which did not depend on the number of sporangia or method of fungicide application. The mixture of oxadixyl, mancozeb and cymoxanil was equally active and was independent of application type, sporangium concentration and level of sensitivity of the fungus. Mixtures of the single components showed synergistic interactions up to levels of 20, depending on the activity of the individual fungicide and the different disease intensities. Three‐way mixtures containing oxadixyl, mancozeb, and cymoxanil represent therefore promising possibilities in practice for strong disease pressure, even when resistance problems are expected.

Synergistic anti‐oomycete effect of melatonin with a biofungicide against oomycetic black shank disease

“…Synergistic therapeutics have been applied in clinical medicine, such as oxaliplatin and irinotecan on AZ‐521 stomach cell, or gefitinib and PD98059 on MDA‐361 breast cancer cell . Furthermore, synergistic methods were also widely used in plant pathogens control, for example, combination of cymoxanil and oxadixyl to prevent Phytophthora infestans . Our results imply that the combination could be applied widely with the potential for increasing efficiency of drug, decreasing dosage of drugs, and delaying drug resistance for controlling oomycetic diseases.…”