Fungicide control of head smut (Sporisorium reilianum) of sweetcorn (Zea mays)

Abstract

A field trial was carried out to compare the efficacy of the fungicides carboxin + thiram (Vitafio®), carbendazim (Prolific®), tebuconazole (Raxil®), propiconazole (Tilt®), fiutriafol + imazalil sulphate (Vincit™), and azoxystrobin (Amistar®) as seed applications for the control of head smut of sweetcorn (Zea mays), caused by the fungus Sporisporium reilianum (Sphacelotheca reiliana). The trial was carried out in the Poverty Bay region of New Zealand in a field that had a previous history of head smut. Carbendazim, fiutriafol + imazalil sulphate, propiconazole, and azoxystrobin seed treatments resulted in significantly greater plant numbers and increased early plant growth compared with the untreated experimental control, carboxin + thiram, and tebuconazole treatments. Plots in the control and carboxin + thiram treatments had a relatively high number of stunted plants (<10 cm) 1 month after sowing (7.6% and 14.9% respectively). Carbendazim, tebuconazole, propiconazole, fiutriafol + imazalil sulphate, and azoxystrobin seed treatments all produced low numbers of stunted plants (0.4–3.1%). Of the plants in the untreated control plots, an average of 8.7% were infected with head smut at harvest maturity. Seed treatment with carboxin + thiram didnotreduce numbers of smutted plants compared with the untreated control. All other fungicides reduced the proportion of diseased plants. The most effective were propiconazole and fiutriafol + imazalil sulphate, which respectively gave 2.3% and 2.4% plants infected with head smut. Carbendazim, tebuconazole, and azoxystrobin were slightly less effective reducing infection to 5–6%. Fiutriafol + imazalil sulphate and propiconazole both offer alternatives to carboxin + thiram for control of head smut of sweetcorn. © 2006 Taylor & Francis Group, LLC.