Fungicide baseline for mycelial sensitivity of Exserohilum turcicum, causal agent of northern corn leaf blight

Abstract

Northern corn leaf blight, caused by Exserohilum turcicum(Et), is one of the major corn diseases which can reduce grain yield and quality. The aim of this study was to determine the mycelial sensitivity of ten Etisolates, five from Argentina and five from Brazil, to six fungicides (carbendazim, captan, fludioxinil, metalaxyl, iprodione and thiram) used in seed treatment. The inhibitory concentration (IC50) was determined by using seven concentrations of the fungicides supplemented to the agar medium. The mycelial colony diameter was measured with a digital caliper. Experimental design was completely randomized with four replicates. Data on the percent mycelial growth inhibition were analyzed by logarithmic regression and the IC50 was calculated. The fungicide iprodione was the most potent, with IC50 < 0.01 mg/L, followed by fludioxonil, IC50 0.31 mg/L, and thiram, 1.37 mg/L. Carbendazim, metalaxyl and captan were classified as non-fungitoxic, showing IC50 > 50 mg/L for all isolates. Although iprodione is the most potent fungicide, it is not used for corn seed treatment. The IC50s obtained in this study can be used as baseline for future monitoring studies of Etsensitivity to fungicides.

Genetics of Resistance and Pathogenicity in the Maize/Setosphaeria turcica Pathosystem and Implications for Breeding

“…Some carboxamides (Iprodione), phenylpyrroles (Fludioxonil), and sulfur compounds (Thiram) are the most efficient fungicides against S. turcica mycelium growth, the latter two are used in maize seed treatment ( Rossi et al, 2015 ). Wathaneeyawech et al (2015a) found that spraying contact fungicides (Chlorothalonil, Mancozeb) or azoles (Difenoconazole) 7 days before inoculation was the best timing with Difenoconazole being the most effective fungicide.…”

Pathogenic variability in Exserohilum turcicum and identification of resistant sources to turcicum leaf blight of maize (Zea mays L.)

“…Most of the commercial cultivars of maize are more or less susceptible to Turcicum leaf blight. The reasons for lack of substantial durable resistance in the material may be attributed to the presence of variability in the population as the fungus E. turcicum is known to be highly variable in nature (Reddy et al 2013;De-Rossi et al, 2015). In order to develop the high yielding disease resistant cultivars, it is imperative to analyse and understand the variability in the pathogen.…”