Cross-resistance among flumorph, dimethomorph and iprovalicarb.

Abstract

<p>Log-transformed EC₅₀ values (the effective concentration for causing 50% inhibition of mycelial growth inhibition of <i>Phytophthora melonis</i>) for isolates of <i>P. melonis</i> were compared among the three carboxylic acid amide fungicides using Spearman’s rank correlation coefficients. (A), (B), and (C) indicate positive cross-resistance among flumorph, dimethomorph, and iprovalicarb; (D-F) include only the higher EC₅₀ values from (A-C), i.e., EC₅₀ values from CAA-resistant isolates. (D) reveals a positive correlation between the EC₅₀ values for dimethomorph and flumorph among CAA-resistant isolates, while (E) and (F) reveals a negative correlation between iprovalicarb and flumorph and between iprovalicarb and dimethomorph among CAA-resistant isolates.</p