Abstracts of Presentations at the 2024 APS Southern Division Meeting

Curvularia leaf spot of corn (Zea mays L.), caused by Curvularia lunata, is a relatively new disease for corn producers in the southern U.S. A limited amount of data exists on the potential yield losses associated with C. lunata as well as whether foliar fungicides can be used to manage the disease.Research trials conducted during 2023 used a Curvularia leaf spot-susceptible hybrid, Revere 1577VT2P.Trials were planted at four total locations in AR (n=2), LA (n=1), and MS (n=1) arranged as a two-factor factorial within a RCBD with four replications and a non-treated.Factor A (n=5) was fungicide consisting of four commercially available fungicides and a tank mix, and factor B was three application timings: Pre-tassel (V8), at tassel (VT/R1), and post-tassel (R2).The commercial fungicide products included representatives from the demethylation inhibitor (DMI), and quinone outside inhibitor (QoI) classes, a pre-mix combination consisting of a DMI + QoI, and a pre-mix consisting of a DMI + QoI + succinate dehydrogenase inhibitor (SDHI) class, and a DMI + QoI tank mix combination.Collectively based on application timing, and regardless of specific product, fungicide reduced observable disease by approximately 9.1 to 15.9% compared to the non-treated.The greatest reduction in Cuvularia leaf spot was observed following applications made at R2. Averaged across all locations, no yield benefit was captured regardless of application timing or fungicide product.