On Thursday, 14 August, Curvularia leaf spot was observed in a field trial (Fig. 1A) and at a demonstration site in Central Iowa. Small circular-to-oval-shaped (up to 1/8” diameter and ¼” long) lesions were observed in the mid- and upper canopy. The spots have a whitish center and are surrounded by a dark-green water-soaked margin that eventually becomes orange-brown with a yellow halo (Fig. 1B).
Fig. 1. Curvularia leaf spot of corn observed in a field trial on 14 August in central Iowa (A); close-up of Curvularia leaf spot showing early lesions with a white center and water-soaked margin, and mature lesions with a white center, orange-brown margin, and yellow halo (B).
Symptoms of Curvularia leaf spot resemble those of eye spot. Eye spot, however, is favored by cool (60s to low 70s °F), wet weather. Consequently, eye spot is usually observed early on in the growing season, prior to pollination.
Curvularia leaf spot has been reported in MS, LA and KY. The effect of Curvularia leaf spot on yield in the U.S. is unknown and is currently being investigated; it is one of the most important diseases affecting corn in China.
Curvularia leaf spot is one of the diseases the National Predictive Modeling Tool Initiative is developing models for, and consequently it will be part of the suite of Crop Disease Forecasting Tools available on the Crop Protection Network website
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- Professor of Plant Pathology and Microbiology
- Extension Field Crops Pathologist
- Plant Disease Diagnostician