A dry early June delayed disease progression in corn, but we have received reports of gray leaf spot (GLS), tar spot, and to a lesser extent, northern corn leaf blight (NCLB) after recent wet, humid conditions. Corn growth and development is variable across Ohio, ranging from VT to R3 (“milk” stage). Continued scouting is needed, especially in fields with susceptible hybrids and a history of foliar diseases. Scouting efforts should also focus on continuous-corn, no-till fields, since fungal pathogens causing disease can overwinter on crop residue. When walking fields, keep an eye out for these foliar diseases:
Gray leaf spot: symptoms of GLS include tan, rectangular lesions (Figure 1) up to 2-4 inches long that first appear on lower leaves. Lesions are bordered by leaf veins and can turn gray later in season. Infection requires dew or foggy conditions and high relative humidity in the canopy.
Having trouble with early disease diagnosis? See the article in this issue by Paul and Rotondo for information on how to handle and send samples to the plant disease clinic for laboratory diagnosis, confirmation, and monitoring of disease spread, particularly tar spot.
Source: osu.edu
Photo Credit: gettyimages-nes
Categories: Ohio, Crops, Corn