Northern corn leaf blight symptoms

By:  Stephanie Karhoff

Preventing significant yield losses from disease is likely on the forefront of growers’ minds following the 2021 growing season. A new product in our disease management toolbox is FMC’s fungicide Xyway™ LFR®. OSU Extension eFields program is partnering with growers to conduct on-farm trials evaluating the effect of an at-plant soil application of flutriafol (Xyway) on corn health and yield. Information from this trial will be used to improve corn disease management recommendations for growers throughout the state. Continue reading →

By:  Pierce Paul, Wanderson B. Moraes, Marian Luis

After walking more than 40 corn fields and sampling more than 3,500 ears, we believe that Gibberella ear rot (GER), and consequently, vomitoxin levels likely will be much lower this year than they were last fall. This is because conditions during the weeks after silking were considerably less favorable for the disease to develop and the toxin to contaminate grain this year than last year. However, as is often the case, there were a few exceptions. We found low levels of GER in (sentinel-type) plots and research fields deliberately planted with hybrids that are highly susceptible to the disease, and these plots/fields will likely yield grain with some level of vomitoxin contamination (we are still processing our samples). Averaged across 10 locations, the incidence of GER on a susceptible hybrid ranged from 10 to 20%, i.e., 1 to 2 out of every 10 ears had visual symptoms of GER, and on average, less than 5% of the surface area of affected ears showed symptoms of the disease. Continue reading →

By:  Stephanie Karhoff

To growers’ dismay, 2021 is shaping up to be a “good” year for Tar Spot (“good” if you are a plant pathologist at least). Though the combine will have the last say on Tar Spot’s yield impact on corn fields across Williams County, it is already evident that Tar Spot has become more widespread across the county, state, and even the Corn Belt. Continue reading →

By:  Pierce Paul and Felipe Dalla Lana da Silva

Ear rots differ from each other in terms of the damage they cause (their symptoms), the toxins they produce, and the specific conditions under which they develop. GER leads to grain contamination with mycotoxins, including deoxynivalenol (also known as vomitoxin), and is favored by warm, wet, or humid conditions between silk emergence (R1) and early grain development. However, it should be noted that even when conditions are not ideal for GER development, vomitoxin may still accumulate in infected ears.

A good first step for determining whether you have an ear rot problem is to walk fields between dough and black-layer, before plants start drying down, and observe the ears. The husks of affected ears usually appear partially or completely dead (dry and bleached), often with tinges of the color of the mycelium, spores, or spore-bearing structures of fungus causing the disease. Depending on the severity of the disease, the leaf attached to the base of the diseased ear (the ear leaf) may also die and droop, causing affected plants to stick out between healthy plants with normal, green ear leaves. Peel back the husk and examine suspect ears for typical ear rot symptoms. You can count the number of moldy ears out of ever 50 ears examined, at multiple locations across the field to determine the severity of the problem.

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Tar spot on corn. Photo: Martin Chilvers, MSU.

By:  Stephanie Karhoff

As the season progresses, keep an eye for tar spot, a new corn disease caused by the fungus Phyllachora maydis. The pathogen originates from Mexico and Central America, but has made its way to the Buckeye State.

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