Gibberella Ear Rot in Corn

Gibberella ear rot is a common corn ear mold found throughout the Midwest and the Northeast cropping regions of the United States. The fungi name is Gibberella zeae which is synonymous with the fungi Fusarium graminearum.¹ It is also the causal agent of Gibberella stalk rot on corn and Fusarium head blight on wheat and barley.

Gibberella ear rot is primarily a late season corn disease that has a negative impact on harvest logistics, grain quality, and yield potential. Gibberella infection reduces grain dry matter which is important for grain yield potential and kernel weight and can produce mycotoxins. These implications, depending on severity, can increase the likelihood that elevators may reject loads due to mycotoxin contamination.

Identification

The severity of infection dictates how easily visual symptoms can be observed. In many light cases, there is minimal mold growth inside the husk; however, in severe cases the entire ear inside the husk can be moldy along with the exposed ear tip. The reddish/pink color helps distinguish Gibberella ear rot from most other ear molds (Figure 1).²

Toxicity

Gibberella ear rot is unique from other common ear rots as the fungus produces mycotoxins like deoxynivalenol and zearalenone. Deoxynivalenol (DON) is a vomitoxin that can be responsible for livestock refusing to eat which can lead to extreme weight loss or even death. Zearalenone consumption has been linked to breeding complications like infertility and fetus abortion.¹

Disease Cycle

Like many other corn pathogens, Gibberella zeae fungi overwinter on corn residue in the soil. Likewise, the infecting spores travel by insect, splashing rain, or wind to a susceptible host. Spores then germinate on injured/punctured (via insect, birds, or hail) kernels where entrance barriers like the ear husk have been compromised.³ Spores can also land on silks and travel down the silk into the husk where infection can begin. Infection generally occurs at the R1 reproductive growth stage (silking). The silks are the most susceptible in the first week of emergence from the ear shoot.¹

Favorable conditions of infection during silk emergence include cooler ambient temperatures and periods of higher moisture like heavy dews or light, persistent rains from mid-late summer thunderstorms.³ After infection has occurred, the fungus spreads up and down the infected ears until kernel moisture content dries below 18 percent. This means infected ears are under siege of the fungus for at least a couple of months. It is at this time that rapid kernel dry matter accumulation would generally be taking place.

Management

Unfortunately, there is no way to protect corn fields completely from Gibberella ear rot. However, there are different ways to manage and limit infection and growth of the fungus. Although there are no products on the market that offer 100% gene resistance, growers can select corn products with greater tolerance/defensive mechanisms that can slow or limit fungal growth. This can vary greatly among corn products. Products that exhibit physical characteristics like lose husks surrounding the ear are less likely to suffer from Gibberella ear rot as moisture is less likely to be trapped in the husk therefore limiting the number of conducive environments.¹ Your Channel^® brand agronomist can help determine adapted Channel^® brand corn products for your area.

If you have scouted and found Gibberella ear rot in your fields, there a few practices that can be implemented to help lessen the potential for damage:

• Plan to harvest infected fields first and dry to 15% kernel moisture content to help limit mold growth.⁴
• Isolate harvested infected grain from better quality grain to limit potential exposure and spread of mycotoxins.
• Check infected grain samples regularly if being stored for long periods of time.

Channel Agronomist
Luke Watson

Sources

¹Brown, S. and Kelly, H.M. Gibberella ear rot. The University of Tennessee Institute of Agriculture. https://guide.utcrops.com/corn/corn-ear-rots/gibberella-ear-rot/

²2019. Gibberella ear rot of corn. Crop Protection Network. A Product Of Land Grant Universities. https://cropprotectionnetwork.org/encyclopedia/gibberella-ear-rot-of-corn

³Pierce, P. 2020. Gibberella ear rots showing up in corn: How to tell it apart from other ear rots. C.O.R.N. Newsletter. Ohio State University Extension. https://agcrops.osu.edu/newsletter/corn-newsletter/2020-34/gibberella-ear-rots-showing-corn-how-tell-it-apart-other-ear-rots

⁴Tande, C. 2022. Gibberella and Fusarium ear rots developing in corn. South Dakota State University Extension. https://extension.sdstate.edu/gibberella-and-fusarium-ear-rots-developing-corn

Web sources verified 6/29/24. 1110_430837