Trichoderma ear rot is one of the less common ear rots of corn in Kentucky. However, occasionally we do see severe outbreaks of this disease in sporadic fields.
This ear rot produces abundant growth of dark green to bluish-green fungal material between kernels, often involving much of the ear (Figure 1).
Figure 1. Trichoderma ear rot of corn. (Photo: Paul Vincelli,UK)
Sometimes, in severely affected ears, kernels germinate within the husk (Figure 2).
Figure 2. Corn ear with Trichoderma ear rot, with some kernels germinating in the husk. (Photo: Bill Meacham, Pioneer Hi-Bred)
Occasionally, Trichoderma ear rot is confused with other greenish ear rots, such those caused by Penicillium spp., Aspergillus spp., and Cladosporium spp.
Here are a few things we have observed in outbreaks of Trichoderma ear rot:
- Diseased ears are commonly associated with injury to the developing ear, such as that caused by feeding by flocks of birds (Figures 3 & 4). Injury to the developing ear or husk may be a factor that encourages severe Trichoderma ear rot to develop. Such injuries would provide avenues for windblown spores and rainfall to enter the ear, setting the stage for later ear rot development.
- Certain species of Trichoderma may produce mycotoxins, including T-2 toxin. This mycotoxin is generally uncommon in foods in the USA but can be more common elsewhere. In two cases where we tested badly diseased grain for possible toxins, including T-2 toxin, no mycotoxin was detected.
Figure 3. Corn ear showing bird damage. (Photo: Paul Vincelli, UK)
Figure 4. Same ear as in figure 3, with husk leaves partially removed. (Photo: Paul Vincelli, UK)
Where Trichoderma ear rot is severe, farmers are recommended to harvest and dry the grain as soon as is feasible. Moldy grain should be stored separately from good grain, and it should be utilized as quickly as possible.
By Paul Vincelli, Extension Plant Pathologist
Kentucky Pest News 