Figure 1. Stenocarpella (formerly known as Diplodia) ear rot typically begins at the base of the ear.	Figure 2. Fusarium spp. fungi can cause diseases of seedlings, stalks, and ears (pictured). These fungi are very common, opportunistic, and can infect anywhere on the ear. In this case, Fusarium infection was evident in ears wounded by hail. Under some conditions, Fusarium spp. may also produce mycotoxins.

September 7, 2007

Ear rotting fungi can continue to cause problems after harvest during storage if good storage conditions are not maintained. Remember that grain quality will NOT improve during storage. Under the best conditions, grain will maintain its quality, but is more likely to decline as fungi continue to grow in the bin.

Fungi that cause ear rot diseases, such as Stenocarpella (formerly known as Diplodia) or Fusarium (Figures 1 and 2, respectively), can survive a long time in the field and take advantage of wounds or favorable weather conditions to colonize ears. The same fungi that infect these ears can continue to grow very quickly in the humid conditions of a grain bin and substantially reduce grain quality and sometimes produce mycotoxins.

Managing Potential Grain Mold and Mycotoxin Contamination

First, dry grain to less than 15% moisture within 48 hours of harvest to slow the growth of grain molds. To further minimize mold and mycotoxin contamination, take the following steps with harvest and grain storage (Table III of Grain Molds and Mycotoxins in Corn).

1. Plant tolerant hybrids - some tolerant hybrids available
2. Ensure proper storage conditions - grain moisture, temperature, relative humidity
3. Minimize mechanical damage - harvest and postharvest shipping and handling
4. Minimize insect damage - pre-harvest and postharvest storage
5. Sanitation of storage facility - critical management practice
6. Chemical management - propionic acid, mineral oils
7. Assay moldy grain for mycotoxins - Toxicology Lab, Vet Diagnostic Center, UNL
8. Segregate, blend, or destroy contaminated grain - as per FDA regulations

Tamra A. Jackson
Extension Plant Pathologist, Lincoln