Managing Molded and Damaged Grain

Challenging conditions can occur at harvest. The risk of lodging, stalk and ear diseases, or reduced grain quality increases the longer corn is in the field.

Delayed maturity of corn (late planting, cool growing season, or wet soil conditions) can translate into slow drydown of mature corn grain. Temperature and humidity influence the rate of drydown, which declines quickly in late September and October. Wetter grain at harvest increases the need for artificial drying of grain and increased production costs.

Higher grain moisture and ear rot damage can increase the amount of fine materials in the bin which can interfere with aeration or be a source of disease, mold, or toxins associated with ear rot. Checking grain moisture in each load and throughout the storage period can help prevent spoilage.

Adjust equipment to minimize the degradation of wet grain quality:

Combine settings. Balance the need for aggressive shelling to get small kernels off the cob against the extra kernel damage that is caused by aggressive shelling. Balance the need for aggressive cleaning to remove chaff and small particles against yield losses that occur when small, light kernels are blown out of the combine.

Manage fines and chaff. Fine particles and chaff affect airflow movement and increase mold problems in storage. Consider cleaning grain to remove fines and chaff, “core” bins to pull fines out of the center, or make sure that fines and chaff are uniformly distributed throughout the storage bin rather than being concentrated in certain areas.

Dry grain uniformly.Check grain moisture content of every load of corn and reset dryer controls based on changing moisture levels. Make sure that the moisture content of dried corn is low enough for safe storage (15% for winter storage, 14% for storage into spring and summer, 13% for a year or more storage time) and consider reducing these moisture levels by about a percentage point for corn that is immature, frost damaged, or low test weight.

Dry corn gently. High drying temperatures can result in lower test weight and in more cracked and broken kernels. Natural-air drying (no heat) gives better test weight and less kernel damage than gas-fired drying. Use slow cooling methods after gas-fired drying to minimize quality problems.

  • Aerate stored grain to 20-30°F for winter storage.
  • Check stored grain frequently so that you can quickly address minor spoilage problems before they become big, costly problems.
  • Moldy grain can have a shorter storage life than clean grain. Don’t mix new with old grain.
  • Temporary grain piles should be at commercial facilities not on farm sites. Small piles tend to spoil more rapidly than large piles and large piles are easier to aerate.

To keep wet grain going into storage from heating and losing quality, run the aeration fan continuously whenever grain exceeds 18% moisture and grain temperature is above 50°F. The length of time corn can be kept under constant temperature and moisture content before it losses 1/2% dry matter (the maximum loss to maintain current market grade) is shown in Table 1. General rules of thumb for corn above 16% moisture are storage life is half as long at given temperature for every 2 points of moisture greater than 16% and storage life is half as long for every 10°F increase in temperature. Soybeans in storage have a shelf life similar to corn that is 2% greater in moisture content (Table 1).


Damaged Corn