Stored Grain Fungi

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Laura Sweets
Extension Assistant Professor
Commercial Agriculture Program
Department of Plant Pathology

There are a number of fungi which can invade and cause damage to grains and seeds. In general terms we can divide these fungi into two groups- field fungi and storage fungi.

Field fungi invade the seeds before harvest while the crop is still in the field. Field fungi may affect the appearance and quality of seed or grain. Usually damage caused by field fungi occurs before harvest, can be detected by routine inspection and does not continue to increase in storage if grain is stored at the proper moisture content and temperature. Most field fungi are more prevalent when rainfall is above normal during grain fill and harvest. Invasion by field fungi may be more severe is the crop has been damaged by insects, birds or hail. With corn, ears well covered by husks and maturing in a downwards position usually have less rot than ears with open husks or ears maturing in an upright position.

Field fungi common on corn in Missouri include species of Alternaria, Cladosporium, Aspergillus, Penicillium, Diplodia, Fusarium and Gibberella. Descriptions of the ear and kernel rots caused by these fungi on corn are given in Table 1 . Field fungi may also occur on soybean seed in the field with species of Phomopsis and Cercospora being the most common problems (Table 2).

Storage fungi (also called storage molds) are fungi which invade grains or seeds during storage. Storage fungi are usually not present to any serious extent before harvest. Small quantities of spores of storage fungi may be present on grain going into storage or may be present on spilled grain present in harvest, handling and storage equipment or structures. Under improper storage conditions this small amount of inoculum can increase rapidly leading to significant problems. The development of storage fungi in stored grain is influenced by the moisture content of the stored grain, the temperature of the stored grain, the condition of the grain going into storage, the length of time the is grain stored and the amount of insect and mite activity in the grain. The most common storage fungi are species of Aspergillus and Penicillium. These fungi are widely distributed and almost always present.

Conditions Under Which Storage Fungi are Likely to Damage Stored Grains

The major factors that determine when stored grains will be damaged by storage fungi are:

Management Practices to Minimize Damage from Stored Grain Fungi

Little can be done to prevent or reduce the invasion of crops in the field by field fungi. However, the following recommendations should help prevent storage fungi problems or minimize damage from storage fungi in stored grains.