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Table 1. Ear and Kernel Rots of Field Corn in Missouri

Disease: Black corn
Pathogen: Alternaria and Cladosporium species
Symptoms: Black, blue-black or olive green to olive brown mold growth develops on husks, kernels and cobs (Fig. 1). Individual kernels may have dark blotches or streaks. Pericarps may have split to reveal clumps or tufts of dark mold growth. Both fungi have common invaders of dead plant tissues so may be found on husks, leaves and stalks as well as on ears and kernels (Fig. 2).

Disease: Diplodia ear rot
Pathogen: Diplodia maydis and Diplodia macrospora
Symptoms: Dense white to grayish white mold growth matted between kernels and between the ear and the husks is common (Fig. 3). Small black fungal fruiting bodies may be scattered on husks, cob tissues and sides of kernels (Fig. 4). The husks of early infected ears appear bleached or straw colored. The entire ear may be grayish brown, shrunken, very lightweight and completely rotted.

Disease: Fusarium ear rot
Pathogen: Fusarium moniliforme
Symptoms: Damage tends to occur as a salmon-pink to reddish brown discoloration on caps of individual kernels scattered over the ear (Fig. 5). A powdery or cottony kernel or pink mold growth may develop on infected kernels. Frequently Fusarium kernel rot becomes established around tunnels made by corn earworms or cornborers.

Disease: Gibb ear rot
Pathogen: Gibberella zeae
Symptoms: Usually begins as a reddish mold at the tip of the ear (Fig. 6). Early infected ears may rot completely with husks adhering tightly to the ear and a pinkish to reddish mold growing between husks and ears. Although mold growth usually has pinkish to reddish color, it can appear yellow to yellow-orange or yellow-red. Gibb ear rot typically begins at the tip of the ear but under favorable conditions it can move down the ear causing extensive damage. It may also develop around injuries from hail, birds or insects (Fig. 7). Gibberella zeae is the perfect or sexual stage name for Fusarium roseum f. sp. cerealis.

Disease: Penicillium rot
Pathogen: Penicillium species
Symptoms: Evident as discrete tufts or clumps or a blue-green or gray-green mold erupting through the pericarp of individual kernels or on broken kernels (Fig. 8, Fig. 9). Colonies of Penicillium tend to be small, discrete colonies with a dusty or powdery appearance.

Disease: Aspergillus
Pathogen: Aspergillus flavus
Symptoms: Evident as a greenish-yellow to mustard yellow, felt-like mold growth on or between kernels, especially adjacent to or in insect damaged kernels (Fig. 10).

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