Farmers can see a lot of different issues with their corn ears, which can tell them a lot about a corn plant’s development during the growing season. Ear size and kernels on the ear can indicate when the ear experienced stress and the severity of the stress. The following information is a guide to common corn ear issues as detailed by AgWeb.
Symptoms: Kernel row numbers may decrease by half from bottom to top of ear (for example, from 16 to eight kernel rows per ear). The ear length is usually about normal.
Causes: Severe stress during the seven- to 10-leaf collar stages and late application of sulfonylurea herbicide.
Blunt Ear Syndrome
Symptoms: Markedly reduced ear size and kernel numbers per row. Husk length and kernel row number may be normal.
Causes: Unknown but is most often associated with low temperature stress during early ear formation.
Multiple Ear Syndrome
Symptoms: Multiple ears on the same ear shank—sometimes five or six ears form a “bouquet.” Side ears may or may not be fully developed.
Causes: Unknown but similar to blunt ear syndrome.
Drought- Damaged Ears
Symptoms: Small, misshaped ears with poor kernel set at ear tip.
Causes: Severe drought and other stresses, such as nitrogen deficiency and high plant population.
Symptoms: Combination of tassel and ear in the same structure.
Causes: Injury to growing point, early-season compaction and saturated soil along field edges.
Diplodia Ear Rot
Symptoms: Partial or entire ear rotted by a white mold growing between the kernels; later the white mold changes to a grayish-brown growth over the husks and kernels. The entire ear may be shrunken.
Causes: Stenocarpella maydis fungus.
Poor, Incomplete Kernel Set
Symptoms: Poor reduced kernel set.
Causes: Similar to poor pollination at ear tip. (see next).
Symptoms: Poor tip fill or unfilled ear tips and kernel abortion at tip end of ear at blister and milk stages.
Causes: Stress during early kernel development, including severe drought, heat, nitrogen deficiency, foliar diseases and cloudy weather.
Symptoms: Missing kernel rows on outside or underside.
Causes: Unknown, but linked with stress after pollination.
Symptoms: Lightweight, poorly-filled ears with shrunken kernels and spaces between kernels.
Causes: Severe photosynthetic stress from the dough through
early dent stages.
Western Bean Cutworm Ear Injury
Symptoms: Scattered patches of partial or complete kernel destruction; often associated with mold growth on affected kernels.
Causes: Kernel feeding by Western bean cutworm.
Symptoms: Lightweight, weathered ears with damaged, discolored and moldy kernels; often associated with kernel sprouting.
Causes: Poor husk coverage at maturity, and upright ear orientation allows birds to feed on tip kernels.
Kernel Red Streak
Symptoms: Red streaks on sides of kernels, extending over the crown. Usually limited to kernels at tip of ear.
Causes: Toxin secreted during feeding by the wheat curl mite.