Leaf rust and occasionally some smut is present in corn plantings, but neither causes much economic damage. Bacterial wilt, transmitted by the corn flea beetle, can be a problem on early varieties. Maize dwarf mosaic virus, transmitted by aphids from johnsongrass, can severely stunt corn and cause economic loss. For specific disease control measures, see the latest edition of the Extension Agents Handbook. Irrigation Moisture is needed for effective herbicide activity and during the early stages of germination and plant emergence.
Soil moisture is also critical during silking and ear development.
Supplemental irrigation should be provided to meet the moisture requirement at least during these critical periods. Harvesting and Handling Sweet corn has a very short period of optimum harvest maturity, and quality changes rapidly prior to and following the peak. Unfortunately, appearance of unhusked ears provides little indication of optimum harvest maturity. Ears harvested immature will have small diameter, poor cob fill, and kernels that are watery and lack sweetness. At optimum harvest maturity the kernels are plump, sweet, milky, tender, and nearly maximum size.