Sweet Corn Smut is a fungal disease that is more likely to occur in very warm summers. This disease is not transmitted within the plant and infected and healthy cobs may develop on the same plant.
The stems and occasionally the leaves can be malformed. Individual kernels on the cob swell and become pale grey in colour, rupturing to release large amounts of black spores. The spores can either germinate straightaway or remain in the soil and on plant debris. In wet weather the spores can run down the plant as a black liquid. This disease can spread through the crop in the air or by water splash.
There are no control measures available, infected plants and plant debris should burnt. Sweet Corn should not be grown on the same site for at least five years.