Fusarium species causing FEB can produce several types of spores. The asexual stage of the fungus produces spores called macroconidia. Some Fusarium fungi have a more complex life cycle including a sexual stage, for example F. graminearum. In the sexual stage the fungus produces spores called ascospores. The sexual stage form fruiting bodies called perithecia, in which ascospores are formed in a sac known as an ascus (plural asci). Some species including F. culmorum produes resistant chlamydospores which can survive for a long time in the soil.
Fusarium fungi can overwinter as saprotrophs in the soil or on crop debris that can serve as inoculum for the following crop. The fungus can also spread via infected seed. The presence of Fusarium fungi on crop debris or seed can cause Fusarium seedling blight and foot and root rot. Later, infection of the heads can occur with spores spreading by rain splash from infected crop residues. Another major infection route is airborne inoculum as spores can travel long distances with the wind. The cereal crop is most susceptible at flowering and the probability of infection rises with high moisture and humidity at flowering.
In wheat, Fusarium infects the head (hence the name “Fusarium head blight”) and causes the kernels to shrivel up and become chalky white. Additionally, the fungus can produce mycotoxins that further reduce the quality of the kernel.