Fusarium Pseudograminearum - Disease Cycle

Disease Cycle

The disease cycle of F. pseudograminearum includes both sexual and asexual stages, however the sexual stage has been observed to not play an important role in the establishment of the disease. Overwintering on crop residue, seeds, or in the soil is easily accomplished for this Fusarium species due to the formation of survival structures called chlamydospores. As spring arrives the chlamydospores are signaled to germinate producing asexual structures called conidia. As mentioned previously, the formation of sexual structures are rare in the field, but the pathogen’s teleomorph would produce structures called perithecia. As the perithecia form they would produce asci that contain ascospores inside. The perithecia forcibly discharge the ascospores and then those airborne spores are disseminated either by wind, rain, or animal. These sexual spores then land on a mature wheat host and would start to colonize the stem and area around the crown as summer proliferates. However, the asexual stage of F. pseudograminearum is a much simpler cycle that produces the most damage to the wheat.

Conidia, produced from the chlamydospores in soil or spread by wind, can infect wheat through natural openings and colonize the xylem and pith of the host. Formation of asexual structures called sporodochium can produce even more conidia, which act as a repeating infection stage. Soon the wheat plant will have multiple infection sites, most of which are near the crown. As harvest season approaches at the end of the summer the dry warm environment has allowed F. pseudograminearum to colonize the plant and start producing harmful mycotoxins that produce secondary symptoms in the grains of the wheat. Mycotoxin DON is harmful to animal and humans that consume the wheat, which makes the crop inedible and thus a costly problem (Miedaner et al 2008).