Fusarium Pseudograminearum - Hosts and Symptoms

Hosts and Symptoms

F. pseudograminearum has a limited host range, only infecting species of wheat and barley. F. pseudograminearum can infect seedlings, but can also infect the crowns of mature wheat hosts. Crown Rot of Wheat produces asexual structures called conidiospores, which are produced in sporodochium structures inside the stem of the infected host. As the conidiospores germinate and invade the xylem and pith of the stem, both the stem and crown develop a red-brown or white discoloration. The primary infection of the host’s xylem is thought to occur at the crown or lower sheath of the stem from stubble containing a spore and mycelial inoculum. The infection of the xylem leaves the tissue water-soaked and with a pink or salmon color. As the infection proliferates the crown then becomes punky and is ultimately dysfunctional.

Due to the vast infection throughout the host, the plants growth is stunted and will show incomplete grain fill. As well as infecting the xylem and pith of the host, F. pseudograminearum produces mycotoxins once it has fully been established. Mycotoxins are toxins produced by fungi that are harmful to animals and human if consumed. F. pseudograminearum produces the trichothecene mycotoxin DON, which spreads throughout the plant stem and builds up in the tissue. The production of DON can produce the formation of whiteheads, which are heads of grain that died prematurely. It is known that F. pseudograminearum doesn’t infect the heads of the wheat, but the formation of the “whiteheads” is a secondary symptom of the buildup of the mycotoxin DON. The transport dysfunction occurring in the xylem and the buildup of mycotoxin DON will ultimately lead to death of the infected wheat plants.