Crown rot is a wide-spread fungus which causes considerable yield losses, with losses exceeding 80% in individual crops, especially in systems where tillage has been reduced and cereals are grown in close rotation. This subset contain wheat materials that are tolerant to crown rot.

Fusarium can occur in all winter cereals, and a wide range of pasture grasses and grass weeds. Crown rot has been reported in Australia, USA, South Africa, New Zealand, Italy, Morocco, Syria and Turkey. F. pseudograminarium is most prevalent in areas where spring wheat is grown in winter under mild temperatures, and then ripens under hot, dry conditions. F. culmorum is favored under similar conditions, but appears more common in cooler conditions. Most current varieties of wheat are susceptible to the fungi, though partial resistance will occur.

The crown rot fungus will cause whiteheads through necrosis of the crown and lower stem, causing premature senescence. These whiteheads can have no grain, pinched grain, or normal grain, depending upon the development of crown rot in relation to crop maturity. Under humid conditions, the fungus can cause pink pigmentation in the crown and lower leaf sheath. Browning of the lower stem is another fairly common symptom, but becomes less obvious in wet seasons.

Source: CIMMYT Wheat Germplasm Bank