Fusarium head blight of barley

The disease is caused by various fungal species: Fusarium graminearum, F. culmorum, F. avenaceum, F. poae, and F. sporotrichioides. The infection manifests between flowering and grain filling as premature bleaching of individual spikelets or parts of the spike. Mycelium develops at the junctions of the glumes, changing in color from white to orange-red over time, which corresponds to the formation of sporodochia.

Infected grain loses its luster, becomes wrinkled and shriveled, and acquires a whitish or pinkish-brown hue. A spiderweb-like coating is often found in the grain crease. With mild development, symptoms may be latent, while the grain remains contaminated with mycotoxins such as deoxynivalenol, zearalenone, and T-2 toxin.

Barley resistance is quantitative and controlled by QTLs located, in particular, on chromosomes 2HL and 4HL. Breeding programs utilize the Schroeder and Christensen classification of resistance, which includes protection against primary infection, spread of the infection within the spike, mycotoxin accumulation, and tolerance.