Yellow spot flag leaf damage

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Yellow spot flag leaf damage

Photograph of wheat leaves flagging under the effect of infestation by the disease Yellow spot
Wheat leaves flagging under the effect of infestation by the disease yellow spot
© DPI&F
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Yellow spot is caused by the fungus Pyrenophora tritici-repentis. It survives in wheat and occasionally triticale stubble. In very rare cases the fungus may survive in barley stubble. Wet spores (ascospores) develop in fungal fruiting bodies on wheat stubble, spread during wet conditions and can infect growing wheat plants.

As the crop develops, masses of a second type of spore (conidia) are produced on old lesions and dead tissues. Conidia result in rapid development of the epidemic within a crop and spread of the disease to other crops and areas. Again, wet conditions are necessary for spore production and infection and strong winds are needed to spread the disease any great distance.

Severe yellow spot may result in short, spindly plants with reduced tillering and root development. Where conditions are favourable, plants may be fully defoliated soon after flowering.

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