Yellow rust

The fungus Puccinia striiformis f. sp. tritici is responsible for yellow wheat rust, named after its yellow color and the distribution of the fungus' uredia on the leaves, arranged in long linear striations parallel to the veins of the leaves. The symptoms of the disease can appear at any stage of crop development, but the yellowish color of the leaves is the most characteristic.

There are few studies on the occurrence, epidemiology, damage and control of yellow rust, but the little data that has been released shows that the disease causes losses in wheat crops that can vary between 5 and 50%.

With a simple ability to spread, the spores of wheat yellow rust are spread by the wind, easily crossing borders and reaching other countries. New aggressive strains of the fungus that causes yellow rust have emerged since the turn of the century and reached some countries, including Portugal in 2013 and 2014. According to data released by INIAV in 2015, the new strain of yellow rust (called Warrior) that affected wheat crops in Portugal in those years “combined a broad spectrum of virulence that allows it to attack both soft and durum wheat and triticale”, a hybrid cereal resulting from crossing wheat with rye.

Introducing resistant genes into plants, reducing the primary sources of spread and spraying with specific fungicides are the disease control measures currently available on the market, but they have proved to be ineffective.

It should be noted that wheat is the second largest cereal crop in the world (after corn) and a staple food, used to make flour and bread, in animal feed and as an ingredient in beer production.