Yellow rust [Puccinia striiformis]
Found primarily on wheat, but also on barley (specialized forms, so that the infection on wheat cannot transfer to barley).
Pattern of damage
In the early stages of epidemics, nest-wise occurrence spread over the entire field. Orange to lemon-yellow colored spore deposits break out of the leaves (Picture 1). 7-11 cm long lengthwise stripes from dense spore deposits and chlorotic discolorations arranged in parallel to the leaf nerves are typical (Picture 2). Later on, the entire leaf blade may be affected by the fungus. Finally, the leaves slit open and roll up.
Destroy volunteer grain prior to the emergence of fall seeding. Select a later seeding date in fall. Use varieties with a high degree of partial resistance
Detectable infection (attacks) from ES 31: immediate fungicide application.
Transmission: This disease can only survive on living plant tissue. The uredospores or the mycelium overwinter on volunteer or winter sown wheat, which provides the source of wind spread uredospores that can infect spring wheat in the spring. The germination occurs during darkness when moisture droplets are present, and from temperatures of 3 °C. An epidemic spread occurs mostly in May. Optimal development conditions are temperatures between 9 and 11 °C and high humidity. The pathogen penetrates the leaf via the stoma and forms hypnea. Just a few uredospores are sufficient to cause a severe infection since the fungus spreads half-systematically in the leaf tissue. Uredospore deposits are formed at the leaf veins, which break out of the epidermis as striated red blisters.