گزارش وقوع سیاهک پنهان پاکوتاه گندم در استان لرستان

Stinking (dwarf) bunt is caused by Tilletia controversa K., is a disease which is observed in cool regions, and if infection percentage are very much, the 70-80% losses will be possible. Teliospores of this fungal pathogen only germinate when the soil temperature hovers around freezing for long periods of time. This condition is usually found under snow cover so dwarf bunt is restricted to areas where have long periods of snow, and is problematic in fields where untreated seed is planted or they were treated by fungicides which are registered only for loose smut and common bunt. Due to importance and nutritional value of wheat in Iran, some of wheat fields in Lorestan were visited in spring 2023. In Some fields with Azar2 and Varan cultivars, which were located in eastern regions of Lorestan, including Jahankhosh, Shapourabad and Chamansoltan, symptoms of stinky bunt were observed, incidence percentage in these regions were evaluated 0.5-0.6%. These fields were in snowy and cool heights of Aligudarz city. Infected plants had more and smaller tillers. Because infected seeds became filled with teliospores of pathogen, the size of mass were expanded and spikelets were flaring out. Also, dominance of dwarf plants in a field was another symptom of this disease. Black to brown teliospores inside of seeds had a typical smell like rotting fish. Microscopic observation of teliospores revealed typical spores of Tilletia controversa with reticulate membrane and gelatinous layer around spores. During harvest, the smut spores are released from infected heads as the heads pass through the combine, and they contaminate other seeds being harvested or are spread by the wind to the soil surface, later to be incorporated into the soil mass during cultivation. This disease is an important threat for standard seed production procedure. So, in cool and temperate and especially snowy regions, in which disease is probable, treatment of seeds by three purpose fungicides against loose, common, and stinking smut such as Difenoconazole must be necessary.