شناسایی و بیماریزایی قارچ Dilophospora alopecuri عامل بیماری پیچاک یا خال سیاه گندم در استان ایلام

Dilophospora leaf spot or Twist disease of wheat has been observed in most wheat-growing regions around the world. This disease is often accompanied by Seed-gall nematode and Gummy spike blight diseases. Symptoms of the disease are found in the leaf area as small, long, or yellowish blotches, which appear to grow in the form of brown spots. As these spots come together, black lines appear on the leaf and glume which in severe cases may be fatal. If the disease affects the seedling, it causes deforming and twisting of the leaves and their surface is filled with gray mycelia. the symptoms of the disease are very similar to the flag smut disease, so the identification of this disease is of great importance. During the growing season of 2017-2018, samples were taken from wheat fields of Ilam province, especially in the county of Chardavol. From different farms, 8-5 plants that had symptoms of the disease were randomly removed and transferred to the lab. In order to isolate the Dilophospora fungus, an acidic PDA medium was used. For purification of fungi, two methods were used including single spore and hyphal tip. The purified fungi were identified based on the characteristics of the fungus including the pycnidia and conidiums. After culturing and purifying the fungi from the samples, 66 isolates of Dilophospora alopecuri Fries, 1849 [Telomorph: Dilophia graminis (Fuckel) Saccardo, 1993] were isolated and identified based on morphological characteristics. In order to do pathogenicity test, a suspension of spores was prepared. The inoculation of fungi was performed by spraying the suspension on wheat plants previously grown in pots. The pots were covered with nylon bags to maintain moisture. Three pots were considered as controls, which were sprayed with sterile water. After 15 to 20 days, the symptoms of the disease were observed on the leaves and finally the disease was re-isolated and identified.