First report of leaf spot on sweet potato (Ipomoea batatas) caused by Alternaria alternata in Bulgaria

For the first time in Bulgaria, leaf spotting on sweet potatoes was investigated, and the causative agent, Alternaria alternata, was reported. The collected morphological data aimed to determine the identity of the fungus. According to Koch, the primary isolates from the damaged parts are identical to those produced from pathogenicity tests. In a laboratory we tested sixty-two leaves which had similar symptoms, with slight to medium-sized lesions with concentric circles and a yellowish halo. In general, the attack from Alt. alternate affected 7% of all plants and 32% of the examined leaves. The pathogen tests proved that the pathogen could also cause damage to tubers during storage. Knowing the etiology of diseases is essential for taking preventive measures and thus preserving the quality and quantity of agricultural production. Keywords: Alternaria alternata, sweet potato, leaf spots, pathogen, pathogenicity