First record of Dactylonectria macrodidyma causing black root rot on strawberry

Strawberry is a major fruit cultivated in Kerman greenhouses. During visiting strawberry cultivation greenhouses, black root rot symptoms were detected on strawberry plants. In order to identify the causal agents of the disease, symptomatic tissues were collected and transferred to the laboratory. Cylindrocarpon-like isolates were consistently recovered from infected tissues.  Based on morphological characteristics as well as sequence data, the causal agent was identified as Dactylonectriamacrodidyma. Colonies of D. macrodidyma on PDA were brown with yellow (honey) pigmentation at the margins. Macroconidia on SNA medium were 1–3 (–4) septate, straight, cylindrical (sometimes widening toward the tip), apical cell slightly bent to one side, 40 (±11) × 6.3 (±1.8) µm with free-standing, slender, unbranched conidiophores. Microconidia with 0–1 septum, ellipsoid and ovoid 10.5 (±3.2) × 4.1 (±1.6) µm. The results of pathogenicity tests showed that the tested isolates were pathogenic to strawberry. According to the knowledge, this is the first report of D. macrodidyma on strawberry.