First Report of Fusarium equiseti Causing Leaf Yellowing and Stunting on Sugar Beet (Beta vulgaris L.) in Montana, USA

In May 2019, sugar beet (Beta vulgaris L.) seedlings were observed with stunted growth, yellowing of leaves, and dying seedling root tip tissue discoloration in Sidney (47.7167° N, 104.1563° W), Montana. The disease affected about 40% of the 10 ha commercial field. Roots of infected seedlings were surface sterilized with 70% ethanol for 30 seconds, rinsed with sterile distilled water and cultured on amended 50% potato dextrose agar (PDA) for 7 days at 25°C. The isolated fungus produced white to yellow aerial mycelium. Macroconidia (18.9 to 30.3×2.5 to 3.6 µm, 5-7 septate) exhibited dorsoventrally curvature. No microconidia were found. Chains of chlamydospores were observed in three weeks old culture. The morphological features of the isolates were consistent with Fusarium equiseti