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Phytotoxicity of T-2 Toxin Produced by Fusarium tricinctum. W. F. O. Marasas, Former Research Assistant, Department of Plant Pathology and Biochemistry, University of Wisconsin, Madison 53706, Present address of senior author: Plant Protection Research Institute, Private Bag 134, Pretoria, Republic of South Africa; E. B. Smalley(2), J. R. Bamburg(3), and F. M. Strong(4). (2)(3)(4)Professor, former Research Assistant, and Professor, respectively, Departments of Plant Pathology and Biochemistry, University of Wisconsin, Madison 53706. Phytopathology 61:1488-1491. Accepted for publication 19 July 1971. DOI: 10.1094/Phyto-61-1488.

Fusarium tricinctum isolates which produced T-2 toxin [4, 15-diacetoxy-8-(3-methylbutyryloxy)-12, 13-epoxy-^Δ9-trichothecen-3-ol] caused severe wilt of Early Perfection pea seedlings within 30 hr, and complete necrosis with 72 hr after root immersion in aqueous suspensions prepared from agar cultures. Isolates of F. tricinctum and F. roseum which did not produce T-2 toxin had no observable effect on pea seedlings. Crystalline T-2 toxin produced exactly the same symptoms in pea seedlings as T-2 toxin-producing Fusarium tricinctum cultures. Root immersion time had a slight effect on subsequent symptom expression. With an immersion time of 20 min, concentrations of T-2 toxin as low as 2.5 ppm could be detected by means of symptom expression alone. Aqueous solutions containing 5.0 ppm of T-2 toxin caused a 40% reduction in average fresh weight and length of pea seedlings 7 days after root immersion for 20 min. T-2 toxin concentrations as low as 0.625 ppm, or 0.0625 mg T-2 toxin in the test solution, caused statistically significant reductions in average fresh weight and length of pea seedlings.