Disease Note

First Report of a Rot of Lithops spp. Caused by Fusarium oxysporum.. D. M. Gerten, Department of Plant, Soil, and Entomological Sciences, University of Idaho, Moscow 83843. R. L. Bowden, Department of Plant, Soil, and Entomological Sciences, University of Idaho, Moscow 83843. Plant Dis. 69:811. Accepted for publication 14 May 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-811b.

Fusarium oxysporum Schlecht, emend. Snyd. & Hans. was isolated from rotted leaves of two Lithops plants (stone plants) of undetermined species obtained from two commercial sources and also from apparently healthy roots of a symptomless plant. Leaves of healthy plants were punctured and inoculated with mycelial plugs or macroconidial and microconidial suspensions (10⁴ spores / ml) of single-spore F. oxysporum isolates from each of the three sources. All three isolates caused extensive yellowish brown dry rot of leaves of L. karasmontana (Dint. & Schw.) N. E. Br. and L. olivacea L. Bol. within 1–2 wk at about 24 C, and most plants were killed within 4–6 wk. L. localis var. terricolor (N. E. Br.) deBoer & Boom and L. deboeri Schw. rarely developed rot and were never killed. F. oxysporum was consistently reisolated from rotted plants. No attempt has been made to determine a formae speciales designation.