Sansevieria Thunberg, a member of the Agavaceae, contains around 60 species indigenous to Africa, Arabia, and India. Several species and their cultivars are commercially produced for use as interior and landscape foliage plants. During August 2010, several local nurseries submitted Sansevieria trifasciata samples to the Florida Extension Plant Diagnostic Clinic in Homestead. Leaves had round, water-soaked lesions and as the disease progressed, lesions rapidly enlarged and coalesced, resulting in severe leaf blight. Both young and mature leaves were affected. Closer examination of mature lesions revealed numerous brownish black acervuli that were produced in concentric rings, which is characteristic of anthracnose. The fungus was identified as Colletotrichum sansevieriae Nakamura based on typical cultural characteristics, conidial and appressoria morphology (1). Conidia were straight, cylindrical, obtuse at the apex, slightly acute at the base with a truncate attachment point, and 12.5 to 33 (18.4) × 4 to 8.9 (6.5) μm (n = 50). Hyphopodia were ovate, dark brown, single celled, and 6.2 to 8.7 (7.7) × 6.3 to 7.5 (7.3) μm (n = 25). Colonies on potato dextrose agar (PDA) were grayish white, felted with aerial mycelium, reverse gray to dark olivaceous gray, and partly cream in color. Sequences of the rDNA internal transcribed spacer (ITS) regions of two isolates (GenBank Accession Nos. JF911349 and JF911350) exhibited 99% nucleotide identity to an isolate of C. sansevieriae (GenBank Accession No. HQ433226) collected from diseased sansevieria in Australia. In addition, a maximum parsimony analysis (MEGA v.5.0) indicates that the two C. sansevieriae isolates from Florida are monophyletic (86% bootstrap support) with the type species from Japan (SA-1-2 AB212991; SA-1-1 AB212990) and the Australian isolate. Pathogenicity of our sequenced isolates was evaluated in greenhouse experiments. Twelve- to fourteen-week-old sansevieria plants were inoculated with conidial suspensions (1 × 106 conidia/ml) of C. sansevieriae. Inoculum or autoclaved water was sprayed over the foliage until runoff. Four plants of each of two economically important cultivars, Laurentii and Moonshine, were sprayed per treatment and the experiment was repeated twice. Inoculated plants were placed in a greenhouse at 29°C with 70 to 85% relative humidity. Plants were observed for disease development, which occurred within 10 days of inoculation for both cultivars. No symptoms developed on the control plants. Foliar lesions closely resembled those observed in the affected nurseries. C. sansevieriae was consistently reisolated from symptomatic tissue collected from greenhouse experiments. On the basis of molecular phylogenetics and distinguishing morphological characters, Nakamura et al. erected C. sansevieriae as a novel species that appears to be restricted to the host sansevieria (1). To our knowledge, this is the first report of C. sansevieriae causing anthracnose of sansevieria in Florida.
Reference: (1) M. Nakamura et al. J. Gen. Plant Pathol. 72:253, 2006.
