First report of tomato anthracnose caused by Colletotrichum boninense in Malaysia.

Abstract

In May, 2013, severe anthracnose symptoms were observed on the leaves of tomato plants grown in the Cameron Highlands (Pahang, Malaysia). The disease incidence reached 40% on mature leaves. Typical symptoms included circular, immersed lesions with orange spore masses in a dark centre. When grown on potato dextrose agar at 25°C with a 12 h photoperiod, colonies of a fungus isolated from symptomatic leaves were cream-to-orange coloured. These morphological characteristics are consistent with the description of Colletotrichum boninense (Moriwaki et al., 2003). Conidia measured 12.5-15.5×4.6-5.1 μm, were generally cylindrical, had obtuse ends and a hilum-like low protrusion at the base. Conidial length/width ratio was 2.8 to 3.0. The internal transcribed spacer RNA region was sequenced (GenBank accession No. KM039057.1) and proved 99% similar to that of C. boninense accession no. KJ619456.1. Tomato plants were inoculated with 40-μl droplets of a conidial suspension (105 conidia/ml) onto the surface of wounded and non-wounded leaves, using a sterilized hypodermic needle and were then kept in a moist chamber for seven days at 25°C with a 12-h photoperiod. Sterile distilled water was used for inoculating the leaves of control plants. Leaves inoculated with the pathogen showed symptoms similar to those observed in the field within 3-6 days, while no symptoms were present on controls. To the best of our knowledge, this is the first report of C. boninense infecting tomato in Malaysia.