First report of Fusarium proliferatum causing crown and root rot of Asparagus officinalis in Turkey.

Abstract

In 2011, crown and root rot symptoms appeared on 3to 8-month-old asparagus plantations in different production areas located in the Gonen district of the Balikesir province (Turkey). The symptoms included a decrease in the yield of spears and brown lesions, vascular discoloration and rot of roots, rhizomes, and stems. The disease emerged on new plantings which were established with propagation materials from infected fields. Disinfected root pieces were placed on potato dextrose agar medium and incubated at 23±1°C. Fusarium-like colonies were obtained and identified based on cultural and morphological characteristics (Leslie and Summerell, 2006). Microconidia, borne in long and short chains and false heads, were abundant, single-celled, oval, and ranged from 3.1 to 3.7×5.6 to 8.1 μm. Macroconidia were 3-5 septate, slightly curved, and ranged from 3.7 to 5.0×33.7 to 40.0 μm. The identification of the causal fungus as F. proliferatum first based on morphological data, was confirmed by speciesspecific PCR assays using the primer set CLPRO1/2 which amplified the expected 526-bp DNA fragment (Mule et al., 2004). To fulfill Koch’s postulates, pathogenicity tests were performed using a pot culture inoculation method. Sandcorn meal mixture was inoculated with plugs from F. proliferatum, incubated at 23±1°C for 10 days, then mixed with 1 kg autoclaved soil. Healthy 45-day-old asparagus seedlings were transplanted into inoculated pots and grown for 45 days at 23±1°C with 14 h photoperiod. Infected plants showed typical brown lesions in the root system, from which F. proliferatum was reisolated. This is the first report of F. proliferatum causing crown and root rot on asparagus in Turkey.