Research Information System
Plant Disease, vol.100, no.1, pp.227, 2016 (SCI-Expanded)
During June 2012, 5-year-old pomegranate plants (Punica granatum L.) growing in Şanlıurfa province located in the Southeast Anatolia Region of Turkey showed bark cracks on stems just above the soil, brown lesions on root collars just below the soil line, no capillary root formation, and softening and rotting of the main stem with a sour smell. Crown and root samples from 15 pomegranate plants exhibiting symptoms were cultured on Phytophthora-selective medium of grated apple corn meal agar (GACMA) (Türkölmez et al. 2015) amended with pimaricin, ampicillin, rifampicin, and pentachloronitrobenzene. Papillated, ellipsoidal sporangia with short pedicels (2.5 to 5 μm) were 25.0 to 39.5 μm in breadth and 34.5 to 65.0 μm in length) and formed on sympodial sporangiophores. Chlamydospores were 23.0 to 42.5 μm in diameter. The minimum, optimum, and maximum temperatures for mycelium growth on potato dextrose agar were 11°C, 27°C, and 33°C, respectively. Isolates were identified as Phytophthora palmivora (E. J. Butler) E. J. Butler according to the descriptions of this species (Erwin and Ribeiro 1996). The ITS region of rDNA amplified using ITS6/ITS4 primer pair of one isolate (GenBank Accession No. KP985657) was sequenced and compared with corresponding sequences in GenBank and Phytophthora-ID databases by BLAST analysis. These sequences showed 99 to 100% identity with those of P. palmivora isolates. Pathogenicity tests were carried out on ten 1-year-old plants of pomegranate cv. ‘Hicaz’ grown in 5-liter pots in a screen house with temperatures ranging from 20 to 30°C by placing ten mycelial plugs of a 1-week-old culture grown on GACMA around the primary roots of each plant after removing 10 to 15 cm of soil around the stem of the plant. Root parts were covered with soil and kept saturated by watering plants daily as required. Control plants were inoculated with plugs of sterile GACMA. All inoculated plants declined after a month similar to the ones observed in the orchard. P. palmivora was reisolated from root tissues of inoculated plants. No symptoms were observed on the controls. P. palmivora has been reported causing fruit rot of pomegranate in India (Erwin and Ribeiro 1996). Pomegranate is an important fruit because of its potential health benefits and crown and root rot caused by P. palmivora might be a risk for pomegranate production.