First report of rust disease caused by Puccinia linkii on Viburnum edule in Turkey

During surveys conducted on Viburnum edule in 2003, severe symptoms of a rust disease were observed on many trees from late spring through the summer in Sanlıurfa, southeastern Anatolia district of Turkey. Symptoms, first observed in spring on leaves and some fruits, became more sever throughout the summer season, with infected leaves dying prematurely. Early symptoms of the infection were the presence of small, light foliar lesions. Initially, these foliar lesions were 0.5mm to 3mm in diameter, generally oval to round, eventually coalescing into 2 to 8mm diameter irregular shaped lesions. Profuse numbers of urediniospores were produced from uredinium within the symptomatic tissues. Urediniospores were colourless, round to obovate or to some extent pyriform, 14-20µm in diameter. Production of teliospores and mesospores was noted during late summer and autumn. Mesospores were 21- 26µm, pyriform, some with pedicels, 5-8µm in length. Teliospores ranged from light-brown to dark-brown in colour, 33-46µm long and 18-24µm across. No prominent was present at the top of the teliospores but the wall was thicker in comparison to the edges. Based on morphological characters described above, this rust pathogen was identified as Puccinia linkii (Klotzsch, 1833).

Urediniospores harvested from infected leaves were suspended in 100ml of water, containing one drop of Tween-20 and 5.0 g of talcum powder, and used to spray-inoculate three one-year old healthy nursery plants at a rate of 10⁵ urediniospores per ml. Plants were placed in a moist chamber (100 % RH) for 16h at 18 ± 1°C. After inoculation, plants were covered with a plastic bag for 48 hours. The chamber was then partially opened and plants allowed to slowly dry before placing them on a bench in a greenhouse at 22 ± 2°C. Control plants, sprayed with sterile water, were treated as described above. After 3 weeks, inoculated plants showed lesions similar to those observed on trees in Sanlıurfa. The control plants remained healthy.

This is the first report of P. linkii on V. edule in Turkey. The disease was previously reported on same host in northern British Columbia, Canada (Haeussler & Coates, 1986).