Phytophthora cryptogea causing ink disease of Castanea sativa newly reported in Greece
1 NAGREF-Forest Research Institute, 57006 Vassilika, Thessaloniki, Greece
2 Dipartimento di Protezione delle Piante, Università degli Studi della Tuscia, Viterbo, Italy
Accepted: 05 Jan 2010
Ink disease has been associated with Phytophtora cambivora in chestnuts (Castanea sativa) in Greece (Chitzanidis & Kouyeas, 1970; Vettraino et al., 2005). In November 2006, approximately 10% of five to seven-year-old trees in a 0.5 ha orchard in Larissa County, Central Greece, showed disease symptoms including decline of the crown, burrs still remaining on the trees and dark necrosis at the collar with flame-shaped edges (Fig. 1). A Phytophthora species was consistently isolated from collar lesions and soil under symptom-bearing trees onto PARBhy medium (Vettraino et al., 2005) and identified as P. cryptogea Pethybr. & Laffertybased on morphology and cultural characteristics (Erwin & Ribeiro, 1996). Colonies (A2 mating type) appeared fluffy on PDA and did not grow at 35°C. Sporangia were oval to obpyriform, nonpapillate, persistent (32.5-57.5 x 25-35 µm), oogonia smooth, plerotic; antheridia amphigynous, and hyphal swellings produced in abundance. The ITS sequences of five representative isolates were deposited in GenBank: STM(b) and STM(r), from collar tissues; and APA1, ATR1, TSOK1 from soil (Accession Nos. GQ428327, GQ428328, GQ428325, GQ428326, GQ428329, respectively); they were identical to each other and exhibited 100% of identity to that of P. cryptogea isolate EU200283.
Pathogenicity tests of three P. cryptogea isolates (STM(b), ATR1, and APA1) was conducted by soil infestation in a growth chamber at 22o C using twelve three-month-old potted chestnut seedlings for each isolate, and twelve non-inoculated plants as controls. Each seedling was inoculated with 30 ml/l of sterilised soil inoculum, prepared on sterilised millet seeds. All plants were flooded for 24 h twice at two weeks intervals. After five weeks, all post-inoculated seedlings, but not controls, showed crown wilting, collar and root rot symptoms, and P. cryptogea was easily re-isolated (Figs. 2, 3). P. cryptogea has been reported in Greece from almond, daisy, eggplant, cucumber, lupine, alfalfa, Chinese aster (Erwin & Ribeiro, 1996), and sugar beet (Karaoglanidis et al., 2000); and as the chestnut wilt agent in South Australia (Wicks & Volle, 1976). This is the first report of P. cryptogea causing ink disease of chestnut in Greece.
- Chitzanidis A, Kouyeas H, 1970. Notes on Greek speciesof Phytophthora II. Annals of the Benaki Phytopathological Institute (New Series) 9, 267-274.
- Erwin DC, Ribeiro OK, 1996. Phytophthora Diseases Worldwide. St Paul, MN, USA: APS Press, 301-308.
- Karaoglanidis GS, Karadimos DA, Klonari K, 2000. First report of Phytophthora root rot of sugar beet, caused by Phytophthora cryptogea, in Greece. Plant Disease 84, 593.
- Vettraino AM, Morel O, Perlerou C, Robin C, Diamandis S, Vannini A, 2005. Occurrence and distribution of Phytophthora species in European chestnut stands, and their association with Ink disease and crown decline. European Journal of Plant Pathology 111, 169-180.
- Wicks TJ, Volle D, 1976. Phytophthora wilt of chestnuts in South Australia. Plant Disease Reporter 60, 700-702.
This report was formally published in Plant Pathology
©2010 The Authors