First Report of Root and Crown Rot of Almond Caused by Phytophthora spp. in Turkey

Abstract

Almond (Prunus dulcis) production is currently increasing in Turkey. Losses of approximately 1% associated with root and crown rot of almond seedlings were observed in two commercial nurseries in Ankara and Düzce provinces in 2009. Aboveground symptoms were leaf chlorosis and wilt. Feeder roots were decayed, necrosis occurred on taproots and basal stems, and plants collapsed within several weeks. Roots were washed in tap water and 9 to 10 pieces (3 to 5 mm long) of root tissue taken from the margins of canker lesions, without surface disinfection, were placed on selective medium P5ARPH-CMA (2). Plates were incubated for 3 to 5 days at 20°C in darkness and a number of Phytophthora spp. were recovered. Actively growing mycelium was transferred to carrot piece agar containing β-sitosterol (per liter: carrot piece, 40 g; agar, 20 g; β-sitosterol, 20 mg). Isolates were identified as Phytophthora cactorum and P. citrophthora on the basis of morphological characteristics (1). P. cactorum produced abundant sporangia, oogonia, and paragynous antheridia on carrot piece agar plus β-sitosterol. It had conspicuously papillate and caducous sporangia with short pedicel. Sporangia were usually ovoid but sometimes nearly spherical. P. citrophthora did not produce sexual structures in single culture. It produced papillate, noncaducous sporangia, which were usually ovoid and obpyriform, often asymmetrically shaped and rarely possessed more than one apex. P. citrophthora did not grow at 35°C but it grew well at 30°C. Isolate identities were confirmed by sequence analysis of the ribosomal DNA internal transcribed spacers 1 and 2 (GenBank Accession Nos. HM357622, HM357623, HM357624, HM357625) using primers ITS1 and ITS2 (3). One representative isolate of each species was used to inoculate eight 2-year-old almond plants with an agar plug with actively growing mycelium that was attached to exposed cambium of basal stems. Agar plugs without mycelium were used for eight control plants. All plants inoculated with Phytophthora spp. collapsed within 3 to 4 weeks. Control plants remained healthy. Phytophthora spp. were reisolated from necrotic basal stems. To our knowledge, this is the first report of P. cactorum and P. citrophthora of almond in Turkey. References: (1) M. E. Gallegly and C. Hong. Phytophthora, Identifying Species by Morphology and DNA Fingerprints. The American Phytopathological Society, St. Paul, MN, 2008. (2) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986. (3) S. G. Roy et al. J. Phytopathol. 157:666, 2009.

First report of Phytophthora megasperma causing crown and root rot of almond in Turkey

“…In Turkey, some Phytophthora spp. such as P. cactorum, P. citrophthora and P. niederhauserii have been reported previously on almonds (Kurbetli & Değirmenci 2010; 2011) but this is the first report of Phytophthora megasperma causing crown and root rot of almonds in Turkey.…”

Phytophthora citrophthora, a new pathogen causing decline on horse chestnut in Turkey

“…2009). In Turkey, it is endemic as a major pathogen of citrus (Güncü 1989) and has been found on other hosts such as almond (Kurbetli and Değirmenci 2010) and kiwi fruit (Akıllı et al. 2011), suggesting that it may potentially spread efficiently in Turkey.…”

Involvement of Phytophthora citrophthora and Phytophthora nicotianae in severe decline and gummosis of grapefruit (Citrus x paradisi Macfad.) in southern Türkiye

“…papaya, pear, persimmon, pistachio, stone fruits (almond, apricot, cherry, peach, plum) and walnut, as well as citrus species (Erwin & Ribeiro, 1996). This pathogen was previously reported in several fruit orchards and nurseries to cause root and crown rot on almond and kiwifruit as well as shoot blight on kumquats (Citrus japonica) in Türkiye (Akıllı et al, 2011;Kurbetli & Değirmenci, 2010;Kurbetli, Sülü, et al, 2016).…”