First outbreak and occurrence of citrus blast disease, caused by Pseudomonas syringae pv. syringae, on orange and mandarin trees in Turkey

Abstract

In the spring of 2004, severe outbreaks of a disease resembling citrus blast (Whiteside et al ., 1988), were observed on trees of orange ( Citrus cinensis cv. Washington) and mandarin ( Citrus rediculate cv. Marisol) in the Turkish Mediterranean regions of Adana and Antalya. Characteristic disease symptoms were first seen on leaves as watersoaked lesions and black areas on the petiole wings. Later lesions extended to the mid-vein of leaves and to the twigs surrounding the base of the petiole. Finally, the leaves dried and rolled, while still firmly attached, before eventually dropping without petioles. The necrotic areas on twigs further enlarged and the twigs were eventually killed within 20 -30 days. The damage was serious in a 50-hectare citrus orchard in Antalya, with a disease incidence of nearly 100%. Twelve isolates of a bacterium, consistently isolated from infected leaves, petioles and twigs, which formed fluorescent colonies on King's medium B, were purified and used for further studies. All isolates were Gram-, oxidase-, pectolytic activity-, starch hydrolase-, arginine dihydrolase-and nitrate reduction-negative; and levan-, gelatin hydrolase-positive. They produced hypersensitive reactions (positive) on tobacco leaves ( Nicotiana tabacum cv. Samsun N.). All produced acid from glucose, glycerine, arabinose, mannitol, sorbitol, sucrose and xylose but not from lactose and maltose. The test results conformed to the characteristics of P. syringae pv. syringae (Braun-Kiewnick & Sands, 2001) as the causal organism of citrus blast and were similar to those of reference strain NCPPB 2307 of P. syringae pv. syringae used in this study. Fatty acid analysis (Atatürk University, Erzurum, Turkey) confirmed the bacterial strains as P. syringae pv. syringae with similarity indices of 81-94%.Pathogenicity of the strains was tested on 1-year-old mandarin. Inoculations were made, using a hypodermic needle with a suspension of bacteria in a saline buffer (10 8

Phenotypic and genetic characterization of Pseudomonas syringae strains associated with the recent citrus bacterial blast and bacterial black pit epidemics in Tunisia

“…Similar surveys, reported by Mirik et al . () in the Turkish Mediterranean regions of Adana and Antalya, revealed severe outbreaks of the disease on trees of orange ( C . sinensis ‘Washington navel’) and mandarin ( C .…”

“…limon ‘Eurêka’) in the field. Samples of different organs showing symptoms of blast and black pits, as reported in the literature (Mirik et al ., ), were cut, put separately into sterile plastic bags and transported to the laboratory. In addition, one plant sample from almond ( Prunus amygdalus ) showing shot hole symptoms on leaves, bacterial exudation and twig dieback, was also processed.…”

“…Subsequently, Coit () described a new disease of orange that was called citrus blast. More recently, citrus blast of orange and mandarin has been reported from Turkey (Mirik et al ., ) and Iran (Beiki et al ., ). According to these studies, characteristic symptoms on leaves consist of water‐soaked lesions and black areas on the petiole wings that subsequently extend to the mid‐vein and to the twigs surrounding the base of the petiole.…”

“…Subsequently, Coit (1916) described a new disease of orange that was called citrus blast. More recently, citrus blast of orange and mandarin has been reported from Turkey (Mirik et al, 2005) and Iran (Beiki et al, 2016). According to these *E-mail: abd_emna@yahoo.fr…”

“…Finally, the leaves dry and roll, while still firmly attached to the tree, before eventually dropping without petioles. Typical symptoms on fruits consist of necrotic spots occasionally surrounded by a chlorotic halo (Mirik et al, 2005;Beiki et al, 2016).…”