An Outbreak of Bacterial Speck Caused by Pseudomonas syringae pv. tomato on Tomato Transplants Grown in Commercial Seedling Companies Located in the Western Mediterranean Region of Turkey

Abstract

A serious outbreak of a leaf spot disease was observed on tomato transplants grown in commercial seedling companies in southwestern Turkey (Antalya) during the springs of 2002 and 2003. Disease incidence was more severe in the western Mediterranean Region of Turkey. Occurrence of the outbreak resulted in approximately 20 and 25% seedling losses in the springs of 2002 and 2003, respectively. The initial symptoms consisted of pronounced water-soaked, dark brown-to-black spots on young expanding leaves that were 1 to 2 mm in diameter. Later, a number of leaf spots on older leaves enlarged and coalesced, causing leaf desiccation and finally, seedling death. In addition, in 2003 the disease incidence was approximately 5% in 142 commercial greenhouses. Tomato production was unaffected since significant outbreaks did not occur on greenhouse plants. No fruit symptoms were observed. Twenty-six strains were isolated from diseased tomato seedlings and plants from different greenhouses located in different places and all were gram negative and fluorescent on King's B medium. All strains were levan and gelatin liquefaction positive and oxidase and arginine dihydrolase negative. None of the 26 strains utilized erythritol and l-lactate as the sole carbon source (1,2). Fatty acid analysis identified the strains as Pseudomonas syringae pv. tomato with similarity indices ranging from 0.876 to 0.932%. Pathogenicity of the isolates was confirmed on 4-week-old tomato seedlings (cv. Biotek Selin) sprayed with the bacterial suspensions containing 108 CFU/ml of sterile water. Later, a number of leaf spots on the leaves enlarged and coalesced, causing leaf desiccation. Inoculated and control tomato seedlings were covered with polyethylene bags and placed in a growth chamber at 25°C for 48 h and then the bags were removed. Small (1 to 2 mm), water-soaked, dark brown-to-black spots similar to those observed in the greenhouses of commercial seedling companies and commercial greenhouses that produce tomato developed on the young expanding leaves of inoculated plants within 7 to 10 days. No symptoms developed on control plants. The bacterium was reisolated from inoculated plants and identified as a strain of Pseudomonas syringae pv. tomato. Koch's postulates were fulfilled. To our knowledge, this is the first report for the occurrence and outbreak of the bacterial speck disease on tomato transplants in greenhouses of commercial tomato seedling production companies in Turkey. References: (1) D. C. Hildebrand et al. Pages 60–80 in: Laboratory Guide for Identification of Plant Pathogenic Bacteria. N. D. Schaad, ed. The American Phytopathological Society, 1988. (2) J. B. Jones et al. Plant Dis. 70:151, 1986.

A Review of the Most Common and Economically Important Diseases That Undermine the Cultivation of Tomato Crop in the Mediterranean Basin

“…Portugal, Spain, France, Italy, Greece, Turkey, Israel, Lebanon, Tunisia, Morocco 75 [40,41] Decrease at high T (28 • C) [42]; Decrease at high CO 2 (800 ppm) [43] Increase with high RH [40] Phytoplasma Candidatus Phytoplasma solani Stolbur Spain, France, Italy, Greece, Albania, Montenegro, Croatia, Turkey, Israel, Lebanon, Syria 80 [5,44] n.a. Increase with high RH [45] [46,47] Increase at medium to high T [48] n.a.…”

“…Pst is favoured by a temperature range of 13-28 • C, with a high humidity and even with free water on leaves [40]. Bacterial speck outbreaks may cause 20-25% seedling losses, while tomato yield losses may reach 75% in case of early-infection [40,41].…”

Sensitivity of tomato (Solanum lycopersicum) cultivars from Turkey to bacterial speck (Pseudomonas syringae pv. tomato)

“…The outbreak in 2003 caused an approximate 5% loss in 142 commercial greenhouses in the region. The greenhouse tomato production was not affected by the epidemic and disease symptoms on the fruit were not observed (Basim, 2004).…”

“…Origin Reference 0853-td1 Turkey Basim et al, 2004 0843-td5 Turkey Basim et al, 2004Basim et al, 2533 Turkey Basim et al, 2004 0433-td28 Turkey Basim et al, 2004 0433-td31 Turkey Basim et al, 2004Basim et al, 1033 Turkey Basim et al, 2004Basim et al, 1833 Turkey Basim et al, 2004Basim et al, 1833 Turkey Basim et al, 2004Basim et al, 2943 Turkey Basim et al, 2004 0143-td47 Turkey Basim et al, 2004Basim et al, 1933 Turkey Basim et al, 2004 0753-td50 Turkey Basim et al, 2004Basim et al, 1153 Turkey Basim et al, 2004Basim et al, 1434 Turkey Basim et al, 2004Basim et al, 1434 Turkey Basim et al, 2004Basim et al, 2034 Turkey Basim et al, 2004 0504-td4 Turkey Basim et al, 2004Basim et al, 1044 Turkey Basim et al, 2004Basim et al, 1044 Turkey Basim et al, 2004 (Psallidas, 1988). The first determination of this disease in Turkey was made by Saygili (1975) in the Aegean region and Cinar (1977) in the east Mediterranean region.…”

“…The first determination of this disease in Turkey was made by Saygili (1975) in the Aegean region and Cinar (1977) in the east Mediterranean region. The bacterial speck disease in the western Mediterranean region has occurred in commercial vegetable seedling production companies and caused great seedling losses, as reported by Basim et al (2004).…”