Fire blight, affecting more than one hundred and thirty species in the Rosaceae, is probably the most destructive disease affecting pear and apple cultivars in many countries. Currently, there are no effective synthetic compounds with systemic properties. Other major problem is the occurrence and spread of strains of Erwinia amylovora with resistance to streptomycin and copper. Taken into consideration the human and environmental health, the use of biocontrol agents either as an alternative or as a supplement within an integrated fire blight management strategy has attracted worldwide attention. In this study, E. amylovora solution of 107 CFU ml-1 was treated with bio-control agents, Bacillus subtilis str. QST 713, B. amyloliquefaciens str. MBI 600 and their mixture (at solution densities of 106, 107 and 108 CFU ml-1 for each one) on Petri dishes, containing King’s B medium and, compared with positive (streptomycin sulphate) and negative (sterile distilled water) controls. In vivo studies were performed on two-year-old apple cv. Gala seedlings grown in 45-cm-diameter pots containing a sterilized mix of soil–sand–peat under controlled greenhouse conditions (85% relative humidity, 25°C temperature and 16h of day light). The plants were irrigated as needed by drip-irrigation and each pot received a mineral solution (NPK: 20–20–20) at 2 g l-1 twice. When plant shoots reached a length of 30-35 cm, bio-control agents, individually and their mixture, were applied to the plants by a hand-sprayer. Obtaining the data, 108 CFU ml-1 of Bacillus spp. suspension mixture showed strongest in vitro antibacterial effect (26mm) among the tested treatments after positive control streptomycin (28.6mm). Parallel to in vitro findings, the mixture was most effective against the pathogen on cv. Gala (66.03%). Findings show that the use of mixture of beneficial microorganisms with individual antagonistic properties against the pathogen can be an effective strategy as a natural alternative to agrochemicals in the scope of good agriculture practices.
Abstract:Loquat is attacked by many phytopathogenic fungi.Among these Spilocaea pyracanthae is of economic importance. . In KPK, it is mainly cultivated in Mardan, Peshawar and Hari Pur districts while, in Punjab, it is mostly grown in the Pothowar region (Hussain et al. 2007). Loquat leaves have great significance from medicinal and nutritional point of view. In China, loquat leaves are being used as folk medicine for the treatment of pulmonary tuberculosis (Zhang et al. 2004). Loquat leaves are also used to cure various skin diseases, pain, inflammation, coughing, diabetes and liver disorders (Nishioka et al. 2002;Hamada et al. 2004;Sakuramata et al. 2004).There are numerous pathogens that attack loquat. Fire blight caused by Erwinia amylovora is a serious bacterial disease of loquat (Seymour 1965). Leaf spot incited by Diplocarpon mespili (= Entomosporium mespili) is another important disease of loquat (Batool et al. 2014) and several genera of subfamily Pomoideae of the Rosaceae family. The disease has proved itself capable of rendering an entire fruit crop unmarketable (Davidson 1985). Other pathogens reported to infect loquat include: Pseudomonas eriobotryae (canker), Phytophthora spp. (crown rot), Lasiodiplodia theobromae (= Diplodia natalensis -collar and root rot), and Colletotrichum gloeosporioides (anamorphic Glomerella) (anthracnose) (Crane and Caldeira 2006).Loquat scab is a very common disease in the Southern Italy, especially in Sicily, South Africa, around the Mediterranean basin, and in the eastern regions of North America on different hosts (Gardner and Raabe 1966;Raabe and Gardner 1972; Butt et al. 2015). Very little information is available in literature regarding loquat scab and the associated fungus Spilocaea pyracanthae. The fungus was first reported on loquat in 1909 (Smith 1909). The disease resembles pear and apple scabs in all aspects caused by Venturia pirina and V. inaequalis, respectively (Ohlendorf 1999). Loquat is highly susceptible to leaf and fruit scab especially during wet seasons when control measures are inadequate. Scabbed fruit is rendered unsuitable for market and results in economic loss (Tous and Ferguson 1996;Caballero and Fernández 2004). In Pakistan loquat is a neglected fruit tree and no attention has been paid to fungal pathogens associated with it. The current study is focused on the symptomatology of During extensive surveys of loquat orchards in 2013, spots were observed on leaves. The spotted leaves were brought to the laboratory for identification of disease symptoms and the associated pathogen. The color and shape of the spots were observed. For isolation of the pathogen, the spots were cut, and the surface was sterilized in ethanol and plated on autoclaved Potato Dextrose Agar (PDA) in 90 cm Petri plates. The plates were then incubated at 25 °C for the growth of the fungus. The fungus was purified from a single spore and identified on the basis of morphological characters (Schubert et al. 2003;Schubert and Braun 2005).The pathogenicity of the fungus was conf...
Carrot (Daucus carota L.) is among the most economically important vegetable crops worldwide. Seedborne bacterial pathogens of carrot cause important damages to seed quality and yield of plants. In this study, seedborne bacteria were determined on some carrot seeds sown in Turkey. Seeds of different orange and black color varieties of carrot were collected from Eregli and Kasınhanı districts of Konya province, where the highest carrot production is reported. Subsamples of 10,000 seeds were soaked in 100 ml sterile saline (0.85% NaCl) with 0.02% Tween 20 overnight at 5 °C, YDCA, KB, MKM, MD5A and mTBM media were used for bacterial isolation and bacterial morphological characterization. Biochemical, physiological and molecular methods were used for the identification of the bacterial isolates. Pathogenicity tests of strains were performed on orange color carrots, and pathogenic strains induced a hypersensitive reaction in tobacco plants. The 60 pathogenic and saprophytic bacterial strains were obtained belong to Pseudomonaceae, Bacillaceae, and Xanthomonadaceae families. There were twenty-three seed samples on 5 different orange carrot cultivars Maestro, Bolero, Sireco, Natuna and Romans, and 11 black carrot genotype of traditional cultivar ‘Eregli’. Two pathogenic bacteria were defined as Xanthomonas hortorum pv. carotae and Pseudomonas viridiflava at different percent infestation ratios (17.39-18.18%) and (9.09-13.04%) on orange and black carrot seed samples. To the best of our knowledge, it is the first report of P. viridiflava on carrot seeds in Turkey.
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