Bacterial canker is an economically important disease of tomato. Resistance induced by DL-b-Amino butyric acid against bacterial canker caused by Clavibacter michiganensis ssp. michiganensis in tomato plants was investigated. Different doses of DL-b-Amino butyric acid (250-1000 lg ml )1 doses) were tested on 3-week old plants inoculated with a 10 8 CFU ml )1 bacterial suspension, and disease development was evaluated after inoculation and treatment. Although in vitro growth of the bacteria was not affected by DLb-Amino butyric acid treatment, foliage sprays of 500 lg ml )1 DL-b-Amino butyric acid significantly suppressed disease development up to 54% by day 14 after inoculation at the four different doses tested. Bacterial populations were reduced by 84% in BABA-treated plants compared to water-treated plants by day 4 after inoculation. Inoculated BABA-treated plants showed significantly higher phenylalanine ammonia-lyase activity, peroxidase activity, and H 2 O 2 concentration than inoculated water-treated plants during day 1 after treatment. These findings suggest that the DL-b-Amino butyric acid treatment resulted in an increase of these enzymes and in H 2 O 2 concentration in planta, and was associated with induction of resistance to bacterial canker.

Turkey is one of the world's largest producers and exporters of table grapes. Growing social concerns over excessive pesticide use have led to farming to move from conventional to organic practices. Table grapes were collected from 99 different farms in three Aegean regions. Pesticide residues were only detected in farms using conventional agriculture practices while no pesticides were detected in grapes from farms using organic or integrated pest management. A risk assessment model indicated that lambda-cyhalothrin posed the most significant risk at conventional farms.

Plants have evolved different but interconnected strategies to defend themselves against microbial pathogens and stress conditions. The defense responses of tomato (Lycopersicon esculentum Mill) seedlings treated with DL-b-aminobutyric acid (BABA) were investigated with and without abiotic stress (100 mM NaCl) against bacterial speck disease caused by Pseudomonas syringae pv. tomato. The plants were sprayed with 50, 125, 250 or 500 mg ml 21 BABA and were inoculated with 10 8 colony-forming units ml 21 bacterial suspension 1 day after treatment. Abiotic stress led to an increase in plant resistance. When BABA was additionally applied as a foliar spray at 125 mg ml 21 , the effect on plants was almost identical to that on plants that were sprayed with BABA at 500 mg ml 21 alone. The bacterial multiplication in the plants was 250-fold lower than in the water-treated (control) plants and in plants that were sprayed with 500 mg ml 21 BABA alone within 48 h postinoculation (hpi). Physiological studies were carried out in the plants treated with BABA in order to investigate the reason for this synergistic effect. Abiotic stress with BABA spray resulted in high H 2 O 2 generation and guaiacol peroxidase activity in the plants. The activity of the enzymatic antioxidative protective system of the plants, superoxide dismutase, ascorbate peroxidase and catalase (CAT), also showed a significant delayed increase in BABA-treated plants under abiotic stress conditions. These increases in enzyme activity coincided with the initiation of the most suppressive effect of BABA on bacterial growth by 24 hpi, which were significantly higher than the control. Salt stress alone did not lead to any significant increase in CAT activity, but salt stress with BABA did. These findings indicate a synergistic effect between salt stress and BABA at low concentrations, resulting in induced plant resistance. Furthermore, a stress regulation effect of BABA under abiotic stress can be associated with plant resistance.

Dried grapes make the ideal low-calorie snack. The formation of gray mold during the drying of the grapes can severely decrease production. Pesticides and fungicides are applied to prevent losses due to pests and mold. Dried grapes from 99 farms in the Aegean region were sampled for pesticide residues. Of the 26 pesticides analyzed for, chlorpyrifos methyl, chlorpyrifos ethyl, deltamethrin, lambda-cyolathrin, dichlofluanid, iprodione, and procymidone were detected in the dried grapes. Only seven samples contained residues above the maximum residue limit. It is important to note that pesticide residues were only present in samples originating from vineyards using conventional farming practices.

In the spring of both 2003 and 2004, serious outbreaks of a suspected bacterial leaf spot disease were observed on tuberous non-stop begonia plants ( Begonia × tuberhybrida cvs. Futta, Kleo, Apricot and Red) and strawberry begonia ( Saxifraga sarmentosa ) grown for potted production in commercial greenhouses located in Adana, Manisa, Yalova and Istanbul provinces of Turkey. The initial symptoms of the disease were small round spots and angular necrotic areas on leaf surfaces. A general leaf yellowing and necrosis followed the spotting. Defoliation, open stem canker and vascular discoloration were observed on plants in advanced stages of the disease. Disease incidence was recorded in the range of 15-30% over two years. Isolations were made from leaves and stems of the affected plants on yeast dextrose chalk agar producing yellow-coloured mucoid and convex colonies. Eighteen bacterial isolates were purified and used for further studies. All isolates were characterized as non-sporing, Gram negative, rodshaped, motile, aerobic, oxidase-negative, catalase-positive and amylolyticpositive (Schaad et al ., 2001) and all were identified as Xanthomonas axonopodis pv. begoniae (Xab; Vauterin et al ., 1995) based on fatty acid methyl ester analysis (Yeditepe University, Istanbul, Turkey) with similarity indices ranging from 51 to 77% (Chase et al ., 1992) and indirect-ELISA tests (Agdia BRA 23700) (Benedict et al ., 1990). All of the test results were similar to those of the reference strain used in this study.Pathogenicity was confirmed by spray inoculation of the leaves on tuberous begonia and strawberry begonia plants. Sterile distilled water and a reference strain (BPIC 2013, X. axonopodis pv. begoniae ) were used as negative and positive controls respectively. All plants were covered with polyethylene bags for 48 hour at 25 ° C. After inoculation, water-soaked and necrotic symptoms were observed on tuberous and strawberry begonia plants within 5-7 days. No symptoms were observed on control plants. This is the first report of Xab in commercial floriculture in Turkey and also the first report of infection of strawberry begonia by this pathogen.