THE ACTIVITY OF GIBBERELLIC ACID AND CONOCARPUS ERECTUS AGAINST POTATO SOFT ROT DISEASE CAUSED BY ERWINIA CAROTOVORA SUB SP. CAROTOVORA

This study was carried out in order to test the efficacy of C. erectus alcoholic extract and gibberellic acid to control potato soft rot bacterial disease caused by the bacteria type E. c. sub sp. carotovora was investigated. The inhibition ability of the extract at 250, 500 and 1000 ppm concentrations was examined on nutrient agar (N.A) medium. Each concentration was mixed with the medium before solidification then inoculated with the bacterial pathogen. The highest inhibition percentage of Conocarpus was %86.1 at 1000 ppm concentration. In pots experiments, the lowest percentage of infection was %0.00 for tubers treated with 1000 ppm of conocarpus and 1.5g/L beltanol pesticide compared to control which was 41.14%. Whereas inhibition percentages were 6.77, 4.85 and 2.67 respectively, for all three concentration of conocarpus treated in compared to control which was %34.15, in the field experiment Potato grown in pots treated with 500 and 1000 ppm scored the highest tubers weight which were 175 and 154 gm/plant respectively compared with control which was 118.33 gm /plant. While for those grown in the field, tuber treated with beltanol pesticide scored 1197gm/plant highest weight compared to control 248 gm/plant. The highest number of tuber was 27.67 tuber/plant for gibberilin treatment compared to 9.5 tuber/plant for control plants grown in pot. In field experiments, the highest tuber number was 58.33 tuber/plant in potato plants treated with conocarpus at 1000 ppm concentration, compared with control which was 10 tuber/plant. Potato plants treated with 500 ppm conocarpus extract scored the highest branch number which was 6.37 branch/plant compared 2.67 branch/plant for control in pot experiment. While in field experiments, plants treated with concarpus at 500 ppm scored 4.67 branch/plant compared to 1.33 branch/plant in control. The branch lengths were 18.33 cm and 19.67 cm for the plants treated with gibberilin compared to 12.88 and 8.16 cm. for control for pots and field experiments, respectively. The wet and dry weights of root system for potato plants in grown in pots and treated with 1000ppm conocarpus scored 74.2 and 34.48 gm/plant compared to control with 38.1 and 14.2 gm/plant. While in those grown in the field potato plants treated with 500 conocarpus, scored the higest wet and dry weights which were 297,1 and 140.42 gm/plant compared to control 49.1 and 24.87 gm /plant respectively.