Potential of Streptrol and Oxolinic Acid Bactericides to Controlling Potato Erwinia Soft Rot Bacteria and their Secondry Effects on Growth, Yield and Tubers Quality

Abstract

Two successive experiments were conducted. The first was laboratory experiment to examine the best bactericidal effect of streptrol and oxolinic acid according to the inhibition zone on different 10 isolates ofErwiniacarotovora subsp. carotovora. The results showed that the concentration of 100 ppm of each streptrol or oxolinic acid gave the highest inhibition zone with significant superiority of streptrol over oxolinic acidwith percentage estimated by 30.49%. The erwinia isolates E 2 and E 5 were found to be the most sensitive; while, the isolates of E 7 and E 9 were the most resistance regardless the used bactericides according to their inhibition zones. The second experiment was conducted in the greenhouse to study the effect of streptrol and oxolinic acidwith 100 ppm on potato plant infected with each of E 2 , E 5 , E 7 and E 9 erwinia isolates, in addition to uninfected potato to study the secondary effects of the applied bactericides on the growth, yield and tubers quality of the treated potato plants. The greenhouse experiment revealed that the erwinia isolates of E 7 and E 9 caused more significant reduction of the studied parameters compared with the isolates of E 2 and E 5 , in 2015-2016 seasons. Also, the using of streptrol in concentration of 100 ppm gave the most bactericidal effect regardless the used erwinia isolate. In addition, the results showed that each of streptrol or oxolinic acid did not show any significant secondary effect s on all studied characters except shoot fresh weight, in both seasons of study.