Investigation on the Effect of Chemical and Biological Control of Bacterial Soft Root Disease of Potato in Storage.

Abstract

Potato soft rot, caused by Erwiniacarotovora subsp. carotovora, greatly affect potato tuber quality in storage of Egypt and indicated that it can affect all potato cultivars. Erwiniacarotovora subsp. carotovora was isolated from the infected potato tuber and was identified by pathological, morphological and biochemical studies.  One antimicrobialchemical compound chitosans (CS) with concentration (1, 3, 5 %) combine with three biocontrol agents (Bacillus subtilis, Pseudomonas fluorescens and Trichodermavirdi) each. These treatments were screened out in vitro and in storage against the growth of Erwinia carotovora subsp carotovora. All bio-control agents combined with Cs reduced the bacterial soft rot disease to various degrees. The stronger antagonistic activity against Erwinia carotovora was found in treatment Cs 5% with biocontrolagaints (T. virdi, P. fluorescens and B. subtilis respectively). All treatments reduced the soft rot infection to 20-week storage with two types of potatoes (Spunta and Cara) varieties by (91, 86, 83.6 and 77.3% respectively in Spunta c.v.) and (88.6, 86.4 and 79.8% in Cara c.v.). The lowest antagonistic activity against Erwinia carotovora was found in treatment CS 1% with biocontrol agents (T. virdi, P. fluorescens and B. subtilis respectively) varieties by (64.2, 58.6 and 43.7% respectively) compared with the treatments of biocontrol agents individually.

Keywords: Potato - Erwiniacarotovora- Chitosan- T. virdi - P. fluorescens- Bacillus subtilis