In-Vitro Management of Erwinia Carotovora the Causal Organism of Potato Soft Rot Disease
Abstract
In vitro efficacy six chemical substance were evaluated against Erwinia carotovora the causal organism of potato soft rot disease. E. carotovora was isolated from diseased potato tubers by dilution plate technique and different biochemical and pathogenicity test were performed to confirm the bacterial species. Six chemicals viz. Copper Oxychloride @ 0.2%, Mancozeb @ 0.2%, Boric acid @ 0.1%, Kasugamycin @ 0.02%, Carbendazim @ 0.3% and Sodium Hypochlorite @ 0.2% were tested against E. carotovora subsp. carotovora by well diffusion method. For each treatment there were four replications and tested chemical volume was 100 µl. Data were recorded up to five days of incubation. Maximum zone of inhibition (mm) was obtained after 48 hours of incubation with Copper Oxychloride (30.35 mm), followed by Mancozeb (20.15 mm), Boric acid (19.15 mm) and Kasugamycin (16.28mm). Copper Oxychloride produced the maximum growth inhibition (33.72%) of the pathogen, on the other hand Sodium Hypochlorite (2.68%) did not efficiently inhibit the growth of E. carotovora. Copper Oxychloride proved to be the best chemical followed by Mancozeb under in-vitro management against E. carotovora subsp. carotovora.
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Introduction
Potato (Solanum tuberosum L.)is a starchy tuber crop belongs to the family Solanaceae. Potato possess number four position food crop after wheat, maize and rice in the world (Douches et al., 1996) [1]. In Bangladesh the average yield of potato has been estimated 82, 05, 470 metric tons in the year 2011-2012 (BBS, 2012) [2]. Still potato production is quite low in comparison to that of the leading potato growing countries of the world.
Among many pathogenic bacteria E. carotovora subsp. carotovora causing potato soft rot disease is considered as most important disease (Akbar et al., 2014) [3]. It is an important post-harvest disease which cause huge losses in stored potatoes if not properly managed. It has been estimated that every year 22% of potatoes are lost due to fungal, viral and bacterial diseases and pests, which is comparable to a yearly loss of more than 65 million tones and bacterial soft rot contributes it as much as 50% alone of the total potato production (Czajkowski et al., 2011) [4]. The effect of soft rot disease is more prominent in the countries where suitable storage facilities are insufficient.
Generally chemical substances are not prescribed for the management of bacterial disease because it has high chance of lingering issue on human wellbeing and negative impression on the environment. However, many researchers evaluated various chemicals in order to control the soft rot bacteria. Copper-based compounds were found more effective against E.carotovora among numerous chemicals in-vitro (Rashid et al., 2013) [5]. Acetic acid, boric acid and bleaching powder considerably reduced the infection rate, loss in weight and percentage of disease reduction against E. carotovora subsp. carotovora (Rahman et al., 2017) [6]. The antibiotics had a substantial effect on plant pathogenic microorganisms which formed cell wall degrading enzymes (Alice and Sivaprakasam, 1995) [7].
Considering the great economic losses, the present investigation was undertaken to isolate and identify of causal organism and to evaluate the efficacy of six different chemicals against E. carotovora subsp. carotovora under in-vitro condition.
Conclusion
Bacteria can multiply very fast and produce disease in favorable condition and the most serious aspect is that there are hardly any prospects to manage bacterial pathogens on potato. Employ of chemical substance free from health risk can be conducive and suitable way to manage potato soft rot disease. Among the chemicals tested in this experiment Copper oxychloride @ 0.2% was found most effective against the bacteria, other chemicals also had moderate effect against this bacterium in vitro. A through and large-scale research is required to find out an effective method to control soft rot of potato.
