Abstract

Bacterial soft rot caused by Pectobacterium carotovora subsp. carotovora (previously called Erwinia carotovora subsp. carotovora) is a major bacterial disease infecting almost all vegetable species having fleshy storage organs including potato. Management of post-harvest bacterial soft rot by chemicals can lead to severe health issues. During this present study, attempts were made to use aqueous Christmas melon (Laganaria breviflorus) fruit extract for the management of bacteria soft rot. The experiment was carried out in the Pathology Laboratory of the Federal College of Horticulture, Dadin-kowa, Gombe, Nigeria in 2022. The treatments used were the different concentrations of the aqueous Christmas melon fruit extract comprising T₁ (100% concentrated CMFE), T₂ (80% concentrated CMFE), T₃ (60% concentrated CMFE), T₄ (40% concentrated CMFE), T₅ (20% concentrated CMFE), T6 (Control - pathogen only and no treatment). The bacterium was isolated from infected potato tuber and was plated on Nutrient Agar (NA). Pathogenicity test was carried out to confirm the pathogen before the inhibition study and inoculation on the healthy potato tuber. Peeled fruits of L. breviflorus were fermented for seven days in distilled water. Paper discs of 12 mm diameter were impregnated with the extract and placed on the plated pathogen. The plates were arranged on shelves in the incubator and incubated at 27 °C and were observed for up to six days. Similarly, the inoculated tubers were submerged in the aqueous Christmas melon fruit extract of different concentrations for one hour and thereafter dried at room temperature and set in a container. The containers were arranged on shelves in the incubator and incubated for six days at 27 °C. In-vitro results showed that aqueous Christmas melon fruit extract has a low inhibition rate/ effect on the pathogen; it took three (3) days before it could exhibit zone of inhibition. However, among the different levels of concentration of the extract, 100% CMFE exhibited the highest mean diameter zone of inhibition of 29.28 mm (including the disc diameter 12 mm), followed by 80% CMFE with a zone of inhibition of 23.96 mm, followed by 60, 40 and 20% CMFE in decreasing order with zones of inhibition of 19.79 mm, 11.46 mm and 7.29 mm respectively. In-vivo results revealed that L. breviflorus aqueous fruit extracts did not show potential in reducing the severity or protecting the potato against tuber soft rot and therefore cannot be used by farmers to control potato tuber soft rot caused by Erwinia carotovora.

Ivoke, M.A., Abraham, P., Oluro, C.O., 2024. Antibacterial assessment of christmas melon (Laganaria breviflorus) aqueous fruit extract against potato tuber soft rot. Plant Health Archives, 2024, online first.