Storage Rot of Ginger Rhizomes (Zingiber officinale Roscoe) and their control with African Nutmeg (Monodora Myristica Gaerth) Seeds

Abstract

Ginger grown for its edible rhizome commonly used as spice for food and drinks. It is also known for its medicinal values; however, protecting harvested rhizomes from deterioration is important to enhance storability. Ginger is attacked by fungi which cause destructive storage rot of harvested rhizomes. Effect of storage rots constitute hindrance to meeting current demands for ginger production. Therefore, effect of African nutmeg, (Monodora myristica) for control of fungi causing rot of ginger rhizomes was evaluated. Laboratory studies were carried out, infected ginger rhizomes were sourced from Umudike and Orie-ugba markets; taken to the laboratory for fungi isolation and identification using standard laboratory procedures. In vitro studies of effect of African nutmeg on four fungal species isolated from ginger rhizomes was evaluated. Data collected were analysed using descriptive statistics and ANOVA at α0.05. Fusarium solani, Fusarium oxysporium and Rhizopus oryzae were controlled in vitro and in vivo using crude African nutmeg extract. Fusarium solani, F. oxysporium, R. oryzae and A. flavuswere isolated. Incidence of F. solani was (50-84 %), followed by F. oxysporium (30-78 %), R. oryzae (11-30 %) and A. flavus (3-11 %). F. oxysporium, myelial growth was reduced between 3.33-6.05 %; in the first 4 days after inoculation and 21-30 % to 74.98 % from 5-6 days after inoculation. There is significant difference (P=0.05) in mycelial growth reduction between treated and the control from 5 days after inoculation on the African nutmeg amended PDA. Mycelial growth reductions for R. oryzae decreased with increase in days of incubation. Highest growth reduction (51.67%) was recorded on the first day, while the least (22.14%) was recorded on fourth day. Crude extract of M. myristica considerably reduced growths of fungi studied and could serve as a good safe alternative to chemical fungicides in ginger storage.