ABSTRACT
Studies were undertaken to identify the pathogens associated with rotting of white yam
(.Dioscorea rotundata var. Araba, Asana and Puna) in Ghana, to identify exportable white
yam varieties with superior shelf life and to evaluate the effectiveness of lime and neem
wood-ash in controlling rots in wounded yam tubers.
A field survey was conducted among yam retailers and exporters in Accra. The results
revealed that: a major constraint to yam production and marketing in Ghana is the high
percentage of tuber rot of 10-30% for retailers and 10-40% for exporters; Puna is the
most preferred white yam variety for export and local consumption; Some handling
practices predispose tubers to rot diseases; traditional rot control measures is not widely
practiced; yams shipped abroad are kept in poorly ventilated containers.
Identification of the three yam varieties based on tuber characteristics, showed that the
furrow markings on the corky periderm (skin) of the three white yam varieties are
consistent with variety and therefore a reliable index for their identification.
Isolations made from tubers of the three white yam varieties obtained from three yam
markets in Accra and a yam barn at the Crop Science Department, University of Ghana
Legon, and subsequent pathogenicity studies with the isolates revealed that storage rots
were caused by Aspergillus flavus, Aspergillus niger, Aspergillus oryzae, Botryodiplodia
theobromae, Erwinia carotovora, Fusarium culmorum, Fusarium oxysporum, Fusarium
sp Penicillium brevi-compactum, Penicillium sp., Rhizopus stolonifer and Scutellonema
bradys. This is the first record of the ability of A. oryzae and F. culmorum to cause rot in
yam. Symptoms aiding the identification of A. niger, E. carotovora, P. brevi-compatum,
R. stolonifer and S. bradys are described. Puna had the highest mean frequency of
xi
infection by pathogens (41.9% and 41.3%), followed by Asana (34.4% and 30.7%) and
then Araba (23.7% and 28.0%) in the market and barn respectively. After ten months of
storage Araba had the lowest weight loss of 39.31%, and a lower rotting percentage of
27.5% (P = 0.05). Even though at the 16th week all the yam tubers had sprouted, the rate
of sprouting of Araba was significantly lower (P = 0.05). Lime was significantly more
efficacious in suppressing decay in wounded tubers of the three yam varieties than neem
wood-ash (P= 0.05). Lime also inhibited growth of all the fungal isolates in vitro.
CORNELIUS, E (2021). Causes And Control Of Tuber Rots Of White Yam (Dioscorea Rotumdata Poir Varieties Araba, Asana And Puna). Afribary. Retrieved from https://tracking.afribary.com/works/causes-and-control-of-tuber-rots-of-white-yam-dioscorea-rotumdata-poir-varieties-araba-asana-and-puna
CORNELIUS, ERIC "Causes And Control Of Tuber Rots Of White Yam (Dioscorea Rotumdata Poir Varieties Araba, Asana And Puna)" Afribary. Afribary, 17 Apr. 2021, https://tracking.afribary.com/works/causes-and-control-of-tuber-rots-of-white-yam-dioscorea-rotumdata-poir-varieties-araba-asana-and-puna. Accessed 12 Nov. 2024.
CORNELIUS, ERIC . "Causes And Control Of Tuber Rots Of White Yam (Dioscorea Rotumdata Poir Varieties Araba, Asana And Puna)". Afribary, Afribary, 17 Apr. 2021. Web. 12 Nov. 2024. < https://tracking.afribary.com/works/causes-and-control-of-tuber-rots-of-white-yam-dioscorea-rotumdata-poir-varieties-araba-asana-and-puna >.
CORNELIUS, ERIC . "Causes And Control Of Tuber Rots Of White Yam (Dioscorea Rotumdata Poir Varieties Araba, Asana And Puna)" Afribary (2021). Accessed November 12, 2024. https://tracking.afribary.com/works/causes-and-control-of-tuber-rots-of-white-yam-dioscorea-rotumdata-poir-varieties-araba-asana-and-puna