Basic HTML Version
P A G E 1 1
V O L . 3 , N O . 3
D E C E M B E R 2 0 1 4
As discussed in the November ’13 SAVA Conser-
vation newsletter, we have been promoting the
cultivation of large yams (
Dioscorea
sp.) in the SA-
VA region as an alternative to tavy (slash and burn)
rice and manioc. Manioc or cassava (
Manihot es-
culenta)
is heavily consumed in Madagascar during
periods of rice shortage and is the staple food of
many African countries. However, much recent
research has pointed to numerous health prob-
lems associated with heavy manioc consumption
such as goiter (very swollen neck from thyroid
gland enlargement), cretinism (severe physical and
cognitive stunting), and konzo (irreversible leg pa-
ralysis). It is now clear that manioc roots and
leaves contain a cyanogenic glucoside called
linamarin, which is a substance that converts to
cyanide (one of the most infamous poisons) when eaten. If manioc is properly processed before eating by exten-
sive drying, soaking, rinsing, and baking, far less cyanide is produced (Nhassico et al., 2008; Nzwalo and Cliff, 2011).
The yams are known locally as “ovybe”, meaning big potato in Malagasy. Some of these yams can actually weigh
more than 40lbs though most weigh about 20lbs. Like manioc, they can grow well even in very poor soil, but are
much less susceptible to cyclone damage than manioc which is a tall shrub. In collaboration with CARE Internation-
al, another training on yam, sweet potato, and taro planting was carried out in November 2014 in Antanimbaribe
(about 15km north-west of Andapa). It was well attended by more than two dozen participants over several days.
We also recently harvested our own model yam plantation in Ambodivohitra, just above the model fish pond,
where we had planted nearly 100 yams about 9 months ago. We harvested 75 leaving 25 to grow for another 9
month cycle as an experiment to see how large they may get or if they would rot and die. The 75 harvested yams
weighed an average of 22lbs each (see photo)! We were able to see all in two days in Andapa for a total of 50,000
AR or about $20 USD. Clearly there is real demand for yams locally although they are not extremely valuable as a
cash crop they can be an important food source and may be sold as well.
More trainings and plantings of yams are planned for villages proximate to Marojejy National Park, in the near
future.
References
Nhassico, D., Muquingue, H., Cliff, J., Cumbana, A., and Bradbury, J.H. (2008). Review: Rising African cassava pro-
duction, diseases due to high cyanide intake, and control measures.
Journal of the Science of Food and Agriculture
,
88: 2043 – 2049.
Nzwalo, H. and Cliff, J. (2011). Konzo: From poverty, cassava, and cyanogen intake, to toxico-nutritional neurologi-
cal disease.
PLoS Neglected Tropical Diseases
5(6): e1051.
First Yam Harvest and More Trainings!
by Dr. Erik Patel and Charlie Welch
Left to right: William (Ambodivohitra fish pond guardian), Desiré Rabary
(holding a newly harvested yam), Soazaka, and Charles Razafindrafara
(yam farmers from Antalaha).