Field Evaluation of the Effectiveness of Thermotherapy against Cassava Mosaic Disease in Central African Republic
Innocent Zinga *
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France and Laboratory of Biological and Agricultural Sciences for Development (LBSAD), University of Bangui, BP908 Bangui, Central African Republic and University of Reunion, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Frédéric Chiroleu
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Emmanuel Kamba
Laboratory of Biological and Agricultural Sciences for Development (LBSAD), University of Bangui, BP908 Bangui, Central African Republic.
Charlotte Giraud-Carrier
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Mireille Harimalala
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Ephrem Kosh Komba
Laboratory of Biological and Agricultural Sciences for Development (LBSAD), University of Bangui, BP908 Bangui, Central African Republic.
Simplice Yandia
Laboratory of Biological and Agricultural Sciences for Development (LBSAD), University of Bangui, BP908 Bangui, Central African Republic.
Silla Semballa
Laboratory of Biological and Agricultural Sciences for Development (LBSAD), University of Bangui, BP908 Bangui, Central African Republic.
Bernard Reynaud
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Jacques Dintinger
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Pierre Lefeuvre
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
Jean-Michel Lett
CIRAD, UMR PVBMT, Plant Protection Center, 97410 Saint-Pierre, Reunion Island, France.
*Author to whom correspondence should be addressed.
Abstract
Aim: The effectiveness of thermotherapy in managing cassava mosaic disease (CMD) was studied on a susceptible local cultivar in the field in the epidemiological conditions.
Study Design: The field was laid out in randomized complete block design
Place and Duration: Field experiment was conducted in forest zone at Kapou located in south west of Central African Republic according to University of Bangui during August 2010 and July 2011.
Methodology: Diseased cassava cuttings were treated in a heated water bath at temperatures ranging from 43ºC to 51ºC for 30 min before being grown for 12 months in the field.
Results: Temperatures from 43ºC to 49ºC were found to have no deleterious effect on either the survival of cuttings or on plant regeneration. One month after planting (MAP), up to 40% of the cuttings treated at 47ºC to 49ºC had regenerated a plant with no CMD symptoms compared to 7% of untreated cuttings. Between two and five MAP, cassava cuttings treated at 49ºC produced plants with a significantly lower incidence of CMD than plants produced from untreated cuttings. All plants grown from treated cuttings developed significantly less severe CMD symptoms than untreated cuttings between 8 and 12 months after planting. The highest tuberous root yield was obtained with diseased cuttings treated at 49ºC (4.7kg/plant), equivalent to the yield from untreated symptomless cuttings (4.6kg/plant).
Conclusion: Our data clearly demonstrate the value of thermotherapy to maintain a high level of production using local cultivars under severe CMD epidemic conditions.
Keywords: Manihot esculenta, cassava mosaic disease, sanitation, thermotherapy, incidence, severity and yield, Central African Republic