Aflatoxin, rosette, and groundnut rust--the climatic environment that promotes their presence and development
1986
Picasso, C.
shThis paper deals with three groundnut diseases in West Africa that are detrimental to yields and quality of this crop. The infection of pods and seeds by a fungus Asperigillus flavus L. that generates aflatoxin, an harmful substance for human and animal consumption, is linked to climatic factors. Field infection is increased by drought at the end of the growing cycle. Rosette is a virus disease transmitted by an aphid. Its development and propagation are directly related to those of the insect, which in turn result from well-defined climatic conditions, notably temperature and humidity. Groundnut rust, a fairly recent but fast-developing disease in West Africa, is also caused by a fungus, Puccinia arachidis S. This fungus has, however, a short viability period for its development in tropical climate. The spread of uredospores, their release, and transport by the wind and the conditions for infection are presented. Till now no intermediary host has been identified, which could explain the permanent existence of infection sources near cropped areas. The present hypothesis is that this disease is transmitted only through the continuous presence of groundnut stalks in the field, by regermination of the crop, or through interseason crops. A good knowledge of the agroclimatic environment that affects these diseases, well defined for certain parameters, facilitates assessment of risks and of the need to take protective measures. It also cuts down the loss caused by these diseases through appropriate cropping methods, so that the parasites do not encounter satisfactory conditons for their development on these plants. This is, however, an interim solution that awaits the use of resistant varieties, the only really effective method of control that could be employed by all far
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