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Sunflower Disease Spreads in East Africa
 There
is an ever-growing demand for sunflowers (Helianthus annuus) in the world market
mainly because of its oil, which is considered premium. Subsequently, the
acreage of sunflowers has increased briskly within a relatively short time of 10
years. It is estimated that there are now 15 million hectares worldwide; with
about 590,000 in Africa. But this expansion has not come without problems.
A viral disease has been reported on sunflower and it has been observed in Kenya
and Tanzania. There are also reports of its occurrence in Zambia, Malawi and
Uganda. This inadequately studied virus causes distortion (crinkle) of the
leaves, irregular yellow vein banding, chlorotic blotches and reduced leaf size.
The affected plants normally become stunted. In cases of severe infection, the
heads can be reduced by up to 70%. No vector has been identified that transmits
the putative virus though it can easily be mechanically transmitted from plant
to plant using abrasives. A possible seed transmission has not been demonstrated
so far. The virus is tentatively placed in the genus Umbravirus awaiting
confirmation.
In a study, jointly conducted by the Plant Protection Division, Mwanza,
Tanzania, and the University of Zambia's Department of Crop Science, the
sunflower crinkle disease was found mainly on improved sunflower hybrids with
60% disease incidence in Zambia and 35% in Tanzania. The sunflower crinkle
disease and other such diseases, for example sunflower yellow blotch, are
striking and spreading but are frequently ignored. Consequently, they might
assume epidemic proportion in eastern and central Africa and devastate the
growing sunflower industry. A thorough research is urgently needed to
investigate the etiology and ecology of the viruses to generate information on
what to base on and how to formulate effective control measures.
For further information:
Joseph Ndunguru
Plant Protection Division
P. O. Box 1484
Mwanza, Tanzania
E-mail: ndunguru@brighton.zzn.com
Article courtesy of Agriforum:
Quarterly newsletter of ASARECA the
Association for Strengthening Agricultural Research in Eastern and Central
Africa.
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