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Use
of Cultivar Mixtures in Barley in the former German Democratic Republic
The most
remarkable example of large-scale use of cultivar mixtures in
industrialized agriculture occurred during the 1980's in the German
Democratic Republic (former East Germany). Following recognition of the
problems caused by the powdery mildew in monocultures of barley, and of
the high cost of fungicides, the government implemented cultivation of
barley mixtures nationwide. As the acreage of cultivar mixtures increased,
the severity of mildew declined from greater than 50% to less than 10%,
leading to a large reduction in numbers of fields treated with fungicides
(Wolfe 1997). Interestingly,
in Germany, the synthesis of cultivar mixtures for disease resistance was
less than optimal: numerous cultivars were used to produce a range of
mixtures but many of the varieties contained the same resistance genes;
i.e. cultivar diversity was far greater than resistance diversity. Despite
this disadvantage, the mixtures were used until the time of political
re-unification of East and West Germany when governmental support for the
project was stopped (Wolfe 1997). Since 1990, barley monoculture has been
re-established and fungicide use increased. |
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