Description:
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<jats:title>Abstract</jats:title>
<jats:p>In an attempt to evaluate the occurrence and economic importance of
plant-parasitic nematodes in organic farming in Germany, a survey was
conducted with the main emphasis on vegetable and cereal production systems.
For vegetables, the survey included quantification and identification of
plant-parasitic nematodes in soil samples and a questionnaire for growers
querying production factors and damage levels. For cereals, the survey
focused on quantification and identification of plant-parasitic nematodes in
soil and plant samples. Overall, Pratylenchus and Tylenchorhynchus were the
most prominent nematode genera under both production systems with an
incidence of over 90% of the samples. Meloidogyne was detected in 51% of the
samples in both systems. Other nematode genera showed differences between
the two production systems. In production systems with a high frequency of
vegetables, Paratylenchus was detected in 56% of the samples and Heterodera
in 15%, whereas in rotations with a high cropping frequency of cereals,
incidences of plant-parasitic nematodes were 56% for Heterodera, 47% for
Trichodorus and 45% for Paratylenchus. Yield losses could exceed 50% on
carrots, onions and cereals and were most pronounced on sandy soils. In many
cases, nematode problems started 5 to 10 years after conversion to organic
farming. The survey indicated that plant-parasitic nematodes are widely
spread in organic farming in Germany and can cause severe damage which may
result in complete loss of the crop.</jats:p>
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