On-Farm Risikoanalysen zur Entwicklung von Kontrollmaßnahmen bei Kreuzkraut-Arten

Summary

Poisonous Senecio species occur in grasslands of various countries. Their further
spread into farmland must be prevented, but efficient methods for their control are
often lacking, especially under organic farming. We propose on-farm surveys
designed as case-control studies to assess the risk for the occurrence of such species
and present results of a study on S. aquaticus. Following a case-control design, 72
plots were evaluated for their botanical composition, half the plots contained S.
aquaticus. For all the plots, the soil nutrients and the details of management practice,
such as type and intensity of management and fertiliser application, were recorded
from the farmer. There was a high risk for occurrence of S. aquaticus with low nitrogen
fertilisation, with a decrease of management intensity in the preceding 15 years, high
inclination, and gaps in the sward. For the long-term control of S. aquaticus, we
suggest promoting dense swards and preventing sward damage as much as possible.
This paper demonstrates the great power of case-control studies in on-farm research.
The design allows thorough statistical testing using generalised linear models and
provides reliable results in relatively short time. Various questions can be linked to the
management practice on farms and over a wide range of environmental conditions.
Such data can hardly be obtained from small plot experiments.