ALTERATIONS OF AGROECOSYSTEMS IN GREECE THROUGH PESTICIDE USE. THE 'PHALARIS CASE'

摘要

Plant populations respond to pesticides by various ways. Response is by far more rigid in agroecosystems because of monoculture, lack of genetic diversity and selectivity pressure. The case is more apparent in weed communities because herbicides are planned to have a direct effect on weeds sparing the crop in the degree their selectivity mechanism allows it. From the biological point of view, response of weeds to repeated use of herbicides is resistance, which leads to its ecological consequence, namely a shift in the weed flora. This phenomenon, if not timely diagnosed, results in overdosing and consequently in ecological burden. A drastic weed species shift caused by herbicides in lettuce crops of Greece has been reported in 1988.