Leaching of propiconazole and chlorothalonil during production of pinus sylvestris seedlings in containers

Abstract

The risk of environmental contamination by pesticides is not well known in container production of forest seedlings. Leaching of propiconazole (Tilt 250 EC®) and chlorothalonil (Bravo 500®) from peat container medium into the ground was monitored during three growing seasons in nursery production of Scots pine (Pinus sylvestris L.) seedlings. Fungicides were applied at about 20 day intervals from the end of July until November. The annual load of leached propiconazole (25–183 g active ingredients ha‐1) was greater than that of chlorothalonil (5 to 82 g active ingredients ha‐1). The proportion of leached to applied propiconazole was large, 4–29%, but less than 1% of the applied chlorothalonil was detected in leachates. The downstream percolation of water in the soil beneath the container area was small. After extra irrigation into the ground, the detected concentrations of chlorothalonil in soil water 0.5 m beneath the ground surface were 0.4–2.4 μg 1‐1.