Samenvatting

Potato, came from south America long time ago, the tuber is grow about everywhere in the world to become the fourth worldwide crop. Its worst enemy is an oomycete, the Phytophtora infestans. This disease is responsible for millions of deaths and forced migration in Ireland during the Great Famine from 1845 to 1852. The Late blight is present everywhere the potato is present. Its development conditions are easy to find : only liquid water and temperature between 18 and 26 °C. The disease (Late blight) is able to destroy a field in less than two weeks. To fight this pest, a lot of chemicals are present on the market with several molecules. Are also present, the biocontrol solutions such as the Potassium phosphite. Those products are based on natural process to inhibit the disease and/or improve the natural defences of the plant. The objective of this reseach was to come up with a recommendation about some chemicals tested. This thesis is based on a trial, the main question was about determinate the best chemicals during the active growth period of the potato.