Between Dutch organic growers the late blight problems lead to discussions in which a temporary registration of copper products is also suggested. Some growers do not want any pesticides at all, while others see that biological potatoes from abroad are sold in the super markets in years when Dutch organic potatoes are scarce. Those potatoes come from countries, where copper products are allowed. They speak about competition falsification. In the research program to stimulate organic production the choice is made to also investigate the efficacy of copper and other products that are allowed in surrounding countries in organic farming. In the experiment of 2008 different copper containing products are tested. In 2009 this was repeated with the same products, but also other doses and combinations