Use of the I-PHY indicator as a decision-making tool in citrus orchards on Réunion – The case of lambda-cyhalothrin

The INDIGO® method’s I-PHY is an indicator used to assess the environmental impacts of pesticides at plot level. Based on an expert system, it takes into account the characteristics of the active substances (AS), the plot and the application conditions. It returns an I-PHYsa score in the form of a mark out of 10. Under these conditions, I-PHY is a robust indicator whose results help to identify practices that pose a risk to the environment. However, the score alone does not, as it stands, make I-PHY a decision-support tool. In this article, we propose using the margins of improvement between the different scores (I-PHY min and max) to construct regression trees that enable the identification of the variables driving the score, thereby allowing I-PHY to be used as a decision-support tool. To illustrate our method, we studied the environmental risks associated with the use of lambda-cyhalothrin among three citrus growers in Réunion. This analysis enabled us to identify the technical measures that these growers could implement.