Strategic Planning of Phytosanitary treatments in Wineries

We consider planning phytosanitary treatments in a vineyard. We are given a set of diseases (or requests) that must be treated for each site. Product mixtures are defined by their composition of active components, and their duration of protective power for each request. Machines are available to spread the mixtures on the sites. The time horizon is divided in time periods. Sites are partitioned in sectors. The objective of the problem is to minimize the machine leasing costs, their travel cost to sectors and the costs related to the product use. To solve this problem, we use a column generation approach where the machine policy and the product order policy are pure master decisions, while treatment planning decisions are made in individual pricing subproblems associated with each site. We developed a dedicated dynamic program to solve the pricing subproblems.