Back in june 2017, I presented my work on detecting thistles using CNNs. Here is a recap of what I presented. The paper is somehow stuck in the publishing procedure, so while I am waiting for the result, the conference proceeding is all that is available for now: http://www.efita2017.org/wp-content/uploads/2017/09/EFITA_WCCA_2017_proceedings.pdf#page=187