In this paper, measurements conducted in outdoor line-of-trees scenarios at 10, 36 and 60 GHz are used to provide a benchmark between various modeling approaches for radiowave propagation in the presence of vegetation. The list of selected models include the some of the well known empirical and semi-empirical models available in the literature, the ITU-R P.833-9 recommendation for attenuation in vegetation, and an hybrid approach which uses simple empirical models to characterize the propagation phenomena in the presence of vegetation, and then uses a ray-tracing algorithm to gather all the interactions between the different trees. The performance of the selected empirical model was then assessed against the outdoor measurements and a comparative analysis is provided at the end of this paper.