This disclosure relates to agricultural canopies used primarily to control the amount of light and/or moisture and/or heat reaching growing plants within the canopy footprint. More specifically, it relates to mechanisms for pulling a flexible canopy over a support structure and then for removing the canopy to uncover the structure and the plants below. The mechanisms include an arm mounted rotationally on a base. When the arm is rotated in one direction the canopy is pulled over the support structure and when the arm is rotated in the other direction the canopy is pulled off the support structure.