Fundamental Aspects of Auxin Foliar Spray Applications to Woody Plant Cuttings

Applying auxin as a foliar spray has several advantages over traditional quick dip methods for rooting cuttings. These include potential worker safety and application efficiency. Foliar auxin sprays are also becoming an integral part of propagation systems using automated machine-assisted sticking robotics. However, not all woody species respond to foliar spray as well as a quick dip application for rooting and there are questions concerning application timing as well as the optimal number of applications. The overall goal of the research is to better understand the fundamental aspects of foliar applied auxin to cuttings. The original 2018-19 HRI-funded research is on-going and addressing auxin movement in cuttings related to spray volume and use of a surfactant. The proposed research for 2019-20 will address additional grower concerns related to spray efficacy and potential causes for poor root induction by foliar application in species that respond to basal quick dip auxin application.