The short video explains that the sticky substance on your leaves is honeydew, a sugary substance excreted by aphids, psyllids and a few other plant pests. Ants harvest this substance to feed their colony and guard these pests from beneficial predators and parasites that can help lower pest populations.
The video demonstrates how easy it is to use a sticky barrier to prevent ants from accessing your trees and shrubs to reach their food source. Sticky barriers are a useful type of physical control, that, when used with other integrated pest management methods, can help keep plants pest free.
For information on ant management, visit the Ants resources page at http://ipm.ucanr.edu/ants
UC IPM has over 35 other helpful home and garden videos, visit http://ipm.ucanr.edu/IPMPROJECT/videolibrary-ur.html to watch more.