U

Union (Crotch) – The junction between stem and branch or between stems. 

V

Vactor Truck – A truck equipped with a large tank and vacuum unit able to remove loose soil or soil-water slurry. Used with water or air pressure to remove soil around tree roots. This equipment is used to remove soil or soil slurry when excavating around tree roots. VTA (visual tree assessment)- Method of evaluating structural defects and stability in trees.

Vertical Core Venting – A procedure that creates vertical holes, usually about 2-inches in diameter, that extend down through compacted soil. The holes can be from 18-inches to over 3-feet deep. Holes are spaced from 6-inches to 2-feet depending upon the site soil conditions. Holes are created with an auger, water jet or using an air spade. 

Vigor – Overall health; the capacity to grow and resist physiological stress.