P&PDL Picture of the Week for
August 30, 2004

The Importance of Pruning Young Trees

Mike Dana, Extension Landscape Horticulture Specialist, Purdue University

A late July thunderstorm provided a reminder of the importance of pruning young trees to prevent or remove narrow branch crotches.  Branch angles of less than about 30°, resulting in branches that nearly parallel one another, eventually appear to "grow together."  Of course, they actually grow adjacent to each other, but fail to form any structural connection which would afford structural strength.  When a typical severe summer thunderstorm strikes, with winds in the 30 - 50 m.p.h. range, trees with such poor branch structure are prone to breakage.  Figure 1 and 2 are a 'Bradford' callery pear (Pyrus calleryana 'Bradford'), while Figures 3 and 4 are sweetgum (Liquidamber styraciflua). 

Click image to enlarge

Figure 1

Figure 2

Figure 3

Figure 4

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service