The invention provides a hand-held electronic device for injecting an agent into a tree with continuous pressure sensing technology for real-time measurements of the pressure within the tree. The pressure measurement information is conveyed to an onboard central processing unit for data collection, analysis and optimization of the speed of injecting the agent into the tree. By continually monitoring the pressure and injection power, the injection pressure can be modified to adapt to back pressure fluctuations. In one embodiment of the invention the agent is injected into the tree under a preprogrammed pressure profile. In another embodiment of the invention the agent is injected into the tree under a variable pressure profile until the fastest injection time is obtained. The invention also provides methods to identify a problem related to the health of the tree by comparing the measured pressure profile resulting from the injection of an agent into an individual tree with the typical pressure profile, stored in a database, for a tree injected under a comparable set of conditions.
