Answer to Question 1
Trickle irrigation advantages include low initial cost, ease of installation, control of weeds, and water conservation. Disadvantages include tendency of the microtubes to clog with mineral deposits.
Answer to Question 2
As a branch dies, the trunk wood associated with the dying branch depletes its supply of nutrients. It can become so depleted that few microorganisms grow in it, and this gives a protective function against infection.
When a branch dies or is removed, the branch collar, bark ridge, or shoulder ridge provide protection by growing new tissue over the wound.