In August Wilson's Fences, the one thing that is not used as a symbol is the cherry tree. We see the other items used significantly in the story.
"Rose" is, of course, the name of Troy's wife. A rose is symbolic of love, and Rose does love Troy. However, his extramarital affair with Alberta (as well as their conception of a child) destroys the marriage. It is worth noting, however, that Rose still stands up for Troy at his funeral when Cory does not want to attend, showing her capacity to be loving regardless of the pain Troy caused her:
Your daddy wanted you to be everything he wasn't...and at the same time he tried to make you into everything he was. I don't know if he was right or wrong...but I do know he meant to do more good than he meant to do harm.
And he will send his angels with a loud trumpet call, and they will gather his elect from the four winds, from one end of the heavens to the other. (NIV)
The turning point, then, and the beginning of deliverance, is when "the great trumpet will be blown."
That's the way that goes.
For Gabriel, the need for the trumpet reflects his desire to open the way for his brother so he can gain entry into heaven, Gabriel's wish for Troy. There is no question for Gabriel as to whether Troy deserves it. Gabriel's love for him is all that is required.
Fences are symbolic in several ways. Literally, they keep things in and/or out of one's property. In the play—symbolically—Rose wants to keep love in; Troy wants to keep Death out. Rose reminds Troy to finish building a fence around the house. Rose's wish for a fence symbolizes a way for Rose to keep her family close to her, as Bono (Troy's friend) explains at the beginning of Act Two:
Some people build fences to keep people out and other people build fences to keep people in. Rose wants to hold on to you all. She loves you.
When Alberta dies, Troy gives Death (personified here) an ultimatum:
Alright...Mr. Death. See now...I'm gonna tell you what I'm gonna do. I'm gonna take and build me a fence around this yard. See? I'm gonna build me a fence around what belongs to me. And then I want you to stay on the other side. See? You stay over there until you're ready for me. Then you come on. Bring your army. Bring your sickle.
All of these items are symbolic to the story: each represents an element of the story the author is sharing with the audience. A cherry tree is not symbolic.