How to use variable when looking for a part?

Sorry if my title doesn't make sense. i don't know what what i'm trying to do is called.

i'm making a way to place trees and harvest fruits of them. The trees can be placed by the player. When they place it my first script places the tree and names it to tree(number). For every tree placed the number increases by one, so they all have unique names.

My second script lets the player click E when near the tree to harvest it. It does this by checking the list of trees and when its found a tree within 10 studs of the player makes the fruit drop for them to pick up. Here is the code for making the fruit drop.

local treenumber = 0   --treenumber is the amount of trees checked
TreeValue = game.ReplicatedStorage.TreeValue.Value

wait(1)
local Player = game.Players.LocalPlayer.Character:WaitForChild("HumanoidRootPart")
local UserInputService = game:GetService("UserInputService")



UserInputService.InputBegan:Connect(function(keyCode)
        if keyCode.KeyCode == Enum.KeyCode.E then     --when e is pressed

            print ("E detected")        --verify e was clicked
            local treecount = TreeValue.Value   --treecount is the amount of trees in the game

            while treenumber < treecount do      --while the number of trees is bigger than the amount of trees checked

                    print ("checking trees")   --verify checking trees
                    local treename = ("tree".. treenumber)  --set the treename to the current tree name being checked
                    print (treename)          --verify
                    wait(3)
                    local tree = game.Workspace.Base.ItemHolder.treename    --set tree variable value to a certain tree
                    treenumber = treenumber + 1         --add one to the amount of trees checked and check the next tree on next loop

                    if (tree.Position - Player.Position).magnitude < 10 then  --if player is close to tree                       
                        wait(0.1)
                        print ("shake from tree"..treenumber)  --verify that shake has been detected

            end


        end

            end
end)

Here is the error it gives me: "treename is not a valid member of Model" on line 22. The code is searching for the name of the variable (treename), not the value of it(tree1). How do i fix this?

Sorry if my code or explanation is hard to read.