You need to use 1 x 100 dynamite to remove the middle-size pond in front of the tree. Dynamite can be won in a Roulette (daily/Birthday special and other), it is also a reward for clearing Diamondland and gifted from time to time, you can also buy it for emeralds.
https://gyazo.com/1a4ddef9f561fb7db33bc229a97cab15