Q. Can you cut branches from fruit trees, for Shavuos decorations?

Many Poskim permit cutting branches from a fruit tree for use in the Suka or for Shavuos decorations since they maintain that the prohibition of felling a tree applies only to the complete arbor. (Mishne Lemelech – Isurei Mizbeach 7: 3, Har Zvi O.H. 2: 101, see also Yechave Daas 5: 46 and Be’er Moshe 5: 133).
Others maintain that cutting branches is also prohibited. (Bais Yitzchok Y.D. 142, Shmiras Haguf Vehanefesh 250: 8, Mekadesh Yisroel 67 et.al.)

Horav Shlomo Miller’s Shlit”a opinion is that we clearly see from the Shmita prohibitions that you are allowed to prune fruit trees. Therefore, if it is not detrimental to the tree, you can cut some branches (not in Shmita).

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a.