HELP Branches breaking off

Branches are breaking off at the main stalk. THe branches are weak and break easily with little weight. There is a grey mildew or fungi at the site of the break. Can any one help this problem please.

how old is she she looks years old lol

She is only 4 months old. Took her as a clone and her sister right next her is doing fine.

ties her to some strong thick poles support the branches all around make sure its not slackin and slumpin downwards