Garlic oil for rotting houseplant roots

Hi

I bought a Zygo orchid (Houseplant) the other day and its showing some distress with a growth tip yellowing and then pulling out. I don't want to go pulling about the roots so thought to add some garlic oil to the watering. I have got clay pellets in a pot holder which are half covered by water which seems to stop over watering and also provides humidity. I was thinking of adding some garlic oil to to the water to help prevent root rot.

I have heard that some native trees are treated with garlic to prevent some die back diseases.

Any ideas?

Thanks.