Yellow spots on cacti

[Hero878]

There's some yellow and rust like marks on my new Myrtillocactus geometrizans cv. fukurokuryuzinboku. It seems like this is very common amongst this type of cacti. But any idea how to stop it as I think it may hinder its growth.

Thank you

[Hero878]

Ah sorry I'm so lazy. I just googled it and found out that its rust spots caused by rust fungus. Will spray it with neem oil solution to destroy the fungus causing it.