Why does the Torah keep on repeating the different kinds of garment on which the Nega appears (See Pesukim 49, 51-53)?
Ramban, Moshav Zekenim: To stress the fact that Tzara'as on garments is a miraculous phenomenon that has no natural explanation. 1
What is Tzara'as Mam'eres"?
Rashi #1: It means a painful Tzara'as. 1
Rashi #2: It means 'Ten lo Me'erah' ('Curse it' - Do not derive any benefit from it).
Moshav Zekenim, Hadar Zekenimm (46): A Me'erah (curse) was sent into it. In the end, the Nega will spread in all of it, and it will be burned.
The Ramban's text in Targum Onkelos is 'Segira Mechazra' (in place of 'Segira Mechasrsa), and he explains it like Rashi's first explanation (Refer to 13:51:2:1).
Which presumably, means that it detracts from the garment and destroys it. (EC)