Black/yellow areas on phal leaves, spreading...
 

This is a trader joe's mini phal I got almost 2 months ago. It came home with a couple small bruises and a yellowing leaf that I assumed was store/packaging damage, and pretty decent roots.

I chopped off the yellow-tipped leaf, put some cinnamon/neem treatment on the bruises, and put the plant in S/H.

One of the black spots (on the left) stopped doing anything and has been minding its own business. The other, however, on the right, is spreading:

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(at the upper left there you can see the edge of the leaf I cut)

Underside of worst leaf:

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Overall, though, the plant seems quite vigorous. This new leaf started growing in my care:

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It has two spikes. Both dropped a few blooms in the first few weeks but have resumed producing happy new buds:

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I did cut off a few of the spikes' extra branches, but since the plant was growing well, I didn't take them off entirely. I might now, though.

So should I chop off that whole leaf with the nasty spot? Is this just minor damage, or maybe a sign of a bigger problem for the whole plant?

The black areas are a localized bacterial infection. Cut it out, dust the cut edge with cinnamon and don't water so much.