Leaves turning yellow then black

A few leaves look deformed and are developing yellow spots that look as they may eventually be turning black. Here are a few pics, please take a stab at guessing what it is. Thanks!

Did you find out what it was?

I'm having the same type of problem.

Tips curl then start turning yellow and black, then turn really brittle and break when touched.

Just over night it took out 3 or 4 leaves.

is this indoor or outdoor.... looks like a slight magnesium deficiency and btw, how old is the plant

what ph are you using to water or feed those plants? mine was a ph issue along with mites. looked just like that, they are in recovery right now.

c5rftw may be right with the mag deficiency, your ph will lock out certain nutrients if its not in the right range, something else to think about.

I suggest flush with ph adjusted water and see what happens, also look under the leaves and see if there are any tiny eggs or mites cruisin around.

When in doubt.....flush it out.

don't know what it was but i did flush. it occasionally happens to some leaves but it doesn't seem to be affecting much. i am battling PM every week and using a Neem based fungicide so i thought it might be that but everything looks good now except a few more leaves but Im getting more new growth than loosing leaves and everything else is nice and healthy. the strain is Bubba Kush. I just trimmed it up and will post more pics if necessary but I definitely think flushing is important and probably helped.