Explaining academic probation as an undergrad on PhD application, after doing well in masters There is another answer sort of regarding this topic Academic dismissal from PhD program. What next? . but my situation is different.

I am currently completing applications for PhD programs in Economics and Statistics.  I have a Masters degree in Economics from which I just graduated.  

I absolutely love these two fields and want to continue with a career in research.  When I was an undergrad though I had a lot of trouble and was put on academic probation.  It was 3 years ago, and I feel that I have matured a lot since (I did very well in masters program GPA: 3.77), but I do not know how to explain it on my applications.  

Some schools specifically ask for you to do so.  Others do not.  The later are the most challenging since I do not know whether or not to even mention it in other materials (such as the Statement of Purpose).  

I can say that I managed to turn it around for two reasons


I developed an incredible passion for econometrics that kept me motivated to perform.
I learned how to work with others more productively.  I developed specific areas in which I was very strong, like statistical programming, and because I was willing to help others with their work (mostly students but a few faculty too), I would receive help from them as well in areas I was weak.


It is a shame that I have this on my record, because I feel I would make a great fit for some of these programs, and believe I have a lot to offer.  Any advice on how to approach this issue would be appreciated.  Thank you
I think you know the answer to this: it's what you just told us. If I read that on an application, I'd nod and keep going, my concerns fully assuaged. (I've read similar, and still recommended admission of the applicants in question.)

If, however, I saw a bunch of lousy grades and a probation notation on an undergraduate transcript with no explanation of what happened and what's different now, that would be a huge red flag for me even considering the better graduate-school record. I would wonder whether the applicant would crash and burn again, and what else the applicant might be hiding from us.

Face it head-on, the way you just did here. I can't guarantee it'll be fine, but I think it's by far the best of your available alternatives. People aren't perfect and they grow over time; we know that, and a lot of us are not averse to second chances. If you learned from what went wrong and put it behind you, that's what we need to know.