I never took any large fan leaves off. But yes, it does look like a nitrogen deficiency. Although I have used the same plant food for many years. My one other thought was. I mix my own potting soil, same as for many years. Adding in worm castings for nitrogen, but my supplier changed brands, so I now sell a product that doesn't even look like worm castings, but supposedly with a mix of nutrients. I dont have a bag to look at the list. I now have gone to another supplier to buy worm castings. I do have young plants that so far look healthy with this mix I am using. Although the test I did two days ago showed a neutral reading, if not slightly alkaline.