In many articles that I read about correcting nutrient deficiencies, I noticed that very often foliar feeding is suggested as an option, even for immobile nutrients deficiencies. How does that help the new growth if those nutrients will not move.
If there are nutrient deficiencies, these need to be corrected at soil level and are best prevented from occuring in the first place. Foliar feeding can be useful to apply immobile nutrients (if that is what is lacking) directly to foliage to be absorbed - it's a quick fix for newer growth that has such a nutrient shortage, but steps should be taken to address the problem at soil level too, or the same problem will occur on the next lot of new growth. Both immobile and mobile nutrients are taken up from the soil to keep the plant supplied as it grows.