Lawn, being a lawn is likely to need fertilization. Whether tree needs it later or not depends on individual situation and not sweeping generalization. Cherry trees do not come back well from heading cuts, tend to grow off at right angles when lopped. Also there is the problem of their disease susceptibility, introducing pathogens through pruning. The tree has a genetic blueprint to even out the top as it grows, does not need to be cut on for this to happen. The way for it to fill in nicely is to have it grow vigorously, not be dwarfed and deformed by arbitrary top pruning and subsequent small, badly angled replacement sprouts. The fact that the one branch grew like a weed on a prior occasion is not made up for by the other branches growing more slowly now. Quite the opposite, in fact. once this guy is up and growing-think Ken's "tree years"-it will behave pretty much just like all the others of its type Yes, definitely - trees have a growth phase and then a reproductive phase during their lives. This is why so many trees have crown shapes that are more upright and pointed for a time and then more rounded and spreading later. Seedlings (specimens grown from seed rather than grafts or cuttings of already sexually mature examples) of wild species trees often do not flower at all for perhaps decades while the top is developing.

>Prunus x yedoensis (Yoshino) cherries have an ability to get much larger than the 'Kanzan'......almost double the size< Both are large and vigorous Japanese cherries, which tend to produce generally similar individual crown dimensions. For example a 'Kwanzan' in Sultan, WA was 50 ft. high in 1993; another example, in Sumner, WA had an average crown spread of 55 ft. the previous year. P. x yedoensis has been measured 55 ft. high in MD (1990), and with an average crown spread of 65 ft. in Seattle (1993). More recent (~2005) measurements for Seattle (USDA 8) include a 'Kwanzan' 53 ft. high, another with an average crown spread of 57 1/2 ft., and a Yoshino cherry 57 ft. high. The charm of the Yoshino is in its perfect balance: its dark rugged trunk, often burly and besprouted, makes an ideal contrast for the quintessentially delicate pink blossoms. Nor is the tree so fussy and weak as the winter-blooming Higan cherry, or so bloated and gaudy as are 'Kwanzan' and the other Sato-zakura --Arthur Lee Jacobson, Trees of Seattle - Second Edition (2006)

i had a kwanzan flowering cherry i planted it march of last year. it did great last year, but in april of this year we got 10" of rain and our yard has lots of standing water in it. after that the leaves turned brown and fell off and it died. i think is was root rot. have you had excessive amounts of rain lately?

can we see a pic of the whole tree .... how old do you think it is ??? ... i sthis the same tree in your other post.. that is having the leaf issues???? ants are rarely a problem in and of themselves ,..... are you sure they are ants?? .... anyway ... sawdust usually mean there is interior rotting ... an there is NOTHING you can do about it ... filling the hole with anything... will most likely only increase water retention ... and increase rotting ... these are short lived trees ... and if you get 15 or 20 years out of them.. you are beating the odds .. perhaps it is time to be done with it.. and start over with a new young vigorous tree ... ken