If you have a large, invasive tree...the lowest effort way to kill it is to pry the bark off in a complete circle around the base of the trunk to girdle it ASAP. Here's how to do it on Glossy Privet, but the basic technique can be applied on any tree. And a shovel will work too to pry the bark off. The reason why it works is that it prevents the photosynthesized sugars from going down to feed the roots...which then slowly starves the tree. This works on various types of trees. I've tried it myself successfully on Glossy Privet and Chinaberry already. Typically, the existing branches will stop leafing out and it will resprout from below the girdle over the next half year. Obviously, break any of those resprouts off, and keep starving the roots. And then watch the tree continue to die off after that. The great thing about this method is that it requires no toxic herbicides and little manual labor, too. Now once the tree dies for good, you can just let it rot in place for a while before cutting it down in parts at your convenience to prevent falling hazards. Of course, if the tree is a sapling or smaller and can simply be uprooted, then that's even easier and faster. And if it's multi-trunked and srhrubby, then girdling gets a lot harder. But for large, single-trunked trees...IMO, this method is the best option.

Unless the parent tree was own root the sucker yours came from is the sweet cherry rootstock and not the named cultivar that was presumably grafted onto it. Either the rootstock seedling happens to be a yellow cherry as well or the whole parent tree, including the roots was the yellow cultivar. Sweet cherry is actually a weed species in this region and suckers to form groves on local wooded hillsides, where it even overtakes and overtops the native red alder trees often present in quantity on the same sites. It also crosses with the much less exuberant, native bitter cherry to produce a nearly fruitless, intermediate hybrid called Puget cherry. Some ~tall examples of the latter are conspicuous when in bloom, on undeveloped land between I-5 and Lakeside School (near Seattle). It is usual to have problems with suckering and bony surface roots with plantings of sweet cherries - perhaps all the more so when these are present as rootstocks for Japanese flowering cherries. All you can do is uncover the bases of the suckers and saw them away. If there are horizontal runners that lead back to the original planting follow these back to the parent tree and saw them off at their points of origin, pull the rest up. You don't, of course want to saw off normal roots of the parent tree - just the ones that are suckering runners like aspen trees and running species of bamboos produce. This post was edited by bboy on Sat, Mar 15, 14 at 17:05

Just remember Halina it is a big tree they can grow 50-70ft it could have a 45ft tap root. I would not even plant a tree that grew that tall so close to the house I am on 3/4 acre and I dont think this block is big enough for a tree that tall. The Powton is a specially bred and select form of Paulownia kawakami (Paulownia) a native of China. They do not like their feet wet so resent over watering... I know it has a very pretty flower, best to ring up the nursery where you bought it from and ask advice there..Have a look at the link below lots of info there... Cheers..MM. Here is a link that might be useful: Paulownia Trees

not many things die just from cutting back .. as noted by all the prior cut backs on that tree ... cut down.. and apply any stump killer ... undiluted.. per label ... painted on as noted above ... and while you are at it.. i would probably kill the shrub behind ... and replant sone quality plants 3 to 5 feet away rome sent legions to salt carthage .... you dont need that many men.. if you use the right product ... lol ... ken https://duckduckgo.com/?q=stump+killer&t=ffcm&ia=products