Hi, and when you ask, about ten days ago, whether or not you should remove or eliminate the stem that did not leaf out, I did respond that you might want to wait to see if the stem in question ends up pushing a new set of leaves, as it might have gotten frost damage on Easter Sunday when we had the snow and cold temperatures, and then again later on that same week.  I have noted many of the leaves on my aspen stems had frost damage (blackened leaves that are "cupping", and have been falling off).  But it is your choice as a homeowner whether or not to remove it.  If you would like a certified arborist to consult with you, you can go to www.treesaregood.org, click on Find an Arborist, click on United States in the dropdown box, then put in your zipcode and ask for certified arborists within a 25-mile radius, for a list of all arborists who have been certified by the International Society of Arboriculture.  As I said, when I responded to the question that you submitted about ten days ago, aspens down here (unless you are living in the foothills or the mountains) struggle.  They are much more adapted to the mountains.  Down here at lower elevations (assuming that you live at a lower elevation) they  have problems with leaf spots, and cankers, along with other things, like aphids, attacking them.  If they are planted too close together for the air to move through the stems and leaves, the aspens can get leaf spots which can return in subsequent years unless the leaves are cleaned up in the fall and disposed of. Here is a portion of my response from ten days ago:   "I also see that your aspen stems have some competition from the surrounding grass. I think they would be much happier if the competing grass was removed from beneath and around the stems, and that area mulched with an organic mulch, such as wood chips. This would help to regulate the moisture in the soil, and even out the soil temperature, as well as create a protection zone for the aspen stems, to protect them from "weed-whackeritis", that is, getting bark damage from a weed-whacker. Remove the grass out to the drip-line, if possible; that is, the line that is even with the outermost twigs of the stem, and replace with an organic mulch. Check the soil in several spots around the clump with a thin-bladed screw driver that you can insert into the soil. If the blade goes in easily, then it's probably getting enough water. If the blade meets resistance and cannot be inserted easily, then the clump probably needs supplemental water. Also, aspens are susceptible to leaf spots and diseases, and if not pruned properly to allow the air to move around and in between the stems, they can, in the summer when we have higher humidity, get various leaf spot diseases that can cause the leaves to get lesions and can even drop prematurely. (See Aspen and Poplar Leaf Spot Fact Sheet link at the top of my response.) If this happens, it is extremely important to do a thorough cleanup and disposal of the leaves (into the trash, not the compost) in the fall, so that the spores of the disease do not remain to re-infect the following year. Or perhaps this particular stem, if it was just pushing leaves when we got the cold weather on Easter Sunday and during the following week, might have gotten frozen leaves, and the stem will have to push out a second set of leaves if it has enough stored energy (carbohydrates) to do that. Good care of the clump would help it with that. I would recommend, if it doesn't bother you too much, to wait and see if it is still able to push another set of leaves yet. Or there might be a wound on the trunk above the seven- foot level that you haven't noticed ? If you can, go ahead and remove the competing grass, create a mulch ring, make sure the clump is getting enough water, and wait to see. If it still doesn't push a set of leaves, then it might be time to carefully remove the stem, making sure not to damage the other stems in the clump. "

We hope to be able to resume our tree team onsite visits around the middle of June, for $25 per hour, and if you would like, you can request that  tree team members come out and look at the stem in person, just to see if there is any canker or wounding.  You can send an email to <personal data hidden> with your request .  However, I would encourage you to take the steps that I have listed above,from  my previous response, to try to renew the vigor of the stem, and wait a little while to see if it will yet push leaves this spring.