Princeton Elm insects/diseases

Question: My Princeton Elm is 3 years old and has been pretty healthy.  But it looks like something is eating it and there are white spots on the leaves. Even more disturbing are what look like eggs being laid on the leaves. I have pulled off what I can and double bagged them - it looks like some of them are starting to hatch! Unfortunately I can’t reach all the leaves. I love this tree - what should I do? Thanks so much!

responder: Alison O'Connor, PhD  Replied June 29, 2023, 4:41 PM EDT
response: Hi Linda,  Thanks for your question. I know the insects look bad, but they probably won't cause overall harm to your tree. We're seeing a lot of sap-sucking insects in abundance this spring (aphids, scale, whiteflies, etc.) because of all the rain and succulent growth. If they do damage the tree, it will be mostly cosmetic.  Since the tree is young, you could try just hosing down leaves that have the insects. You can also let nature take its course and let the beneficials move in (which they will). The third option would be to use insecticides, which can harm beneficials and may be hard to apply since the insects are on the bottom of the leaves.  Rain is great! But it has its downsides too :)

responder: The Question Asker Replied June 29, 2023, 11:02 PM EDT
response: ﻿ Thank you so much Alison- this was really helpful! I was worried about using pesticides as well so , after writing you this morning, I went out and tried to carefully remove the infected leaves. Everything was fine until I tried to get one towards the top. Unfortunately when I tried pulling the branch closer, I broke it.      I feel awful - it was totally irresponsible of me.  I made a clean cut but am now concerned about the bare bark.  Is there anything I can do to make it better?  Cover it or put some sort of salve on it?  (Or a bandaid? )   Seriously , I’m so sorry to be bothering you again, especially since it’s all my fault.    Thanks for your patience and support- L On Jun 29, 2023, at 2:41 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: Alison O'Connor, PhD  Replied June 30, 2023, 4:26 PM EDT
response: Hi Linda,  It's ok! Things happen. I would remove the damaged portion that is split down the trunk. Make a 90 degree cut (horizontal cut) below where the split ends. Then just let the tree naturally let the wound seal. You don't need to put anything on the wound - the sealing paints and such were actual found to inhibit wound closure.  Was this the leader that broke? Can you send a photo of the tree from a further distance?

responder: The Question Asker Replied July 03, 2023, 10:08 AM EDT
response: Sorry - it took me a while to figure out how to take and mark the pictures.    I have circled where the damage is. I’m afraid I did hurt the leader.  Do you still think I should cut it off? If so , how far down? ( That’s the lines in the picture with the question mark.)    Thank you so much for all your help with this .  Take care - L      On Jun 30, 2023, at 2:26 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: Alison O'Connor, PhD  Replied July 03, 2023, 11:23 AM EDT
response: Hi Linda,  So it gets a little complicated. Since the leader was damaged, you'll have to train a new leader, because elms tend to be decurrent, they are more rounded, but still will need a leader.  So cut the damaged branch horizontal to the end of the tear...OR remove the branch entirely.   Then you'll need to find a branch that is fairly straight and near the center of the tree. You're going to train that as the leader, so you'll likely stake it to a piece of bamboo with flexible tape (like what you buy for tomatoes). Get it as straight as you can. Then you're going to tip back (prune) the side branches - this will suppress growth and allow the new leader to be the tallest and the longest. You don't have to tip prune much - just a few inches off the ends of the branches.  Essentially you're going to be a nurseryperson for awhile :)  If you don't want to physically train a new leader, I would still pick ONE branch that is near the center of the tree and somewhat straight and tip prune the other branches. The problem if you leave all the branches the same length is that they can eventually become co-dominant and the same size, which leads to issues long-term. The tree will be more susceptible to fail in storms. Side branches need to be about 1/3 the overall size of the main leader/stem.  If you're not comfortable doing this, then call an arborist and ask for assistance. You can find one at http://www.treesaregood.com

responder: The Question Asker Replied July 03, 2023, 11:49 AM EDT
response: Well , shoot. I’m going to talk to my partner who, unfortunately,  was the one who said, “Linda, just leave the tree alone. I’ll take care of it when I get back.”    He may want to try to do it himself but he’s 71 and has a bad habit of thinking he can do more than he really can . ( Which apparently , now that I think about it, so do I.)    But I digress. Bottom line, I’m fairly certain we will call one of the arborists from the site you sent.    Again, thank you so very much for “talking” me through this. Your patience, kindness  and knowledge mean more than you know.   Take care- L   On Jul 3, 2023, at 9:23 AM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: The Question Asker Replied July 03, 2023, 3:40 PM EDT
response: Craig read what you wrote and really feels like he can do this . He ‘s planted all our new ones here, took care of a lot of trees in Georgia and is comfortable with a hand saw.    He has a couple of questions/ clarifications.  1. When he makes the cut , did you say he should NOT seal it ( with wax, etc)?  2.  In addition to the cuts he needs to make to establish a new leader, should he also prune some of the lower branches? ( Please see the pic- just FYI, the injured part is the red dot.)    Again, thank you for everything-L      On Jul 3, 2023, at 9:23 AM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: Alison O'Connor, PhD  Replied July 03, 2023, 4:01 PM EDT
response: Hi Linda,  1. NO pruning paint, wax, or sealing agent of any kind should be applied to pruning cuts.  2. Do the leader training this year and the tip pruning - the tree is young and you don't want to remove too much photosynthetic material because you want to have the tree continue to put efforts into root establishment.    Structural pruning should start AFTER the tree is established - usually two or three seasons. You don't want to do too much too soon. Take it slow. Right now you're just fixing the damage.   The tip pruning cuts need to be shorter than the new leader - is the leader you've tentatively selected really short? It's hard to tell in the photos. Basically tip pruning is just suppressing side growth to put efforts into the leader growth. But all the side branches should be shorter in height.   Don't remove more than you have to - be conservative.