Thank you for your question. I'll try to assist you. I note that on 8/17/24 you also wrote us about yellowing in your redbud.  At that time, it was suggested that a soil analysis be conducted.  Was this done?  If so, please send me a copy of the report that you received.  Related to this, how did you determine that "our soil pH is a bit high"?

Also in the response to your question of 8/17/24, websites were suggested regarding iron supplements that could be added to your soil.  In this current question, you mention Ferti-lome.  It is not clear to me if you added Ferti-lome back in 2024, or if you are still uncertain about doing this.  Please provide me some clarification on this point.

I'll look forward to hearing back from you so that I can provide a good answer to your current question.  Thank you for continuing to use our forum.

Thank you for your follow up. I so appreciate your time! Pardon me for not giving more information...

I did do a soil test in fall 2024. See attached results. I did add Ferti-lome Liquid Iron in spring 2025 (watered in around the base, and sprayed some on foliage, per the package instructions). I also aerated the soil by means of a manual core aerator thinking perhaps it would help. For both years (2024 and 2025) in addition to the yellowing leaves mid-summer, I have noticed small pale green transparent insects on the underside of the leaves

Thank you so very much for the soil report.  I strongly suspect that you are dealing with iron chlorosis. The 2024 soil pH of 7.8 is more than ten times higher than what would be best for the redbud.  However, your comment about insects suggests an alternate reality that this may not be a pH or iron issue.  Some insects, such as spider mites and leafhoppers, can cause leaves to have an appearance similar to that shown in your 2024 picture.  I really need to see a picture of these insects.  Then I would know for sure.  In the meantime, I will be shortly sending you some procedures that you can do now with the assumption that you are dealing with iron chlorosis.  

Until then:

1).  Get closeup and personal with your redbud by inspecting it daily.  At the first occurrence of leaf yellowing, take a pic or two of the leaves and send to me.  Similarly, if you see these insects again, take a pic of them and get it to me ASAP.

2). From your 2024 pictures, I could not get a good idea of the size of the redbud.  I know that it is now over 10 years old.  How tall is it?  What is your estimate of its width at its widest?  Do you think it could be transplanted?

I apologize for my long delay in finalizing my answer, but I want to get things right.  If insects are the culprits, it might be a relatively easy fix.  If it is iron chlorosis, the situation will be more challenging.

Thanks for your understanding and for using our forum.

As I previously mentioned, there are two possibilities for the current state of your redbud: insects and iron chlorosis. I am going to make suggestions to cover both possibilities. In shorter words, the 2024 leaf picture suggests insects are responsible whereas the high soil pH suggests iron chlorosis. It is possible that both may be at work! I am attaching a side-by-side comparison of a redbud leaf infected by mites (left) and a redbud leaf experiencing iron chlorosis (right) so that you may better see my point.

My current thoughts/suggestions are:

1). Yellow leaves with green veins are classic symptoms of chlorosis in redbuds. The yellowing is due to a loss of green chlorophyll in the leaf. Typically, the veins retain chlorophyll much better and remain green. For your redbud to synthesize chlorophyll, it absolutely requires iron. In most cases, iron deficiency in the leaves is not due to a deficiency of iron in the soil. Many Minnesota soils contain plenty of total iron. The problem is that at high pH, much of that iron becomes chemically tied up in forms that roots cannot take up.

2). The optimum pH for growing redbuds is between 6.0 and 7.2. A soil pH above 7.5 is generally taken to mean that plants growing in such soil may be at high risk for developing iron chlorosis. This is why I needed to know what you meant by, “Our soil pH is a bit high”. The pH scale is a logarithmic scale, which simply means that small pH changes can have significant consequences. An example: your soil pH of 7.8 is TEN TIMES higher than a soil pH of 6.8. See:

https://www.lsuagcenter.com/portals/communications/news/news_archive/2015/january/headline_news/redbud-tree--ornamental-plant-of-the-week-for-january-19-2015 - :~:text=They are not as susceptible,sunny to partially shady locations.

3). Trying to lower the soil pH from 7.8 down to under 7 in a short period of time is totally unrealistic. I doubt that the Fertilome Liquid Iron treatment in spring 2025 made much of a dent in the soil pH. However, this product is what you should be using. Check the product level and other information on the label. If you see “Fe-EDDHA chelated iron” or just “chelated iron, you’re on the right track. I suspect that the following describes the product you used:

https://www.fertilome.com/ProductFiles/2024/03/12/10635 Chelated Liquid Iron One Gallon PO 665 1123-CL_FINAL label.pdf

4). Once the leaves are out and developed and before you do anything else including a Fertilome treatment (late May, early June 2026), hold a piece of white paper under a branch and tap the leaves. If tiny specks crawl on the paper, this is an indication of mites. Webbing, stippling, and dusty-looking leaf undersides also point toward mites. Leafhoppers are more mobile and jump/fly when disturbed. If mites are present, pH correction alone will not fix the leaf appearance. If you see the presence of mites, please let me know immediately. See:

https://extension.umn.edu/yard-and-garden-insects/spider-mites

5). If no evidence of mites was seen and once foliage is near completion do a Fertilome spray treatment on the plant and under the shrub. This would be similar to what you did in spring 2025.

6). Again, keep an eye on things. At the first signs of leaf discoloration, repeat the test for the presence of mites and send me pictures of the discolored leaves.

That’s enough for now. Please keep me apprised of things. Together we will do our best to save your beautiful tree. Thanks for consulting us.

We checked for mites (white paper test) on 5-26-26, and didn't find any. Here are photos of the leaves we took that day. There doesn't appear to be any yellowing (yet!) but there are small markings on some of the leaves. See photos. (We'll continue to monitor for mites.)

I'll apply Fertilome Chelated Iron this weekend.

We restarted the sulfur treatments to address the pH. The package said you can use 2 lbs. to 5 lbs. under the canopy, watered in, 2x a year (spring and fall). We used 2.5 lbs. (that's the size of the bag) we were worried about applying to much and hurting the tree?  (If it helps, she's 10 years old, and about 12' tall). My husband wondered if we used that smaller amount (2.5 lbs.) if we could apply it more frequently (like monthly) for a more consistent application? 

Lastly, a few of the lower branches are dead. Is it safe to prune now? Or best to wait until the tree is dormant?

Thank you sooo much for all your help! I truly appreciate your time and knowledge.

Thanks for the update.

The recent leaf pictures you sent DO NOT look like leaves exhibiting classic iron chlorosis. In prior communications, I sent you an image of a chlorotic leaf. Such leaves have yellowing between veins, with the veins staying clearly darker green. Your leaves instead show scattered whitish-yellow flecks and short streaky patches.  They show yellow “speckling” rather significant areas of yellow. As I mentioned before, these symptoms point to activities of insects, most notably spider mites, leaf hoppers, or some other type of sap-feeding insect. The fact that you were unable to see any mites on the paper is significant but unfortunately not conclusive. You may have done your testing at a time when mites were just not immediately present. You should continue doing this type of testing at least every other day.

I did not previously mention it, but leaf hoppers are also common pests of redbuds. Prior to doing your mite test, first look for these critters. Do this looking slowly. Be on the lookout for small things that suddenly jump up from the leaves. Approach the leaves slowly and look for tiny wedge-shaped insects. Brush the foliage lightly and watch for quick jumping/flying insects. Check the undersides of leaves. Look for white sticky egg masses on twigs and stems See:

https://extension.umd.edu/resource/leafhoppers-home-gardens/

Despite its name, the leafhopper described at this site also attacks redbuds:

https://content.ces.ncsu.edu/potato-leafhopper-in-ornamental-plants

For environmental reasons, I am very hesitant to suggest any insecticide application now. The time for doing this is after we can make a positive identification of an insect.

As I read over my previous communications with you, I fear that I might have mistakenly implied that Ferti-lome Liquid Iron would lower the soil pH. That was a mistake on my part. My sincere apologies. You are on the right track in applying sulfur. If your 2024 soil pH was 7.8, you should be aiming for a target pH of 7.2 to 7.4.

But I'm now slightly concerned about your applying sulfur 2x a year in the amounts you suggested.  Please take a picture of the sulfur product, including its labels, that  you are using and send to me ASAP.  I would like to check things out.  Along these same lines, I'm guessing that you applied this product in a circular area that extended about 9 feet away from the redbud trunk in all directions.  Is this correct?

Many thanks

Thank you for your quick response! 

I'm attaching photos of the sulfur product we used. We applied it under the whole canopy (from the trunk to about 10 feet out) per the package instructions. 

We are still not seeing any mites. However, I did look at the leafhopper links you sent, and THAT'S IT!!! We see tiny wedge-shaped, transparent green insects later in summer. They swarm like a cloud (!) under the leaves. I've never noticed the adults (cyan/red striped)—the ones I've noticed in prior years look like nymphs all summer? Haha. I do not see any eggs yet, but we'll keep our eyes out.

Last summer I applied neem oil (July 2026). I also hung sticky traps. And I did an insecticidal soap: 5 T. Dr. Bronner's liquid peppermint soap + 1 gallon water (August 2026). 

Here's how the leaves look today. Some speckling. A few holes. 

Later in summer (when we see the swarms of tiny insects) the leaves are yellow between veins, the veins remain green. But the yellow is blotchy. 

(I'm sorry, I should have responded to the original question from 2024. I just found that reference number. Putting it here so everything is in one place. #0151859) I very much appreciate all your help!!! 

Thanks for your recent responses.  It looks like we may be getting to the bottom of things.

Tying up two loose ends:

1).  Using 2.5 pounds of the sulfur product, twice a year, is adding a larger amount of sulfur than what is normally prescribed.  This is why initial concern arose on my part.  However following the instructions on the product label, as you did, is good gardening practice.

2).  With respect to your husband’s question, you could do the sulfur treatments in smaller amounts but more frequently.

However, now that leafhoppers are in play, I see no reason to continue with any further applications of either the sulfur or the Ferti-lome Liquid Iron.  There just doesn’t seem to be any need.  The current soil pH of 7.8 should be fine for your redbud.

 With respect to leafhoppers, the two most common species found on redbuds in Minnesota are Erythroneura aclys and Erythroneura bistrata.  Here are some pictures of them so you know what you are looking for.   There is considerable color variation among leafhoppers so if what is visiting you does not exactly match either of these two images, no problem. 

https://www.bugguide.net/node/view/2472066

https://www.bugguide.net/node/view/838135

The likely consequence of doing nothing at this point is that your redbud will continue to have pale stippling or mottling on some leaves, with possible early leaf drop, if leafhopper numbers become high.  I don’t know how old your redbud is, but I suspect it might be close to ten years or so.  For an established redbud such as this, not treating leafhoppers is unlikely to endanger the tree.  Not trying to eliminate this pest would lead to some cosmetic distractions on the tree (discolored leaves).  Leafhoppers may lead to the presence of a sweet substance called “honey dew” on the tree, which in turn will attract ants.  I don’t think that I’ve asked you if ants had ever been seen.

Going forward, here are my suggestions:

1).  Keep things neat and tidy around the base of the redbud.  Leafhoppers overwinter in leaf and plant debris found on the ground.  This coming fall, do a thorough job of cleaning up under the tree.  Don’t compost what you pick up; toss it into the trash.

2).  Do not apply any pesticide, especially those that are broad-spectrum or systemic, at this point (early June 2026).  Keep withholding using pesticides until and unless you see large numbers of active leafhoppers accompanied by an increasing number of affected leaves.  The current leaves having spotting will not regain color.  Use your recollection of what the tree looked like in 2025.  If in 2026 things seem to be worse, then further action should be considered.

3).  If it appears that things are not improving, a contact product such as insecticidal soap or a summer-rate horticultural oil labeled for leafhoppers on ornamental trees would be a lower-impact first option.  It appears that you did this to some extent in 2025.  It may be prudent to begin this treatment earlier this year than what you did last year.  Multiple treatments may be necessary.  See:

https://extension.umd.edu/resource/leafhoppers-home-gardens/

https://hgic.clemson.edu/factsheet/insecticidal-soaps-for-garden-pest-control/

4).  As I earlier said, forego for the time being any attempts to deal with soil pH or lack of iron.  If towards the latter part of this summer, leaves present themselves with the classic symptoms of iron chlorosis let us know, and we could consider what steps should be taken to deal with the situation.

Good luck.  Thanks again for your great patience in our attempts to resolve the issue.

Leaves from 06-12-26. 

Some yellowing between veins. Some big chomps (!) out of leaves. A few insects. No webbing, no swarms yet.

Leaves from 06-17-26.

We're starting to see a lot of insects now. It's been rainy. Maybe the moisture prompted a hatch!

We're thinking it might be Erythroneura aclys (link from you):
https://www.bugguide.net/node/view/2472066

Thanks for the update.

In one sense, it is satisfying to see these critters as they indicate we were on the right track in attributing the chlorosis to insects and not to an iron deficiency. After your mentioning that you observed flying insects in 2025, I felt that leafhoppers were responsible for the condition of your redbud. Your suggestion that your latest pictures are showing leafhoppers is possible, but instead I believe they are showing (I think) adult insects called thrips. I don’t know the exact species. They, too, can cause yellow stippling on redbud leaves. It is possible that we may be facing dual infestations by thrips and leafhoppers. Your redbud is the gift that keeps on giving! With thrips as with leafhoppers, the damage is largely cosmetic and remedial procedures are the same. I am attaching an AI generated image comparing leafhoppers and thrips. Take special note of the different appearances of leaf yellowing attributable to each. Here is some information about thrips:

https://extension.umd.edu/resource/thrips-home-gardens/

https://pesticidecert.cfans.umn.edu/sites/pesticidecert.cfans.umn.edu/files/2022-04/2.2022_Krischik_Thrips_Management.pdf

https://ipm.ucanr.edu/home-and-landscape/thrips/ - gsc.tab=0

Bottom line: whether it’s leafhoppers or thrips or both, the remedial steps are the same so the actual culprit is rather moot. Going forward, I suggest the following steps that are like what I’ve previously proposed:

1). Do not yet apply any systemic pesticides.

2). Direct a firm spray from a hose onto the leaves, especially their undersides. Special attention should be paid to any leaves showing stippling, yellow flecking, silvering, or distortion. You will be attempting to dislodge the critters. Do this daily for the next ten days or so. Spray in the morning so foliage dries during the day.

3). Additionally, now start applying an insecticidal soap or a summer horticultural oil labeled for use against leafhoppers/thrips on ornamental trees. Essentially this will be repeating what you did in 2025. Be sure to follow the application instructions on the product label.

4). Keep monitoring the redbud. Progress and success will be measured by a reduction in observable insects and/or no acceleration in leaf yellowing.

Good luck. Will await further progress reports. Gardening is always an adventure. As always, thanks for using our forum.

Here is the image of which I was speaking.  For some reason it did not get sent earlier.

Greetings.  It has been over three weeks since my last communication.  I would be interested in how your redbud is currently doing.  Many thanks.

Hello! Thank you for reaching out.

The leaves are yellowing a bit more. The recent heat probably doesn't help!  ;-)

After your last message, I started using a hose to direct a firm spray of water onto the underside of the leaves daily to dislodge the insects. It was satisfying to see them flee!

This week, I started applying insecticidal soap (Dr. Bronner's castile soap and water, I read somewhere that peppermint is a bonus as insects don't like the scent?) It seems like their numbers are waning a bit?

Thanks for sending the thrips info. Our insects are thin like thrips, the larger ones seem to have a diamond shape on their back. We were wondering if they're Erythroneura aclys leafhoppers?

https://www.bugguide.net/node/view/2472066

I also started noticing circular holes out of the edges of leaves (see photos). Leafcutter bees? Yikes, should I discontinue the insecticidal soap?

You have the most fascinating job—super sleuth of nature! I appreciate you!

Thanks for your latest information.

Your beloved redbud is most fortunate to have you as a diligent caregiver!

1). For now, I would not be too concerned about the yellowing on the leaves. As you mentioned, this may just be a stress reaction to our current high temperatures.

2). Maintain the hose spraying, especially directing the water towards the undersides of the leaves. This is where the thrips and/or leafhoppers may be sequestered.

3). Keep up with the Castile soap and water applications. Hopefully your impression of waning insect populations is correct.

4). The most common leafhopper on redbuds in Minnesota is Erythroneura aclys. It bears some resemblance to thrips. I am attaching a comparison between the two. As I’ve previously mentioned whether both or just one critter is present is a moot point. The remedial procedures you are following will be effective against either of them.

4). As you correctly surmised, the circular holes along the leaf margins are probably the work of leafcutter bees, most likely a species belonging to the genus Megachile. See:

https://apps.extension.umn.edu/garden/diagnose/insect/garden/flies/medium/leafcutterbee.html

https://www.minnesotaseasons.com/Insects/leaf-cutter_mortar_resin_bees_Megachile.html

5). If leafcutter bees are around, your concern is well justified that they may be negatively impacted by your use of insecticidal soap. However, this would only be true if you sprayed directly on them. Once the soap dries, there is little danger of affecting insect pollinators. Consider adhering to the following guidelines:

a). Spray only if active thrips/leafhoppers are still present and damage is increasing;

b). Spray only in the early morning when insect pollinators are less active;

c). Aim only at affected leaves, especially undersides;

d). Avoid spraying under windy conditions.

Keep up the great work. Your efforts will be rewarded. As for my having a fascinating job, keep in mind I am just a volunteer doing a labour of love, both literally and figuratively.

Yep—it's totally thrips! The photos you sent are an exact match to what we're seeing. I'll continue monitoring the tree, and using insecticidal soap on the lil critters when I see them. Thank you for your continued support!

Glad to have been of assistance.  Good luck.  Keep up with your vigilance!  Your redbud will be eternally grateful!

Hello! I've slowed using the insecticidal soap, there seem to be less thrips, but the leaves are really yellowing now. I think (hope?) it's the dry summer we've been having. We've been watering, but a couple of branches really appear to be drying up. Photos attached. Can thrips/insects kill branches? Should we prune those during winter? Hopefully they'll leaf out again in spring. Fingers quadruple crossed!

Good afternoon and thanks for your recent question. I apologize for being tardy in responding.

Good news about seeing fewer thrips. I think the leaf damage you’ve recently observed is something called leaf scorch. It is entirely environmentally related. The leaves on your beautiful redbud are constantly losing water into the air through a process called transpiration. This is very normal. When the air temperature is into the 90’s, the loss of water via this process can be extremely high. Although you showed due diligence in watering, the rate at which the roots took up this water was less than the rate at which water was lost through the leaves. The leaves then turned brown and dropped. See:

http://extension.cropsciences.illinois.edu/turf/diseases/leaf_scorch_woody/

https://extension.sdstate.edu/leaf-scorch-and-sunscald-garden

I understand your concern that the branches having these brown leaves may be dead. However, I really doubt that this is happening. You can check on this yourself! Do the “scratch test”. With your fingernail or a dull knife, gently scrape a small piece of bark off what you think is a dead branch. Look at color of the exposed tissue. If it is greenish-yellow, the branch is alive. I expect that this is what you will see. If the tissue is tannish-brown, the branch is dead. Do this little test on various branches in various spots. See:

https://www.youtube.com/shorts/gQYy2875GmM

In anticipation of the impending fall and winter, a few comments:

1). Do NOT apply any fertilizer. Your beautiful tree will soon begin a “winding down” process. Fertilizer would only stimulate a rush of foliage development at the expense of strengthening the root system.

2). Keep it well-watered up until the ground freezes.

3). Other than removal of obviously dead branches, hold off on any pruning.

It will be interesting to see how things look in spring 2027 after new leaves appear. To some extent, this will be a measure of how successful your battle against thrips was in 2026.

Take good care of it. Thanks for again using our forum. Keep us informed.