Yellowing leaves on tree and shrub

Question: Hello,

I have 2 plants I’m curious about. 

1. My Kousa dogwood, very established and healthy, has had some yellowing in the leaves with deep green veining. Also, I’ve seen a number of leaves yellow and fall off. I’m surprised at the number of dead leaves on the ground for this time of year. Could it have been affected by the month or so in May/June with no rain?  Should I supplementally water in those times? Could the underplantings be a problem? Those gardens were added in the last 2 years.  

2. One of my leucothoe doghobble shrubs is showing yellowing with deep green veins. Otherwise still healthy and putting in new growth to match its mates. 3 are planted together. 

Photos:
1: Kousa with yellowing, dying, and also green veining

2. Close up of leucothoe

3. Photo of all 3 leucothoe

Thank you for your help!

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 21, 2023, 1:01 PM EDT
response: Hi,  The Kousa Dogwood looks like it has some chlorosis symptoms which can be typical this time of year with the heat. Those appear to be the old leaves though and look like the new growth is healthy. You can monitor for water as much of Maryland is still in drought like conditions. If the dogwood doesn't show much of a rebound later this fall, you may want to do a soil sample and see how the pH and soil nutrients are. Or you could pro-actively do that now. It looks like there is turf around there and if you have limed it often or recently, that could be part of the cause as Dogwoods prefer more acidic soil generally.  The Leucothoe has some chlorotic symptoms as well, but over all appears to be really healthy! Sometimes those plants can be a little finicky but yours looks good! With it being close to the foundation, you may want to test the soil there as well to make sure it is acidic enough for the plants desirable conditions. If the discolored foliage is bothersome, you can prune it out of the plant as the leaves won't 'repair' themselves.  Let us know if you have further questions or if you choose to do the soil analysis, we can help you read and interpret the results.  Emily

responder: The Question Asker Replied July 25, 2023, 2:06 PM EDT
response: Dear Emily, Thank you for this helpful response!  I was wondering if it was chlorosis.  If I do a soil sample and find the nutrients are low.  What are the healthy nutrients to add for chlorosis?  Something like Iron Tone?  Also, I've heard good things about SuperThrive.I'm curious, is this something that could threaten the Kousa's life in just one year, or since it is so established do you think it will rebound next year?  I will do some infrequent deep waterings of the Kousa for the rest of the summer.  The leaves with chlorosis continue to yellow, die, and fall off.  The Leucothoe still looks happy and hasn't deteriorated any further.Gratefully,JessicaOn Fri, Jul 21, 2023 at 1:01 PM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 26, 2023, 1:55 PM EDT
response: Hi Jessica,  Overall the health of the Dogwood looks pretty good. The soil analysis will tell you what could be lacking (not typical for Iron since our soils are usually pretty well balanced) but more likely pH level due to the lawn setting and proximity to the sidewalk we can see.  pH affects nutrient availability for the roots. So before fertilizing, see if it needs adjusting to lower it into a more ideal range for acid-loving plants like dogwood and leucothoe (otherwise, no amount of supplementation will provide much benefit).  A nutrient deficiency alone is unlikely to kill a tree in a short amount of time like this and it should be able to make a recovery. A general-purpose complete fertilizer should be fine, since it will contain micronutrients and there is no need to tailor an application to just iron or another nutrient as they can be hard to find anyway. Research hasn't demonstrated that vitamin- or hormone-based additives like SuperThrive have any benefit beyond the usual fertilizer components, so it should not be necessary to use. Avoid over-watering as this can lead to nutrient deficiency symptoms and leaf shed before more drastic branch dieback occurs; dogwoods are sensitive to overly-wet soils but leucothoe tends to be more adaptable.  So bottom line is get that soil analysis first before adding any fertilizer or nutrients and we can help with the reading if you need clarification.  Emily

responder: The Question Asker Replied July 27, 2023, 12:22 PM EDT
response: Dear Emily, Thank you so much for all of this helpful information!  I will keep this in mind and keep an eye on these plants.  Take care,JessicaOn Wed, Jul 26, 2023 at 1:55 PM Ask Extension <<personal data hidden>> wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 27, 2023, 1:09 PM EDT
response: You're welcome!