Hinoki Sekka Health Issue - Darkening and dying leaves

Asking for a friend (I swear!)
She treated and fertilized her hinoki sekka as follows:

Treatments:

Early-mid April - used the Bayer Feed and Protect systemic annual treatment - at 1 tbsp per gallon.
Early April - used the Bonide granulated systemic - used the recommended amount which equates to roughly a light dusting over the container surface - example 1.5 tbsp for a 5 inch pot.
Mid-July - reapplied the Bonide systemic for last treatment for summer.

Fertilizers:

These first two fertilizers below were given on a really hot day about 8 weeks ago - whenever that first real hot spell came that lasted about a week. It was on a 90+ degree day. Other plants reacted to this badly also - with some burned edges - but at first this tree seemed un-phased.

Neptunes’ Harvest fish fert - Full strength 1/8 cup per gallon - applied this both as foliar spray and in soil watering
GS plant food Liquid Kelp - Full strength 2 tbsp per gallon - applied this both as foliar spray and in soil watering
(Below are newer fertilizers I bought to replace the ones above after the seeming bad experience and horrendous odor from both of them.)

Bio-Weed Seaweed fertilizer - may have had a small amount in one or two watering - but it’s like 1/2 teaspoon per gallon at full strength.
Garden Safe Insecticidal Soap (+ Isopropyl alcohol) mix - applied once to Sekka about 3-4 weeks ago. The browning had already started by this point but it has gotten much worse over last week to two weeks.

Bottom line, recently the tree started looking stressed, losing leaves and branches. She thinks the cause is over fertilizing during hot weather. I checked the tree and it’s fairly wet, but no sign of root rot (at least no odor). I recommended she slip pot in pure pumice to help roots dry out a bit, which she did yesterday.
Any other thoughts? Any experience dealing with this for Sekkas?
Here are some photos.

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Is the plant being kept indoors?

Hey Gabe!
Thanks very much for posting this thread and getting the conversation started.
With your intro, I will fess up and own my situation. No need for you to get bogged down with the replies. Very much appreciate the sendoff.

Hi Frank -
No - the Sekka is kept outdoors on a balcony in bright, indirect light - south-facing.

Just brought the tree indoors to get photos where the light did not wash out all the color - so better color rendition of the foliage.

Based on the information presented I would refrain from any further treatment or fertilizer. My approach would be to monitor the watering to ensure that the tree remains moist but the roots do not remain wet. Only water when the top I inch of substrate has started to dry out!
The location sounds good from a light aspect, how about the wind?

Looks the damaged branches are the ones with wire, when was that put on?

There are other branches that are affected that are not wired. Wire was just applied last weekend in an attempt to ensure airflow and light were getting into and through the foliage. I was a little bit concerned there was inner dieback because of lack of penetrating light as a possibility. So wire was very recent and this started about 2.5 weeks ago easily. Good question though!!

Tree gets regular airflow and some gusts - not full wind though. It’s mostly protected - but it is very very hot here in NC at this time of year. So I’d say periodic breeze or gusts but not in a direct constant airflow…

Definitely have been holding on fertilizer and no further treatments were planned. So I am being super conservative now about everything.

The foliage looks a bit like sun scorch or windburn I get on cedar and cypress when they dry out The rest of the foliage looks ok, so my suggestion would be to just focus on the proper watering routine and observe the tree. If the sun is hot and direct at times select a shadier spot while it recovers.
Wishing you the best.

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I have a lot of sekka that look like they’re from this same batch and I noticed a bit of this too. Physical damage was sometimes the culprit, and other times I think it resulted from root loss during repotting (I was aggressive with some of the trees). This tree doesn’t look like it was repotted so I’d recommend that for next year.

Is fungus a big problem for hinoki in NC? Am curious about the fungicide treatments.

Am also curious about the watering. I keep the trees in full sun and the ones that get the most heat have grown the most. I water daily and sprinkle overhead whenever I pass by with a hose.

In general, I don’t recommend applying fertilizer on particularly hot (or sub-freezing) days, but fertilizer can be applied any other time. That said, I’d be surprised if these products caused the damage.

And although some of the damage looks like it could have been caused by the sun, what strikes me is that other branches, including the tender growth tips, look great. Uneven damage suggests the roots aren’t totally happy - not a surprise given the soil.

All of this to say I’d watch the water carefully, letting the tree start to dry out between waterings as Frank suggested. Misting or overhead watering can also help as long as there isn’t a big fungal problem.

Hope this helps!

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Hi Jonas -
Thanks for the reply and insights!!
You’re correct - no repot since I purchased this tree at end of February. No fungicide treatments have been made. The systemics were preventive only because several of my other trees regularly get hit by mites and scale. (I only recently found out that Sekka don’t typically pick up pests as easily - so I was being unknowingly overcautious.)

What I am really wondering about today is ----> This Sekka - along with several other trees had a strong reaction shortly after I made one application of the first two organic products on this list. They were given at full strength both foliar and in water - on mid-90s days (indirect light). The reaction happened on an indoor mame boxwood as well that I had sitting in some late afternoon sun. On the boxwood more of one side of the tree was burned than the other… When Frank mentions “sun” burn - it made me wonder if certain ingredients in fertilizers can cause the foliage to be more sun-sensitive than normal (just like certain products applied topically or ingested by humans can make them more sun-sensitive)?? Or maybe it’s just plain root burn showing up in this way… Not sure at all - some of the plants seemed to love that product mix but a few had a bad reaction. And the indoor did not have any of the systemics, but still had a similar reaction. Coincidence?

Good questions. It sounds like coincidence, but it’s hard to say. Sunburn refers to discoloration that results from the patches of foliage directly in the sun. It usually has a splotchy appearance. When single branches show damage but not others I suspect physical damage or a root issue.

I’ve used organic fertilizers at several multiples over the recommend dosage and have yet to see signs of trouble as a result. The most common signs of fertilizer burn are brown margins for deciduous bonsai, and brown tips on conifers (though this is less common).

Trees are definitely more sensitive to sunburn when they are compromised, but it doesn’t sound like the applications you made could do the trick on their own. If the trees were dry or if anything else was going on, that might make a difference.

The main thing at this point is to watch the watering carefully and hold off on using any fertilizer or pesticides for the time being.

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