Yellowing leaves?

[Goodroot]

My 20 yr old Mikawa Yatsubusa has several leaves turning yellow and falling off. It has been very healthy. It’s usually the last tree I have to turn red in Dec and then lose leaves. This is Sept 1!
Its been under a shade cloth last 2 yrs. Intense sun here in NE Tx. Seems to like it. I have t sprayed anything to make it “sick”. We have had miraculous rains this summer. Usually bone dry and HOT. Only had 2 days of 100.
I’m concerned at what’s going on. Never did this.

 

[Shibui]

Early leaf colour change is usually an indication of stress where I live. For me, that's usually too dry so I'd check soil moisture and consider recent watering patterns. Need to remember that every year the tree is in a pot fills the spaces in the soil with roots. Eventually there's no spaces left for water so it becomes more difficult to maintain hydration wit 'normal' watering.

Overwatering can cause similar symptoms as roots begin to rot and the tree cannot absorb water even though the soil may be wet.

Nutrient deficiency can also cause yellow leaves and premature leaf drop but that's much less likely and I cannot see any of the usual nutrient deficiency colour patterns.

 

[Goodroot]

I saw a video from Peter Chan saying he only repots every 5 yrs or so. I like him a lot, but I don’t agree with that or his psycho pruning ways. Too fast. I haven’t repotted in 3 yrs here. Usually every other yr. I suspect that’s my problem. I will repot in Spring.
Let me ask this: here in NE Tx zone 8b, I always transplant in the Fall so the roots get established for our long hot summers. Could I do this work in the Fall or absolutely wait till Spring? Why the difference? Thanks.

 

[rockm]

I saw a video from Peter Chan saying he only repots every 5 yrs or so. I like him a lot, but I don’t agree with that or his psycho pruning ways. Too fast. I haven’t repotted in 3 yrs here. Usually every other yr. I suspect that’s my problem. I will repot in Spring.
Let me ask this: here in NE Tx zone 8b, I always transplant in the Fall so the roots get established for our long hot summers. Could I do this work in the Fall or absolutely wait till Spring? Why the difference? Thanks.

Spring is the absolute best time to repot. Fall not so much. People will tell you it’s a great alternative but it is not

 

[Shibui]

I don't have much experience with fall repotting. Spring works well so I have not seen the need to try any other options so I can't offer a valid comparison. I do know I can chop maple roots really hard in late Winter and early Spring. Not sure if I could do the same in an Autumn repot.
We also get long, hot Summers and my maples do not have any problem after Spring transplant. In my experience, new roots grow rapidly in Spring. I'll be potting tridents and JM next week (first week of Spring here) Tridents will have roots showing at the drain holes by start of November and Japanese maples a few weeks later, well before it gets really hot. That's 2 months from roots cut to stubs to pots full of roots.

 

[rockm]

I saw a video from Peter Chan saying he only repots every 5 yrs or so. I like him a lot, but I don’t agree with that or his psycho pruning ways. Too fast. I haven’t repotted in 3 yrs here. Usually every other yr. I suspect that’s my problem. I will repot in Spring.
Let me ask this: here in NE Tx zone 8b, I always transplant in the Fall so the roots get established for our long hot summers. Could I do this work in the Fall or absolutely wait till Spring? Why the difference? Thanks.

Repotting every other year is a little too often IMO. Over time it can weaken trees. I managed to kill nice Korean hornbeam following the ever other year repotting strategy

Repotting should be when the roots start clogging drainage. That can take three or four years depending on the species and age of the tree. I repot my old trees every seven or eight years. Gettting a little root bound slows top growth and helps with ramification.

 

[Goodroot]

Thanks for the clarification.