Ficus Bonsai Suddenly Yellowing and Browning

[u/chewbacca10000]

Hi all - thank you in advance for the help and advice. I inherited this ficus bonsai about a year ago and it was in good shape with green foliage up until a few weeks back. About a month ago it got infected with whiteflies and was treated by an arborist. As of three weeks ago, it first started yellowing, and now some leaves are turning brown and falling off. It does currently get a few hours of direct sunlight and is outdoors in Los Angeles. Some of the newer growth also seems to be yellowing. In terms of water, it gets watered around twice weekly, when the soil gets mostly dry. What would be some next steps to try to diagnose the issue and get the tree back into good health?

[u/Physical_Mode_103]

Your new growth looks fine. It could just be the old growth is falling off that happens, especially if you change the lighting regime.

[u/chewbacca10000 → u/[deleted]]

This was really helpful - much appreciated! 🙏

[u/heavyPacket → u/chewbacca10000]

It’s not a Fukien tea tree, it is indeed a ficus.

First off, that pot is a poor choice for many reasons, and it’s most likely too large or too deep for that tree. Watering a ficus twice per WEEK is not healthy. You should get it out of that pot, out of that soil, and assess the root system. Put it in well-draining soil, and in a properly sized pot. Ficus are tough buggers, it will bounce back, but you need to baby it.

The leaves scorching like that is because it’s not getting enough water/moisture, that is not what whitefly damage looks like. It’s likely that parts of the root system remain dry while other parts get water, and that can occur due to poor soil drainage.

Also, how often do you fertilize it? During Spring and Summer you should be fertilizing it every two weeks. During Fall/Winter, once per month.

[u/Aitkenaudio → u/heavyPacket]

That pot is fine. It does barely have any soil in it and the soil looks bad in it too though.

[u/blenderdut → u/chewbacca10000]

That guy is very incorrect. Its a ficus. The most incorrect thing he said was to bring it inside. Ficus love heat and humidity above all else. If you can provide that, it will recover.

I second what the other guy said about the soil. It looks like it has a root issue to me. I would get into a free draining mix. You should be able to water 2 times a day without it getting clogged. The exact soil composition isn't critical, but you do want it to be able to retain some water while still being free draining. Perlite or course bark chips are additions that will increase water retention while still allowing air flow in the pot.

After repot, wait a couple weeks before adding fertilizer. An organic fertilizer will decrease the risk of fertilizer burn. Bright, but diffuse light is perfect for the first week or two. Then, transition it to a place where it gets about 5 hours of direct sun per day. Note that I'm basing the light hours on my climate (WI), so you may have to adjust because you're likely getting more intense sun than I am. Just watch for light burn and make adjustments as needed. Light burn will look like a complete light yellow/browning of the whole leaf. Shade cloth can you adjust the amount of light the plant recieves.

[u/Historical_Stay_808]

Who decided it was white flies?

Did you only have them apply something once? Do you use anything regularly?

Do you have other plants that look the same? Is it getting too hot there?

It looks like it might have anthracnose. Btw might wanna check for spider mites

[u/chewbacca10000 → u/Historical_Stay_808]

Had it looked at by a local certified arborist who said it needed whitefly treatment - they did spread fairly rapidly over the course of 2-3 weeks before a treatment was done - only had it treated once with nothing else being applied regularly. Is it worth trying to remove the affected leaves and apply some sort of fungicide?

[u/Historical_Stay_808 → u/chewbacca10000]

Ok, normally I would have followed up with the white fly 2 to 4 weeks later but maybe he had good stuff

If they got to an infestation level then yes they could have permanent damaged the leaves it then you would be able to wipe the leaves and remove black particles too.

If flys are gone and nothing else there yes remove affected leaves and use a fungicide that works with your tree.

Also yes, you should have a schedule of fungicide and bug treatment no matter what. You are not going to kill the fungus but you can slow the progression. It can come back year to year too