Maybe you're watering too often, especially if the soil is potting soil and not proper grit. Yellow leaves are a sign of too much water. What is your tree planted in? How much light and humidity does it get? And how often do you water and how do you do it?

Yellow leaves can be an indicator of too much/too little water, a high level of soluble salts in the soil (solution), a root-bound condition, an insect infestation, a nutritional deficiency/toxicity, high root temperatures, natural senescence, and a few other issues.

If the 'sap' droplets are just the slightest bit sticky, it COULD be guttation, but guttation is commonly manifest through leaf tips and margins, which leads me to believe you're probably dealing with an insect infestation - likely scale. Look on branches and possibly leaves for little bumps that come off when you scrape them with a toothpick or nail file. If you find none, look for evidence of mealybug - little white spots that look like mold or minute tufts of cotton.

If you rule out bugs as the issue, start on the list and eliminate the things you know it ISN'T. How long since the last repot? I'm asking about a repot - not a simple potting up.

Al

Mine did this after repotting. I used N.E bonsai soil when i repotted. I noticed that that the tree condition was gradualy becomin poor. So I lifted the tree from the pot rinced out all soil. And then i made a soil mix 1 part bonsai soil/ 2 parts Miracle Grow potting mix. It has been growing Crazy ever since! If your seeing Sap on a rain tree. i would hit it with some Bonide systemic for house plants. That will take care of Any pests that might be a problem. Is your Tree indoor or outdoors?

Anyone know why brazilian raintree leaves are coming out almost white??

Other than 'the leaves of a BRT are white', you provide no information. Image of the entire plant - including the pot, and a close-up of an affected leaf, please? The reasons a plant's leaves might turn white are legion.

Do you fertilize? Iron, magnesium or zinc deficiencies can cause severe chlorosis, as can a nitrogen deficient nitrogen and/or proteins.

pH can do it by making most nutrients unavailable for uptake.

Exposure to sulfur dioxide, ozone, or an oxidase like hydrogen peroxide

Several bacterial pathogens can do it. Example: a bacterial infection of Pseudomonas syringae can causes complete chlorosis on plants in the aster family.

Al

There ya go

That the leaves are turning white is undoubtedly serious, but still a secondary concern to the serious state of decline the tree is in, and being so chary with information is unlikely to prove fruitful.

Part of the process of leaf abscission (shedding) is the reclamation of nutrients which are considered mobile in the plant (nitrogen, phosphorous, potassium, magnesium). Since the magnesium atom is central to the pigment chlorophyll, magnesium is reclaimed at the expense of the chlorophyll molecules. No chlorophyll - no green.

I would review all cultural conditions in an effort to decide which demand the plant's tolerance of conditions it is not genetically programmed to deal with. There, you'll find your answer. If you want to look at an Overview of Good Growing Practices in order to see which of your habits are most divergent from what you read, follow the link.

Finally, don't place too much hope on the air layer as the plant's lack of vitality is almost assuredly an insurmountable impediment.

Al

So you are saying there is nothing I can do to save the tree?

No, I'm not suggesting that. Whether or not the tree can be saved depends on what changes you make and whether or not Mother Nature thinks your efforts are appropriate. The plant is circling the drain and about to lose its grip on viability, which means 'wait and see' is not an appropriate response, being proactive is, which means it will take a measure effort on your part if you feel sufficiently invested in its recovery. I provided a link to an outline that addresses good growing practices, an outline you can use as a baseline to evaluate what you're doing and perhaps get a sense of what is driving the decline.

With nothing in the way of information to go on other than the image and playing the odds, I'd guess over-watering and/or an inappropriate grow medium is the underlying issue.

The plant wants very bright light, temps between 70-80, regular fertilizer applications with an appropriate fertilizer, and a well regulated watering regimen which includes flushing the grow medium regularly.

Al

But all of that is incorrect. I have had this tree for at least 5 years, and have never had issues with it. It has always put up massive growth and been very healthy. The temp of the terrarium is around 72at all times at a minimum, and the grow light it is under is very bright and is on for about 16 hours a day. The grow light emits a little hear which brings up the temp to about 80 around the tree. I check the moisture level daily to see if I need to water it or not. I fertilize with a liquid bonsai fertilizer every 2 weeks. And the soil is in a bonsai mix, which I have used since I first got the pot. I repotted the tree this last summer. So I have no idea what’s going on. I have checked for pests, and none. My best guess is I moved to an new house and it has hard water and I had soft water before. I’m using a britta filter for the water I use to use to water the tree. But honestly I have no idea why this is happening and even after reading the link you provided, I have no idea what to do.

What, in what I said, do you think is incorrect, and do you think it might have been better to supply the information above to begin with?

Do you control/regulate the humidity level in the terrarium? The BRT likes high humidity, but high humidity w/o air movement or humidity too high can be a problem because it sets the stage for fungal pathogens. Humidity too low at those temperatures can significantly increase the plant's rate of respiration, which increases the rate at which energy is used and raises the plant's LCP (light compensation point). When operating at the LCP, the plant would be producing as much food during photosynthesis as it burns during the respiration phase. When any organism is using more energy than it is capable of making, for any reason, it always leads to death of the organism ..... unless the limiting issues are corrected.

The pot is very shallow and the medium looks like it supports a good measure of perched water.

Follow link for more about how water behaves in container media.If the medium supports 3" of perched water and the pot is 3" or less deep. the medium will be 100% saturated after you water (if you water correctly). That would be very hard on roots in terms of their ability to function and resist diseases. Have you checked them to see what they look like at this point in time? Does the top of the soil glisten after you water?

If the medium has been allowed to become too dry, it might be hydrophobic (water repellent), which can lead to dry spots and/or little water actually being absorbed at watering time.

What are you fertilizing with, and at what strength? Every 2 weeks is ok if you're flushing the soil when you water, but too often if you're not, unless you are fertilizing at very low rates.

Did you make the grow medium, and if 'yes' what went into it? Would you please show a picture of a handful of medium spread out on a white sheet of paper? I have more than 200 trees in containers, half of which are in bonsai pots, the other half being in the developmental stages. This is the grow medium I have been using with excellent results for about 40 years:

Al

Im in south florida, my BRT dropped half of its leafs after we were hit with 40 degree weather. A few days later the leafs turned yellow and dropped. Currently the buds are open and have new shoots coming out. I water every day and fertilize weekly (except in January).