Why is the money tree losing its leaves? An analysis of five causes

The money tree (Pachira aquatica) is an evergreen tree that prefers a hot and humid climate, has poor cold tolerance, and its seedlings are intolerant of frost; it is relatively tolerant of wet conditions and also slightly tolerant of drought.
Watering
When the money tree is overwatered, the potting soil stays wet for a long time, causing a lack of oxygen in the soil, which rots some of the fibrous roots, hinders normal respiration and the absorption of water and nutrients, and causes the leaves to turn yellow and drop. After being affected, the young leaves first turn pale yellow, and then the old leaves gradually turn yellow as well. Watering should be stopped immediately, fertilizing should be suspended, and the soil should be loosened regularly to keep it well aerated.
Fertilizing
Overfertilizing causes new leaves to be thick and fleshy with many uneven bumps, while old leaves dry at the tips, turn scorched yellow and drop. Fertilizing should be stopped immediately, watering should be increased so the fertilizer drains out through the drainage holes at the bottom of the pot, or the plant should be repotted right away, with the root ball rinsed with water before being replanted in the pot.
High temperature
In summer, if flowers that prefer cool conditions (such as cyclamen, fuchsia and wax begonia) are placed in a hot spot and exposed to direct strong sunlight, the leaf tips and margins of young leaves are very likely to scorch, or the leaves turn yellow and drop. They need to be moved promptly to a well-ventilated, shady spot.
Humidity
The air around the money tree is dry. When indoor air is overly dry, some flowers that enjoy a humid environment, such as spider plants and orchids, often develop dried leaf tips or scorched leaf margins. Measures such as misting and covering with a plastic film tent should be taken to increase air humidity.
Pests and diseases
Leaf spot disease caused by infection with fungi and other pathogens easily leads to localized necrosis of the leaves, with yellow spots or patches appearing; in severe cases the entire leaf turns yellow and drops. After infection with mosaic virus, mottled yellow and green patches appear on the leaves; when attacked by pests such as scale insects and red spider mites, the leaves also turn partially yellow and dry, or even the whole leaf wilts, turns yellow and drops. In all cases, pesticide should be sprayed promptly for control.