I recently bought this Brazilian rain tree from a nursery in Florida. I live in Dallas Texas (Zone 8b). Lifting the tree out of the pot to examine the roots, I noticed these fuzzy yellow balls. Can someone tell me what they are? Nematodes?
Did you watch the stream on Identification of Root Aphids? Health Identification: Root Aphids | Bonsai Mirai Live Buy a decent loop or magnifier and use good light to answer your question.
Is the tree relatively healthy? Looks like a heavy organic soil. Way too much large organic material.
Looks more like fungal mycelium or bacterial growth; because of the soil type. Repot and move on…
It looks like yellow peat mold (Chromelosporium fulvum). Comon in greenhouses. Changing the soil may help, but it can grow on vermiculite and other sterile media. Not sure if it will affect Brazilian raintree aversely, but trifloxystrobin (Flint: https://www.solutionsstores.com/flint-fungicide) is the recommended fungicide if you want to play it safe.