Old post but I may have the same issue. looking for advise also
In February I gave this plant/pot a good water then applied about 1/2 cup (2-4 oz) of 10-10-10 granular fertilizer on top of the soil around the outside of the pot away from the trunk and any pups. At the time the pups where really non-existent. (about 1" high and haven't gown in 9 months). Week later the main plans leaves drooped. 2-3 weeks later all of the main plants leaves yellowed and slowed died off over 4-6 weeks. Mother plant stopped growing. 4 weeks after the heavy fertilization the pups took off and grown 3 pups that are 20 24" tall in 10 weeks. Main pant is still suffering. It also had spider mites (or still does)
I separated 1 pup 3 weeks ago
The 2nd pup looked great until now. As you can see in this photo something is impacting the leaves.
I think this is fertilizer burn of some sort.
Thoughts
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Newmarket, Ontario, Canada, Earth