I have a few jasminum sambac plants in containers at home, all planted in Al's Gritty Mix and watered regularly with a weak Foliage Pro solution.

The plants have seemed relatively healthy and started putting out new growth now that spring has arrived - but suddenly one has taken a nose dive. Brown and yellow patches have appeared on the leaves, and affected leaves dry and fall off shortly thereafter.

It looks like it might be a nutrient toxicity or deficiency, but it seems odd that only one jasmine plant is showing these signs when my care routine is identical for all 3.

Anyone know what this might be?