Improper Light
Yucca canes prefer indirect to bright light. Too little will cause growth to slow and leaves to begin to yellow. Place in an eastern, southern, or western window.
Moisture
Providing proper soil moisture (or lack of moisture) is important in caring for a Yucca Cane. The most common cause of yellowing leaves among Yucca Canes is overwatering–they don’t need much water to survive. Only water when 75-100% dry. Water until water flows freely from the drainage hole at the bottom of the pot. Be sure to discard any excess water that flows into the saucer, as this can lead to root rot and the eventual death of your Yucca.
Pests
Sap-sucking bugs like spider mites can drain your plant of moisture. An infestation quickly manifests itself by yellowing leaflets and fronds. Scale, mealybugs, and spider mites occur frequently in indoor conditions. If not killed early on, these small pests proliferate and move all along leaves and fronds and into nooks and crannies. The piercing mouths of the insects exhaust your plant and accelerate yellowing, especially if your Yucca Cane is already unhealthy from a nutrient deficiency or improper soil moisture.