Scale Insects on Yucca Cane: Identification and Treatment

A 3-week-old Yucca cane has tiny, round, black dots on leaves (both sides) that scrape off easily. Bottom leaves yellow and wilted; top leaves have brown tips with yellow halos. Owner waters weekly and mists leaves.

Diagnosis

The black dots are scale insects (immature scales are translucent; mature ones develop hard coverings).

Treatment

Spray entire plant until dripping with solution: 5 parts water, 1 part rubbing alcohol, squirt of dish soap. Alcohol penetrates scale covering; soap spreads solution. One thorough treatment usually suffices if coverage is complete.

Underlying Care Issues

• Yuccas need soil dry 1/4 down before watering. Weekly watering + misting likely keeps soil too wet.
• If repotted recently, excess soil retains moisture.
• Yuccas require bright light within 2 feet of an uncovered sunny window. Low light makes overwatering easy.
• Stop misting; Yuccas are from dry regions.

The expert offers a Yucca care article via email.

Expert advice from Will Creed, Interior Landscaper, Horticultural Help, NYC.