What are these black spots on my yucca that are spreading upwards?

The spots are on the upper side of the leaves showing through on the underside and are oval in shape, indented with a clean black line around the edge and initially what appears to be tiny spots in the centre when I look under a magnifying glass. Some of the spots join together. I noticed on one of the leaves on the underside, a small slug and its trail from spot to spot leaving small blobs of sticky liquid. I have removed most of the affected leaves but it has reached about halfway up the plant. The leaves eventually turn yellow. Its a beautiful plant and I don't want to lose it. Thank you.

yates

25 November 2018 05:07 AM

Dear Carol,

It does sound like your Yucca has a fungal spot on the leaves. Too much water and poor drainage can cause this to happen. I know you have had a lot of rain in Queensland over the past couple of months and I think this has contributed to the poor health of your Yucca. If you could improve the drainage, this will certainly help the plant to recover. The fact that slugs are present on this plant is an indicator that the soil is too wet. All you can do at this stage is nurse the plant along. Hopefully the rain will settle down into a normal pattern and allow your Yucca to recover.

Topics: Flowers and Ornamentals Issues: Diseases