Question
I live in the Desert Southwest and have a good sized path of hearts and flowers. Yesterday I noticed some of it was wilting. Today it seems to be spreading fast and patches are dead. It gets full sun and partial shade after 5pm. I water it every other day. I noticed on some of the stem and under the leaves a slight white powdery looking substance. Do you have any ideas about what it is and how to treat it?

Answer
Dear Jim,

It sounds to me as if your plants have a fungus disease - powdery mildew - which needs to be treated with a fungicide.  You should remove the dead plants and any which are very badly affected and then spray the rest of the plants.  

To be certain of buying the right product I should take a sample of the affected plant to the store and simply follow the instructions on the container.  You should spray the plants after the sun has gone over.

I do hope you manage to save your plants.  Why not remove some of the plants which have not been affected, before they are, and then you will have a supply for propagation.

Good Luck

Diana