The past couple weeks, several customers have brought in pieces of Ruellia (Mexican Petunia) with worrisome white splotches on the leaves. At first glance, it could appear to be a fungal issue or even a chemical or paint residue, but that’s not it… Here’s what to look for and our recommendation for treatment.
The white funk is actually a type of growth distortion called erineum caused by tiny mites called eriophyid mites (Acalitus ruelliae). So that means fungicides would be a waste of time and money to solve this issue. We recommend treating organically with All-Seasons Oil Spray (a horticultural oil). Repeat the treatment every 5 to 7 days for a total of 3 treatments, wait until Spring, then cut the plants down to ground level. This should kill the mites and the plants should grow back out and look beautiful again. Another approach would be to use organic Spinosad soap or Bee Safe 3-in-1 Spray to treat the mites, then cut to ground level in Spring and wait for clean regrowth.
-DeAnna
Tami says
What causes them ?to wet, to dry ,not enough sun ,shade ? Because we have a lot of different junk on our bushes and it just seems like if a plant is going to get sick it will happen in our yard!!! I have never had such a problem with these fungus and or mites. We live on the nature coast of Florida
Kerry says
I live in Naples, FL. I planted Ruella about 6 months a & love them .. They’re now tall and have been blooming for several months .. Suddenly they’re covered in that white powder “stuff” and I can see some of the leaves are distorted.. Should I cut them down now ( September ) and if so, how far down ?? I’ve tried a spray from a local nursery without any success .. Thanks for any suggestions ..