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
Chris says
I am seeing this as well in Houston TX area. About half of mine have white fuzz and nearly stopped blooming.
Kim says
In FL and the heat is unbearable, so we never thought mites. Ty for the info we’ll try the oil treatment. These plants are less than 6 months old. 🌷🌴
PCBTom says
I am also in FL, the panhandle, and I had this last year on all of mine. I cut it all down in Oct and let it go. Most places are ok this season. There have been a few plants starting to show a little white. I have cut those at ground level. Some have grown in ok …so far! As hardy as this plant is I have tried in the past to eliminate it in a few areas with “R-U” weed killer but it comes back! Tough stuff to kill once established! I will say that in those areas it grows back without the white!