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
Connie says
Hi I live in palm springs ca. And noticed my stems ONLY are almost all white, we had a heavy rain a couple weeks ago and they are still blooming but the stems have me worried because I have not found one thing on the internet that describes just the stems turning white,like they have been scraped or painted. They leaves look fine. help please
Jesse Jenkins says
Hi Connie – we haven’t seen this appear only on the stems here in South Texas. You should contact your local or nearby UC agricultural extension office to see if they can advise. Or possibly local garden centers who have encountered the issue.
Mark says
Can I treat in the spring as a preventative? I seem to get them every summer.
Jesse says
Hi Mark – We are not confident that treating preventatively will work. But you can treat now and cut back and the clean new regrowth should carry you through summer.