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
DeAnna says
Ruellia mites only affect Ruellia. You can cut them down, fertilize, and then spray with Neem oil to suffocate the mite. The other pants will be fine.
Kimberly A. Griffith says
Hi, I have many of these Ruellia throughout my garden for 20 years. I live in Florida and every year I cut them back. This is the first year this white powder has shown itself sadly and it has started to spread quickly throughout my garden. I cut them all back in February & March when weather started to warm up. It’s now April 90 degree weather and the white powder is overtaking these flowers. All my other blooming plants are mixed together with my boxwoods, pentas, inpatients, crotons, palms, blue daze, and I am in fear it will spread to them. What is the best way to treat them without harming the other plants & flowers?
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.
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.
Samuel Bolton says
My mistake I thought this nursery was based in Florida for some reason. I would love to see specimens of eriophyoids from Texas on Ruellia to confirm the presence of A. ruellia.
Chelsea says
I’ve got photos of mine, I’m in Texas. Where would you like me to send them
In my case my coleus became infected first and started spreading the love. Im fixin to throw them away, pots and all. Is this an over reaction? I have somewhere close to 50 or so plants and I love them all. I’ve accepted sacrificing these few to save the rest If necessary ????
Samuel Bolton says
Not actually Acalitus ruellia. That mite is not present in Florida. All cases of erinea on Ruellia in Florida are instead attributable to Acalitus simplex.
james says
You should definitely cut your plants back, the last week of January or first week of February. If they are still rather small, 12 inches or less, just prune off 2 to 4 inches, but if they are 2 feet or more, cut them back by at least half, cut as much as down to just 4 inches tall.
benton says
Thank you! im in florida, looks like i have this exact issue. i have the spray ordered and will follow recommendation! since our “winter” is pretty moderate to say the least, would you still recommend cutting to ground in spring? our ruellia have only been planted 2-3 months
Joey Santiago says
Out of curiosity would dish soap and water work as well to kill the mites? Thank you
Jesse says
Hi Joey. We doubt that regular dish soap would be effective. Horticultural oil is effective because it’s heavy and suffocates the mites. Spinosad soap contains Potassium Salts of Fatty Acid (18.8%) and Spinosad (0.1%) which act to kill the mites.
Joey Santiago says
Understood thank you very much.
N says
Will neem oil work on this?
Jesse Jenkins says
Yes – neem oil or Spinosad soap if you want to cut back and treat this Fall. Or wait until January and use All Seasons Horticultural Oil which is heavier and should be used when temps are cooler.