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
Pamela says
Will these mites infect my other plants around it.
Jesse Jenkins says
Hi Pamela – we’re not sure yet whether these mites will infect other plants. So far we’ve just heard about and seen them on ruellia. But when you treat them and cut back the ruellia, you decrease the chances of them being able to infect other plants.
Debbie says
So finally I have found out what is happening to mine. At first I thought they were mealy bugs but they’re not bugs. It’s like this white stuff all over them. So with it being mid-summer do you recommend just going ahead and cutting them down? I’m feeding the ground?
Jesse Jenkins says
Yes, you could go ahead and treat with Spinosad Soap or Bee Safe, then cut them down and regrow. Don’t use horticultural oil in summer though because it will burn the plants.