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
Jesse says
Hi Chrystyna – you can treat with spinosad year-round in hot weather, just do it in the evening when its hot out. And you can cut the plants back around January/early Feb.
Dean says
I have this white fuzz/ mites on my Ruella plants. I see about using the All Seasons Horticulture spay oil, but I have an unopened bottle of Neem oil…can I use that instead. It’s early April, so I dont know if I should treat and cut plants to the ground at this point.
Jesse Jenkins says
If they look pretty bad then yes, cut them down, fertilize with Medina Growin Green, and spray with Neem OIL once they begin to resprout.
Deanna says
I am having bad luck with my favorite plant. I planted and they looked beautiful until those white patches took over. Sprayed with a recommendation from a nursery and did nothing. Removed them since they were not looking good at all. Planted new ones in another location and it’s happening again. Bought the oil and not working. They hardly flower and look bad. Should I cut them down? Or remove them. Very upset I can’t grow these.
Wyatt says
Hi Deanna – I’m sorry to hear you are having such a hard time with your ruellia. We would still recommend cutting them back, as soon as the plants start to flush spray every two weeks with an oil for 2-4 weeks. You may also try contacting the Nueces county extension office (361-767-5223) to see if they might have any other solutions.