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
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
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.