Help! What are These White Splotches on My Ruellia?

gillnurseryProblem Solving52 Comments

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. 


52 Comments on “Help! What are These White Splotches on My Ruellia?”

  1. Our mesquite tree leaves are covered with something that looks like this. Is it the same mite?

      1. It also helps to have the area cleared of debris, get good air flow and remove the excess mulch and dead old growth from the base of the plant. I agree its powdery mildew. Getting to wet, plant is a jumbled mess with no active pruning causing a jumble of growth to trap moisture and produce the unsightly mildew.

  2. I live in Houston and I have been trying to find out what to do about the white splotches for months. After the freeze in February 2021, I figured that would take care of it, but no it didn’t. Recently I showed leaves to Randy Lemmon, our Houston Garden guy. At first he said it looked like I spilled paint on them, then he saw a little red mite and said to use Spinosad. Even with spraying with Captain Jack’s Deadbug which contains spinosad, the mites never seem to go away. Maybe I need to try the horticultural oil now.

    1. Yes I would try the oil spray now that temperatures are cooling down. Then cut the plants back in the Spring

  3. These are on my hibiscus and i just replanted some larger ones next to the regrowth of smaller will the large ones also get contaminated?

    1. You probably have mealybugs which is a different bug. Spray with Spinosad soap once a week for 2-3 weeks, If you have a heavy buildup on the stems, you may want to do a light cut back of the tips and then spray.

    2. Yeah sounds like pink hibiscus mealybugs. Prolly a bit late to this reply. Getting lady bugs to get released and prevent the chemical treatment from eradicating the healthy insect is one way to treat. The other would be prune off the effected growth and bag it immediately. I find I can get control over it with bi weekly treatments of Bifen, and Imidacloprid along with some triple 20 to force green color and blooms.

  4. Will thee mites affect all our plants? What can we do as a preventative measure to protect them?

        1. The mites don’t need to be treated, if its caused by mites. They are just forcing the curling of the leaf, to create a habitat that is suitable for them. It wont be affecting all the growth. They don’t harm the plant, and it will encourage other beneficial insects into your garden to allow you have an organic self contained garden without the need for insecticides. Encourage your gardens to be self sustaining. Don’t hunt down solutions to a boon you would be squandering.

        2. You can get a jewelers eye piece, and check the growth on your plant yourself. You tell us, what it is please?!

    1. Hi Sally – yes it is too hot to use horticultural oil this time of year. If you choose to use Spinosad or Bee Safe, make sure the plants are well hydrated, and spray in the evening when its cooler.

      1. 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.

  5. I live in the Florida Keys and my Ruellia does not get cut down for the winter so how to deal with these mites? Is there anything I can spray that would be ok for our year-round hot weather? Should I cut it back even if there is no winter here? And, if so, when? I do cut it back every so often, otherwise they grow too tall and leggy.

  6. 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.

    1. 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.

      1. 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.

  7. 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.

    1. 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.

    1. Hi Amy – none of these are harmful to hummingbirds. Spinosad is harmful to bees, but Bee Safe is not. Horticultural oil should not be harmful to bees as long as you apply in the early morning or in the evening, and do not apply while bees are actively foraging in the area.

  8. I have this on my plant also. First year of planting it in a pot. So beautiful but not so much now. I’m in Nebraska so I will just cut it back since cool weather is coming.
    Next year hopefully I can stay on top of this issue. I’m assuming I will have to dump the dirt & start fresh, not sure if these mites live in dirt during winter months?
    It was such a beautiful plant this year.

    1. Hi Diane – we do not think the mites will live in the soil over winter. We recommend a few treatments with horticultural oil before you cut the plant back. Hopefully that will take care of the mites and you’ll have nice new growth when it comes back.

    1. 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.

    1. 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.

  9. 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

  10. 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.

  11. 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.

    1. 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 🥺

  12. 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

    1. 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.

    1. 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.

  13. 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?

  14. 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.

  15. I live in Florida and have the same issue with my Ruellia. Should I use neem oil or spinosad in the evening? Thank you 🙏

    1. Hi Chrissy – we recommend treating with All-Seasons Oil Spray (a horticultural oil), ideally in the winter months. Repeat the treatment every 5 to 7 days for a total of 3 treatments, then wait until Spring and cut the plants down to ground level and they should grow back nicely.

  16. Having the same problem in Jacksonville Florida, my Ruellia is normally healthy and flowering, just bought some new one from nursey and they also had the white on leaves. One plant is usually full of flowers but they are sparse now. We need some kind of solution for these pests. Its so hot here now and nights are warm as well what should we do now

  17. What causes them ?to wet, to dry ,not enough sun ,shade ? Because we have a lot of different junk on our bushes and it just seems like if a plant is going to get sick it will happen in our yard!!! I have never had such a problem with these fungus and or mites. We live on the nature coast of Florida

  18. I live in Naples, FL. I planted Ruella about 6 months a & love them .. They’re now tall and have been blooming for several months .. Suddenly they’re covered in that white powder “stuff” and I can see some of the leaves are distorted.. Should I cut them down now ( September ) and if so, how far down ?? I’ve tried a spray from a local nursery without any success .. Thanks for any suggestions ..

  19. I am seeing this as well in Houston TX area. About half of mine have white fuzz and nearly stopped blooming.

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