This is the second plant this has happened to at my house. It’s a powdery white residue. It started randomly on a echeveria/succulent I had for multiple years and completely killed it. A couple months later I got this begonia and it started on it too. I’ve used a spray to kill it, but it won’t go away and keeps getting worse. I haven’t seen it on any of my other plants, just those two.
It’s powdery mildew. What did you spray on it?
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0 J'aime Make sure your begonia gets very dry and try bottom watering it. That will help avoid moisture getting your beautiful leaves. Also spores from mildew and mold spread very easily so don’t disrupt the plant too much. You will need to be diligent about spraying it every couple of days until you don’t see anymore powder forming. The spray you have does have fungicide in it so it should work. I know this type of begonia prefers a bit of humidity but wait until you’ve resolved the mildew problem before you up the humidity. Arber makes an excellent fungicide(yellow bottle) and Bonide also makes a soil drench called Revitalize that controls fungus and mildew in your soil and boosts the root system and the plants own defenses against said issues.
0 J'aime I had been watering from the bottom and waiting until it was fully dry before doing it again. I sprayed the stuff consistently, then ended up cutting a leaf off that it kept growing on. Once I did that, it started growing on the other one. I think if I get this plant again, I will probably not keep it at my house. My work plants in my office do extremely well. I’m not sure what’s going on at my house that is causing this. It’s only been the two plants I mentioned, and my plants are all together on a stand.
0 J'aime It can be really stubborn and it may be on other surfaces in your home causing reinfection after you think it’s gone. Spores can sit in dust, for example in a windowsill. If a light breeze comes through those spores are airborne and will grow on anything they land on that is moist. I had it on a Hoya for about a year. Some plants are more susceptible than others which is why it keeps happening on this begonia. They are extremely susceptible to powdery mildew. Have you drenched the soil with the biofungicide? That can help. Spraying leaves only without drenching the soil can leave spores behind. I hope you can save it. I love that type of begonia!
0 J'aime I had not drenched the soil! I was afraid it would kill the plant if I put too much on it, so I was only spraying the leaves. I ended up throwing it away because it wasn’t getting better and I didn’t want it to infect my other plans in the house. I’ll go through my house and try to wipe a bunch of the surfaces just in case.
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This can happen in wet conditions and bad air flow. Trim the bad parts back if you can, only water the soil (not the plant) and make sure it has good drainage. You can treat the mildew with a baking soda, dawn, water mix.
1 j'aime I sprayed it and cut off the bad leaf. It came back in full force on another leaf.
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Powdery mildew or similar white fungus. Needs good air circulation, as stated. I recommend removing the paper, baskets and other materials around and under the pot. These can block airflow. Definitely let the soil dry out more. The issue will keep returning if the conditions on the plant/soil and in the surrounding environment support its growth which are excess standing water and poor air flow. Avoid wetting the plant is a good suggestion, as Chrissy commented. Mildew needs moisture to sustain it self.
1 j'aime It did it with my other plant that I’d had for years though. That plant had good drainage, open space by a window, and was watered properly. I have no idea how it started, I’ve never had it happen before. This plant I bought like a month later and put in a different room in a window as a precaution. The box is just what I bought it in. It started like a week or two after I got it.
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What type of plant is that?
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