What is this white stuff?

[andy2019]

I have a Hibiscus tree and lately I see a cotton like stuff on the leaves. Please see my pics. The first one is my tree and the second one is the white stuff.

They are really fluffy so when I hit the leaves with a stick, the cotton like stuff just flies off the leaves. The leaves seem to be fine, not damaged or anything. So I'm wondering what this white stuff is and how to treat it. If it's some kind of disease, I prefer an organic way to treat it if there's one.

Thanks

 

[Chuck]

I have a Hibiscus tree and lately I see a cotton like stuff on the leaves. Please see my pics. The first one is my tree and the second one is the white stuff.

They are really fluffy so when I hit the leaves with a stick, the cotton like stuff just flies off the leaves. The leaves seem to be fine, not damaged or anything. So I'm wondering what this white stuff is and how to treat it. If it's some kind of disease, I prefer an organic way to treat it if there's one.

Thanks

Powdery mildew. Spray once a week with either Neem Oil or a baking soda spray twice a week. If not taken care of it will eventually severe damage your plant. And don't hit it with a stick. All that does is spread the fungal spores to all of the surrounding plants.

 

[andy2019]

Thanks. Do you have formula for the baking soda spray? for example, 1 cup of baking soda = 1 gallon of water?

also how long should I use the soda baking spray please? 1 month? 2 months?

 

[DirtMechanic]

The water is simply a carrier. A couple tbsp (30mg) per gallon is a good start. This is slightly less than a 1% solution. You need a wetting agent also, so a little soap is useful. Try to use a soap, not a detergent. Something from the shower rather than the sink. The idea is that the soda will be left as a residue as the carrier water dries away, and the soap helps it hold on instead of running off. I would treat it every 2 weeks until the weather breaks. Fungi are temp sensitive. When dry a very fine powder from the application will be detectable. Its sodium bicarbonate so its a salt. Don't go crazy. Potassium bicarbonate would be a better long term solution.

 

[andy2019]

Thanks. Here's the formula and schedule I'll use

• 2 tbsp of baking soda
• 1 tsp of body soap
• 1 gallon of water

I'll spray twice a week every 2 weeks in the evening since my tree is facing east so it's pretty sunny in the morning. I'll spray for a few months until it cools down.

 

[DirtMechanic]

Thanks. Here's the formula and schedule I'll use

• 2 tbsp of baking soda
• 1 tsp of body soap
• 1 gallon of water

I'll spray twice a week every 2 weeks in the evening since my tree is facing east so it's pretty sunny in the morning. I'll spray for a few months until it cools down.

Sounds about right. @Chuck and others can talk about winter dormant oils and other things useful to know about trees. The Neem oil is a good idea too, as it sticks, and is insecticidal as well as fungicidal.

 

[Chuck]

Thanks. Here's the formula and schedule I'll use

• 2 tbsp of baking soda
• 1 tsp of body soap
• 1 gallon of water

I'll spray twice a week every 2 weeks in the evening since my tree is facing east so it's pretty sunny in the morning. I'll spray for a few months until it cools down.

3 tablespoons per gallon of water and spray twice a week until the fungus goes away

 

[andy2019]

@Chuck No need to add soap for it to stick?

 

[Chuck]

@Chuck No need to add soap for it to stick?

Yeah, I forgot. Add a squirt of dishsoap

 

[cpp gardener]

Actually, what you have is giant whitefly. Neem's okay, but plain water does just as much. I have read that for some reason worm castings repel them. Try to enjoy the process of attacking them because they're pretty much there to stay. Even systemic insecticides don't work very well. The only real cure is to remove the plant, plant some other plant(not hibiscus or giant bird of paradise- they love them too), and look at pretty pictures of hibiscus.

Sorry for the bad news, it really looks like a nice plant.

 

[Chuck]

I believe you are correct. The reason I said mildew was that I see no evidence of sooty mold which is a sign of whitefly. However, under magnification, it does appear to be whitefly. If it is whitefly spinosad works very well against them.