hi patrick,
i had a plant succumb to mildew/fungus of some sort last spring and i asked a friend of mine for some ideas which i posted to another begonia group. here is a quote of that:
....>
a greenhouse manager friend of mine says you can also
mix in a very minimal amount of non-ionic soap to that
dilution (baking soda and water), or you can run your finger over the top of the dish soap bottle and add that little bit in.

for you chemists, here is a powdery mildew formula:

100ul TWEEN 20 (non ionic soap)
3 grams of potassium bicarbonate or sodium bicarbonate(baking soda)
300ml water

i was also told you can buy some fresh hydrogen
peroxide and mix a dilute spray out of it (with water)
and apply it regularly as a preventative, but i can't
quite remember the ratio.

of course, there's good ol' sulphur.

....

sulphur is a good thing to dust/spray your plants with every so often. it seems like spring/fall are succeptable times of the year for mildews/fungus. the purpose of dish soap, a surfactant, is to power through the protective membrane of many fungi. i hear the cheap stuff is the best.
in addition to using a spray, you might want to consider better lighting (no direct sun, of course). begonias are medium light plants, but many people take this to mean they can tolerate a corner in the back of the house. they would like a bright but filtered light or overhead grow lights if you have them. remember to let soil dry between watering, and if you have doubts about how well draining it is, try mixing in perlite, sand etc.
if worse comes to worse, you can hard prune the canes down to just a few nodes.

hope that helps!

-ming

Don't forget spraying with Lysol. I've heard several people complain about mildew on B. 'Sinbad'. It's one of those cane/shrub hybrids that Californians call mallets (pronounced mal-lay). They all seem to be somewhat prone to it. I've never had a problem with it in my microclimate, but if I did, I would use Lysol.
Elizabeth

Hi Patrick,

I have the same plant and it was beautiful all summer. I bought it this spring in a very large container for a very low price. Curious if it is from the same grower.

It stayed quite lush and full until we got the cool, damp weather. It quickly developed a lot of powdery mildew. I cut almost all my leaves off and am using a Neem solution when I remember (I've sprayed twice in about 4 weeks). I almost had it under control, but after the last 2 days of downpours it may be as bad as ever. The strange thing is I have rooted some broken branches in other pots from the mother plant and they show no sign of mildew.

I also have 'Maurice Amey' and 'Don Miller' which have the same kind of problems. Last winter I did not spray them at all - just kept the nasty leaves cut off and cut back on water drastically. I also had them in a very chilly greenhouse which is usually bad for mildew. When summer came, I moved them outdoors and they came out bigger than ever.

Butch

Thanks folks, for the input.

I'm thinking I'll try the Lysol...if that doesn't work, I'll probably buy a fungicide that contains either Captan or triflorine. I found that recommended while doing a web search.

Ming...not being a chemist, I hesitate to try mixing the baking soda solution........likewise, without the proper ratio on the hydrogen peroxide, I don't want to play guessing games (plus I'm past the "preventative" stage). I'm familiar with sulfur in only the powder form so think I'll pass on that.

Butch...I'll keep Neem in mind...I assume it's a fungicide?
When I got ahold of the plant, there was no grower's tag..only an ID tag. Sorry I can't tell you where it was raised.

Because the Seattle area has a cool, moist climate most of the year, I think a mildew-prone plant like this may best be relegated to indoor culture or put outdoors only during our few short months of summer drought. Mildew seems to set in quickly, with devastating results.

Patrick

Well I'm wrong about B. 'Sinbad' being a cane/shrub hybrid. For some reason I always forget that it's a shrub/thick-stem hybrid. It has characteristics of both shrub and thick-stem, but it is not an angel wing or a mallet cane. It's parents are B. U062, a species from India, and B. dipetala, also from India.

B. 'Maurice Amey' and B. 'Don Miller' share B. U062 as a parent, but the pollen parent is B. 'Torch' (formerly called B. 'Pinafore Sport'). They are both shrubby canes. B. U062 has been used a lot in hybridizing, and the resulting offspring often have mildew problems. Warm weather usually clears it up.

Elizabeth

Warm weather.........what's that?! LOL

Warm weather is something the Pacific NW "might" see for 2 months in the Summer. All the more reason I think 'Sinbad' might best be treated as an indoor plant in this region.

Patrick

You're probably right, but I wasn't really arguing to the contrary. You know your climate conditions and how your plants react to them. Most begonias can be grown indoors if the light is adequate. Of the three begonias mentioned, B. 'Sinbad' gets the largest and will eventually need a large pot. Here's a picture of mine growing happily outside.

{{gwi:440877}}

Elizabeth do you use lysol undiluted?
Frances

Yes, I use the aerosol spray right from the can.

Elizabeth, thanks, I'll try it. Your Sinbad is beautiful.
Frances

Hi Elizabeth,

I wasn't taking exception to your remarks about warm weather; just cracking a joke about Seattle's cool, moist marine climate.

Thanks for sharing the photo...your Sinbad is beautiful. I'm going to go ahead and spray my plant with Lysol, then follow that up with a heavy pruning.

Because our winter light levels are so low, I think I'm going to go ahead and set up my fluorescent light stand to give Sinbad a happier environment. I have other plants that I'll put under the lights as well & have an indoor winter garden.

Patrick

I have the same problem with my Angelwing begonia I believe thi one is a cane plant. I had it outside all summer and then brought it in before it got cold, now there is white powder all over it. I was told to wipe it down with alcohol, it took care of it for a few weeks, but it came back. What do you recommend for curing it?
thanks
David

I have several plants displaying these symptoms and so I recently requested assistance by email from a garden centre. I was told dry air is a contributing factor to disease powdery type of mildew and so I'm very confused now. What everyone here has described sounded like what my plants are suffering from and it seems the contributing factor is the opposite -- dampness.

I'm curious as to how your experiments have turned out. Did your plants survive?

Ianna

Hi Ianna,

Sorry for the delayed reply. My begonia is still leafless, sitting in an unused bedroom where the temp. is around 55-60 degrees. I water it just enough to keep it from drying up and so far, haven't gotten around to setting up my fluorescent light plant stand. When I do, I'll cut the stems back to about 2 leaf nodes each.

I did spray the stems with Safeway's equivalent to Lysol. It immediately dissolved the mildew and I haven't seen any returning. I haven't noticed any negative effects from the spray, so I'm hoping it's a good fix.

The jury is out on whether the begonia will take off and grow once it gets more light and warmth, but I hope so.

Patrick

ok I've been using a mildew spray i got from a local plant store, it seems to work for a couple weeks then the mildew comes back. So i'm thinking about trying the lysol to see if it works. I bought a humidifier to add some moisture to my house. I have the Angelwing in a south window all the time. The leaves are coming back but the are shriveled on the edges. Does anyone have a good input on what i should do next.
Thanks David

Take a deep breath and relax. Wait until the weather is warm enough to move it outdoors. It will flourish then (given the right care). Then the cold will return and anguish will set in again once more.

You could put it under lights for several hours or for 24 hours for that matter if you want growth indoors, but it still won't be as good as outdoors.

The other option is to move to the tropics. As though that is the easiest thing to do.

It'd be my luck I'd move to the tropics and they wouldn't allow me to bring my plants with me!

Ha!

Patrick

Well, things are looking good for 'Sinbad'! I never moved him out of the cool unused guest room, but now that daylight is getting longer and we've actually had sunny days, there are small new leaves appearing at 5 spots so far. I may bring it to the window in my office area where it'll be warmer and get western exposure.

Best of all, after 1 spraying with Safeway's equivalent of Lysol, there has been no more mildew. When the new stems get a little size to them, I think I'll take cuttings.

As for going outdoors later...the jury's out on that point. I may just keep it as a houseplant...we'll see.

Patrick

Patrick, I started growing begonias when I lived a little south of you--Chehalis, if you've ever heard of it--and I didn't know you COULD grow begonias outdoors! They'll do fine indoors if they have enough light, and maybe a little extra humidity. (But it is easier outside, at least in the summer.)
Nancy

Hi Nancy,

Sure I know where Chehalis is...I learned at an early age because I grew up near Chewelah, WA and every once in awhile our mail got routed to Chehalis by mistake! Since then, I've driven north & south past Chehalis on I-5 a few times. And now you're down there in LA (state not city, I assume?!)

I too have grown begonias both indoors and out. But this has been my first experience with mildew issues (except on tuberous begonias in the fall).

Patrick

lol Patrick, I know about the mail going astray, and you might guess things go to Los Angeles instead of Louisiana. Bill used to get mail from the UK sent to L.A. fairly regularly. with Los Angeles spelled out very carefully. Not hard to understand--guess everyone's heard of Los Angeles all around the world!

It seems like a good time to bump & plump, this one up.

A mist of vinegar and water, seems helpful, too. Use about 1/3 to 1/4 white vinegar with water, in a spray bottle.
Watered down coffee, helped, once [I only tried it once].
I use thinned green tea a lot,if things begin to look funny. That idea, came from the seed starting forum.
The variety of things that work, is just fascinating.