Leaf Spots on Begonia

greybird_kekeDecember 3, 2012

Is this the start of mildew on my begonia? I just bought this plant a couple of weeks ago, and it had only a couple of small brown spots on one leaf which I thought was some kind of damage. However, they are spreading! None of my other plants have this. I removed the worst leaves and sprayed the plant with Lysol. I hope I'm treating for the right problem....

Thank you for reporting this comment. Undo

Yes, that is mildew - a common problem for many begonias during the fall/winter months especially if they were outdoors and then moved indoors. Spray with fungicide to reduce/prevent further outbreaks; remove worst leaves; keep warm; etc, etc.

Mallets are some of the worst hit and often can be killed if not treated promptly, rexes and polka dot canes are a close second but usually can survive a full fledged outbreak. On canes do pay attention to the stems as well as the leaves since mildew will often go unnoticed there. Lucerna can be severely attacked on the cane itself for example.

A product called Milstop has pretty good results against mildew but is hard to find other than on-line. It is costly as well but you get a five pound bucket of the stuff for around $70 (shipping included - at least it was last year). A tablespoon per gallon of water goes a long, long way.

    Bookmark   December 4, 2012 at 2:04AM
Thank you for reporting this comment. Undo

Hcmcdole, thanks for your reply...this is that 'Midnight Magic' which you said often gets mildew. None of my other begonias have gotten that so far. I hope it's not fatal! It looks good otherwise, even has 3 big blooms coming up.

    Bookmark   December 4, 2012 at 3:17PM
Thank you for reporting this comment. Undo

That is minor damage and won't do any signifciant damage. You can cut the leaf off if it gets too unsightly. Do keep an eye for spreading spots. When the entire leaf or stem gets white then you know you have serious problems. I lost Lynda Dawn (a very dark leaf Mallet) in late summer/early fall from mildew. I could not believe how fast it went downhill to ultimate death. I could understand if it did it in very cool weather but it was still very warm in September.

    Bookmark   December 4, 2012 at 6:52PM
Thank you for reporting this comment. Undo
gregsytch(z9b Tampa Bay)

hcmcdole - you lost 'Lynda Dawn'? Aw that is my hybrid, created it in the 90's. If the weather was warm it is not mildew. Mildew ONLY thrives under cool, moist conditions. More than likely it was just fungus from moisture. I have a pic of 'Lynda Dawn' on my blog at planetbegonia.blogspot.com.
And yes, greybird, it is mildew. Increase air circulation to your growing area to prevent mildew.

    Bookmark   January 11, 2013 at 8:45PM
Thank you for reporting this comment. Undo

How about brown spots on upper leaf surface of "Castaway" with the under surface (which is deep red) of the spots are light green? Thanks.

    Bookmark   May 7, 2014 at 5:11PM
Thank you for reporting this comment. Undo

I stopped mildew on Lucerna's stem using hair spray to coat it. I don't recall whose suggestion it was originally but it did stop the mildew, changed the color of the green stem but that was not important to me.

    Bookmark   May 8, 2014 at 8:44AM
Sign Up to comment
More Discussions
Rhizomatous Madame Queen and Black Truffle
A nursery was discounting their "annuals"....
Anyone have b.grandis bulbils for swap or SASE?
I would very much like to try these if anyone has a...
ID please
I'm assuming this is a begonia, and here in zone 5...
Anyone Know Anything About 'Phoes Chloe' ?
I've had it for at least 8 years - it died back during...
My Special Angel
I posted this in the house plants forum but thought...
Jessie Tyler
© 2015 Houzz Inc. Houzz® The new way to design your home™