Are tubers ruined if Dahlias have Powdery Mildew?

9 years ago

I planted tubers for three dahlia types some time ago. This year, I ignored them completely, only to discover that they were covered with white powdery substance. This is at summer's end, which means it stayed like that all summer. I cut down all of the dahlia's leaving only the base of their stems so I can relocate them to dig them up.

I'd like to know, does this powdery mildew affect the tuber itself too? I wanted to relocate the tubers, but I'm worried that if I do, it will relocate/spread the powdery mildew.

Are the tubers supposed to be treated with something? Are they ruined? Please help!

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Comments (6)

CCvacation
9 years ago
It would have been good to treat them with a fungicide while they were growing, but I wouldn't worry about it. Perhaps dunk the tubers in a mild bleach solution before storage to kill the spores on the outside.

One experienced grower hypothesized that powdery mildew compromises the storage quality of the tuber, but that's hit-or-miss, and you can't do much about it if that is the case.

I had extreme problems last year with PM, and sprayed every month for it to keep it in check this year. It only presented itself at the end of the season, when the plants were struggling before dormancy.
User
9 years ago
>>Perhaps dunk the tubers in a mild bleach solution

Could you define this for us? A cup per gallon? An ounce? Do we need to let 'em soak?

Although I've been fighting PM on the plants, it's becoming a losing battle as frost delays yet again. A dunk sounds like a great idea at this point.
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CCvacation
9 years ago
Hmmm... Three glugs? Maybe half a cup per gallon. Mind you, there's no proof this works, but it might help if the PM was really bad and you plan on planting them in a new location.

I plan on dunking all my horizontal fencing in a wheel barrel full of bleach solution before storing them, as PM starting creeping in right before everything was cut down. I won't be doing my tubers, though. Using the same beds, so the spores are all through the soil anyway. Just have to keep the plants happy next season and take preventative action before PM sign.
User
9 years ago
You measure like I do. Three gulgs per gallon, circa half a cup. Thanks!

The PM is minor so I may skip it and just dust with a little elemental sulfur instead.
teddahlia
9 years ago
Cinnamon powder is a good fungicide according to many sources. Chlorine bleach is caustic and can damage tubers if too much is used. Besides cinnamon smells better.
gardengal48 (PNW Z8/9)
9 years ago
It should have no effect on the tubers at all. And since one normally rinses the tubers to clean them and hydrate them before storage, any lingering PM spores will be washed off (PM cannot survive in water).

It certainly won't hurt to dust with cinnamon or sulfur before storage but probably not necessary.

Are tubers ruined if Dahlias have Powdery Mildew?

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CCvacation

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