Expert: Long Island Gardener - 5/9/2009

Question
I am in Montana, today is very nice, 60's. I took my hanging basket outside for the second time and hung it in the full sun. I watered it as usual. I have been raising this basket since Feb. Today I had my first petunia bloom! 2 hours later I go outside and the petunias look like they're dying! They are all wilted and weak looking. HELP Please!

Answer
Took me a little investigating to come up with this answer, but I don't often learn something new in this category, so thank you for writing to me about your Wilting Petunias.

Initially, because the only time I have heard of Petunias actually wilting like this out of the blue, the cause turned out to be damage.  It could be simply a matter of the crown being bruised and no longer delivering moisture to the leaves.

But it turns out, there is more to this suddenly 'wilting' of Petunias.  The folks at Maryland Cooperative Extension Service have put together a piece on it:

ipmnet.umd.edu/04Jun18G.pdf

Apparently Phytophthora Fungus has been attacking the crowns of these annuals a lot down in Maryland.  'When pulled out, the plants [deceased] look like they have a good root system.  Some Crown Rot can be seen .... Microscopic examination found mycelium and sporangia of the Fungus Phytophthora parasitica...'

To quote from T.S. Schubert's essay for the Florida Dept of Agriculture, Phytophthora Crown Rot of Petunia and Snapdragon: 'Infection generally takes place at the soil line during periods of cool, wet weather... The period just after transplanting is a particularly vulnerable time...'

And a warning, with thanks again to meastro Schubert: 'Chalamydospores very efficiently provide a means of long term survival in soil...'

Translation: Stricken plants must be considered terminally ill, they point out.  Do not re-use the soil in pots they grew in; wash your hands after handling; and soak the pots in bleach to destroy spores.

The good news is these were potted - not in your garden soil.  That means that you don't have to worry about planting susceptible plants, listed on the referenced website, in the same area.

And I AM NOT KIDDING about not reusing the soil.  If you want to do this again, and again, and again, ignore that advice.  I know how hard it is to throw out stuff like this, but it's just one of those things.  Learn my MY mistakes.  Don't reinvent this wheel.  Please!

Excessive Nitrogen fertilizing -- a likely practice at the greenhouse these plants were raised in -- tends to increase susceptibility in many plants.

Sorry to be the bearer of bad news, but it could be worse.  Thank you very much for your question,

THE LONG ISLAND GARDENER