I know there are more pressing matters than botrytis for some folks at this moment - rain, flood, freeze, and rotting peonies. But I wonder if anyone is seeing an increase in black spots on their peonies foliage and stems this spring due to wet weather. My area has also seen cloudier and maybe rainier than normal spring and some of my peonies are showing signs of botrytis. It seems like some peonies are more affected by others. So I went out and cut off all the black foliage and stems that I saw today and disposed them in a trash bag. I also sprayed fungicide of those most affected. Sure hope it does not spread because we are going to get 2" of rain in the next 2 days.

Somewhere I have read that spreading sand around plants keeps spores from establishing in soil? Fungicide is probably the way to go!
We are very dry here so do not see that problem often.
I hope it does not spread for you!

I am worrying that we may have problems later on as this spring is extremely wet, my newly planted SD is covered by water. Generally I would say higher temperatures with high humidity will benefit development of fungus, we are not there yet in Toronto.

Is Botrytis fungal or bacterial?

It is fungal:

http://www.missouribotanicalga...

I battle blackspot on my roses and I use Actinovate, a bacterial agent that eats the spores that cause the infection. I wonder if it would work for botrytis; or if there's another bacterial agent optimized for this fungus?

Due to the wet weather some of us are having, please be on the lookout for this botrytis before it spreads. It can go quick if we are not vigilant. I remembered seeing only 2 peonies affected 3 weeks ago. Yesterday, I had to trim foliage and even stems with buds off 8 peonies. I do not like to spray fungicide but I rather do it for a few than all of my peonies. Granted that I probably planted my peonies too close so they are more likely to spread.

Steve, I have not used Actinovate, but if it prevents and kills fungal spores, then it is probably effective on botrytis. Do you use it on your roses?> Is it effective? How often do you spray your roses wth it? You probably get less blackspot where you are since your climate is alot dryer than over here east coast.

Karen, this year I started to spray in February. I do mostly the areas where blackspot has been a problem, and roses that are most affected by the disease. We get a lot of UV light here, so I know I need to spray periodically. I think I've done it three times altogether this year. I'm actually pretty surprised at how well it has been working so far this season.

I began using it last year when I had a BS outbreak that touched a few dozen roses. I'd say it brought things under control fairly quickly, a couple of weeks. I'll know a lot more once I see how the garden makes it through the monsoons in July and August. BTW, I also treat the mulch around the roses because I know BS spores overwinter there. One of the things I love is that I do not need to 'wet every surface' to get control; I just have to get the Actinovate bacteria kinda close to the BS fungus, and they seem to find it. Of course, when I see BS on a leaf, I do my best to hit it with the fungicide.

I have a number of herbaceous peonies; but they are pretty young and I've not yet had serious fungal problems. Also we have really dry sping weather here.

I hope you find something that works. It's heartbreaking to invest a lot of time and money in plants only to lose them to one kind of blight or another.

Karen, I believe Cricket Hill Peonies recommends Activonate for peonies. Look on their website.

Thanks Steve and LG! I am thinking of trying the Actinovate on my roses. I grow about 50 roses and some become basically leafless toward August. The Japanese beetles eat some foliage and blackspot did the rest. At least I now know that I have an organic option with the peonies.

kousa said: I am thinking of trying the Actinovate on my roses. I grow about 50 roses and some become basically leafless toward August. The Japanese beetles eat some foliage and blackspot did the rest. At least I now know that I have an organic option with the peonies.

I had exactly the same experience when I grew roses in the NE. It can be very disheartening. My luck improved as I grew old more garden roses and roses bred by Kordes and Buck. I used milky spore to help control the beetles; took three years to have much affect, but it did tip the scales in favor of the roses, . I wish I'd had biological controls for black spot. I used baking soda and I can't prove that it helped much.

Actinovate will offer some control, but is an extremely expensive solution. You can get fenhexamid repacks super cheap on ebay instead of having to buy a million pounds.

10g is enough to last me several years, and I haven't seen any grey mold since I started rotating it in with my other sprays.

We have really had a rash of botrytis in the garden. I wrote to Harvey and Nate and they suggested a 10% solution of bleach on the crowns, cutting the affected stems off. I treated about 15 plants. We will be especially diligent this fall in cleanup and may even make a pre-emptive strike with the bleach solution in the spring.