Below is a copy of the information found in one of our old catalogs regarding control of Botrytis - it periodically runs rampant throughout gardens around the world, when favourable weather conditions persist. It can return again the next year if cleanup is not done properly.
I would like to give you with a little information on how to handle Botrytis in your garden, since I answered many, many calls and emails regarding this starting Summer & Fall (2008) and continuing today (2013). Those that saw Botrytis last year are likely to see it again this year if it is not handled properly. The horrible hail storm that devastated my gardens in early June of 2008 provided an excellent opportunity to experiment and take notes on what works the best. I had a huge risk of losing some lilies completely if Botrytis set in so bad as to travel down the stem and into the bulb, a real concern as damage was so severe from the hail. I fully expected Botrytis to destroy what was not already completely obliterated by hail, to my surprise it never happened.
So what did I do to prevent it from setting in? In desperation I dug out a recipe for a very old but well-known fungal spray referred to as Bordeaux Mix. I had not used Bordeaux before as I did not like the blue residue left on foliage as it dries, this time it didn't matter, the lilies already looked terrible and I had nothing to lose! The first thing sprayed was the potted lilies as they were the most forlorn looking, hardly a stem or leaf left untouched from hail damage. As time progressed I was amazed that not one of the stems sprayed developed a hint of botrytis all summer long, on those that had signs of it starting before the spray was applied it never progressed at all. I sprayed a patch of roses I'd been fighting with rust & powdery mildew for 3 years running, it worked there too, no sign of it all summer. All plants were sprayed once, the week after it hailed. Rain and cool wet weather continued for another month after the hail storm. At the end of the summer traces of the blue mix were still visible, but not botrytis, black spot nor powdery mildew!
No more chemicals and purchasing spray for me, I'll rely on good old Bordeaux, the simple all-purpose fungal spray which has been around forever, safer and far cheaper than anything else I'm sure. All the ingredients should be found at a garden centre, for sure at farm supply stores - I purchased mine at UFA in bulk bags. You can also buy Wilson's Bordeaux Powder where all you have to do is add water, it may not be as effective as making your own, but still more effective than any ready-to-use product you'll find on store shelves.
In closing, I must warn you to clean your beds well this spring if you had Botrytis last year, and be sure to spray the ground itself with either recipe below after you do. Here's hoping the weather this year is a vast improvement over last season for us all!
RECIPE #1 BORDEAUX MIX
- 3 1/3 tablespoons copper sulfate
- 10 tablespoons hydrated lime
- 1 gallon water
Dissolve copper sulfate in plastic or glass container with 1/2 the water thoroughly, leave it sit and come back later if you have to, it MUST be dissolved. In a separate plastic container mix the lime powder very well with the rest of the water. Slowly pour the lime mixture into the copper mix, stir thoroughly before use. Spray with a plastic sprayer, metal cannot be used with copper. Be sure to shake or stir up the mix as you spray so particles stay suspended in the water and do not settle.
If your plants suffer damage through the growing season or start to show botrytis spots, immediately spray with Bordeaux Mix.
RECIPE #2 COPPER SPRAY
In late Fall or early Spring before new growth begins, spray a solution (2 oz to 1 gallon water) of Copper Sulfate on the ground and all surfaces thoroughly. This should be used as a preventative measure against botrytis.
Copper Sulfate is often referred to as Bluestone. Hydrated Lime is the same as Calcium Hydroxide.
You will also find alternative recipes on our Fungicide Recipes page.