Thanks Michael for the great summary. Right now it is raining (I hope it will rain for several hours) so after it clears I will (need to )try this solution.

I made my way through all of the last thread. Thank you for updating this and for the info. Annie

It works! It definitely, positively works! I will apply it again on the coming weekend. Now, however it's time to try to locate calcium chloride for my roses - after the end of October I usually do not give them nitrogen, so I am a bit afraid that calcium nitrate would push new growth.

Thank you MichaelG for posting those papers and thank you for the summary. I truly appreciate it.

I'm going to try it as I have a few plants that consistently have ruined blooms due to botrytis. Thanks for your experiments!
Linda

It does seem to work, and if you aren't adding it to fungicide, it works to just spritz budding stems, buds, and flowers, especially the green stems below buds. As I understand it, calcium taken up by the leaves can't reach the flowers, but calcium absorbed by the stems can do so. However, it's possible that extra calcium in the whole plant might increase resistance to other fungi (no evidence for that).

I have been planning to SP Hawkeye Belle because 95% of the flowers are ruined by botrytis. I've been getting clean flowers ever since I started using gypsum solution. We have had some weather conditions that would spread the disease. Incidentally, symptoms seems to appear on the fourth day after wetting that is followed by cool to moderate temperatures.

On the other thread, I mentioned a fine filamentous material that sometimes "grows" at the bottom of the gypsum solution. This seems to be very fine crystals coming out of solution, and if shaken it doesn't clog even a mist sprayer.

Ceterum, why don't you use gypsum instead of calcium chloride? It isn't inconvenient if you follow the instructions in the original post. But you could probably find CaCl2 ice melter in the Piedmont cities during the winter months.

I checked for gypsum at Lowe's where they usually sell it in 3-5 lbs bags but they do not have it know - garden stuff is out, Christmas ornaments are in. I do not want to buy 50lbs at Farmers supply stores because I do not have space to store it. I was thinking to make a trip to Raleigh for C. chloride but I think they will not have it now and by the time they sell it, I will not have buds to spray. But I will figure out something, it really works. Maybe I will not even SP/give away Clotilde Soupert (among others)if I find an easy solution to spray her regularly.

In your climate, I doubt if you would have any serious consequences if you continued with the calcium nitrate. I'm very glad to hear you feel you got positive results.

Wow,thanks for the info. It is too late for this year here-well I suppose Clotilde Soupert will ball a few flowers yet- But I will difinitly try this next spring. botrytis has to be the worst problem here...

patricia

Ceterum, what exactly did you do with the calcium nitrate fertilizer? How often? How are you judging the results?

Michael, I am at the beginner stage. I filled up 7 or 8 one gallon milk and similar jugs with water added to the calcium nitrate per your instructions (2 teaspoon per gallon)* about 10 days ago or so. First I tried to use a misting bottle (about two weeks ago) but that wasn't good enough because I could not spray/mist the climbers or some of the very tall HTs like Folklore, Impeartrice Farah, etc. Needless to say before I could follow up with the Rocket sprayer we had a sprinkle (didn't qualify to call it rain) the next night and the blooms of Marechal Niel, cl. Peace Imp. Farah, Elina and you name it balled terribly. (Not that I needed any sprinkle in that thick humid steam bath with regular dews every morning we had for weeks to see almost everything ball).

So, last weekend DH sprayed the roses with Bayer+ Response+Avid in the morning and when the roses dried of that treatment, I filled up the Rocket sprayer with the calcium nitrate solution with some dish soap added, and sprayed all roses - only the top third or where I saw buds and yes, even open flowers. I needed to bring a huge bouquet to the garden club on Tuesday and I was curious if some of the already open flowers would hold on from Saturday to Tuesday. They did and they didn't even look tired.
I also cut a few blooms for my desk - some were fully opened; I would not bother to cut flowers in that stage to bring in as a rule but I was curious.

On Tuesday I cut pristine cl. Peace blooms, Elina, Folklore, Imp. Farah and Buff beauty for the garden club bouquet and I enjoyed seeing Clotilde Soupert, Great Century with perfect, clean blooms. The wide opened Memorial Day bloom I cut Saturday evening lasted till today. The cl. Peace blooms that opened are in sharp contrast with all those that I had no time to deadhead yet and were not sprayed with calcium nitrate prior to Saturday.

I didn't check Marechal Niel but looking out my study now I see open, clean blooms; no brown 'mop heads', no red spots, circles or stripes on the newly opened blooms. And the buds of Belindas dream that opened after Saturday are not rotten brown but pink and healthy.

I am aware that this is not a long enough experiment to qualify it any way to call it 'scientific' but I was thrilled that I could see unblemished blooms at long last.

I didn't do any control this time because I was just sick and tired of seeing only blemished blooms in the last month or so. I know, I know that I should have but I just could not stand seeing any more rotten blooms. Sorry about that.

For sake of comparison: DH sprayed 25 gallons of Bayer and al to treat all roses, I sprayed 5 gallons of calcium nitrate, 6 would have been better and enough; because of the drought I do not have that many flowers as I should in mid-October.

* I expected that I should use a filter not to clog the sprayer but there was no need for that, the calcium nitrate dissolved perfectly.

Ceterum, since the calcium nitrate dissolves so much better than gypsum, maybe you don't need to be messing with the jugs. You could dissolve 4 TB in a half gallon and add it to your 5 gal of spray.

Yes, but I wasn't sure how well it would dissolve. When I made the first solution many weeks ago (after your first thread-post to use it for cut flowers in vase, I found a bit of sediment on the bottom; but I didn't wait enough plus I used too much, 2 tablespoon - not for a gallon but for a bit more than a quart. You may remember I terribly burnt the flowers with that stuff. So I thought I should be more careful this time and print out and follow the instructions step by step. Besides, I wasn't sure how much I would need. It is not a big deal to fill up several jugs anyway. I didn't store them in hot sun however.:-)

Michael, I'm wondering if you are comparing improved vase life in your flowers with ones that were in, say, a commercial preservative (like Flora-life, which is what I normally use), or with ones that are in only plain water. Or in other words, do you think it is worth it to add calcium to water that already has a preservative in it, or is that overkill (no pun intended).

I was comparing with plain water and so were the scientific studies. One study compared calcium with particular ingredients in standard preservatives, but not with the combination.

Michael,

Thanks so much for this info. I deal with an ongoing case of botrytis pretty much year round on some of my more suscepible roses in recent years. I will definitely try this.

SB Susan

bumping this thread seeing if Michaelg still sees this as a working solution for Botrytis?

Ceterum, is thios still working for you as well?

Where can one buy Calcium Nitrate, Sulfate or Chloride cheaply in bulk?

Any updates I want to try the Calcium Nitrate but don't want to buy a 50# bag if it doesn't work well.

I may have missed something, but there are calcium sprays you can buy - for tomatoes, say, and hydroponics. Are they impractically expensive? Excuse me if this was discussed earlier.