Fungicide for Gray Mold?

[b54red]

Does anyone know if a copper fungicide or any other for that matter will work as a preventative for Gray Mold? It appears to be a disease that really likes to attack black tomatoes and I have been growing more and more of them and seeing Gray Mold much more frequently. I have found out over the last two years that Daconil just doesn't cut it down here when it comes to Gray Mold. It works great for preventing most other foliage diseases but really has come up short on this one. I bought some copper fungicide the other day and was thinking about applying it as a preventative soon. Our weather is no longer cool and the humidity is off the charts so Gray Mold will start showing up soon. The only treatment I have found that is effective is a bleach solution but it is more a stop the disease once it gets going treatment and not much of a preventative so a week or two later it comes back even though I keep the plants sprayed with Daconil.

Bill

[RebelRidin]

No first hand experience with it outside of strawberries Bill. Your question made me curious and I ran a search and found this sight talking about organic methods to control it in tomatoes. They do mention regular copper sprays as a preventative measure.

http://gardenofeaden.blogspot.com/20...on-tomato.html

and this from Royal Horticultural Society http://apps.rhs.org.uk/advicesearch/...e.aspx?pid=468

states more specifically:


Chemical control

• Copper-based fungicides (Vitax Bordeaux Mixture, Bayer Garden Fruit and Vegetable Disease Control) are approved for use on tomatoes. While they do not carry specific recommendations for use against leaf mould, they are likely to have some activity against the disease. Use as directed for the control of tomato blight
• Yields begin to be affected when severe leaf mould has been present for about six weeks. If the disease appears close to the end of cropping, then the use of fungicides is unlikely to give any benefit in terms of extra yield (but may help with the end-of-cropping clean-up by reducing the number of spores available for over-wintering)

[RayR]

Bill, Copper Octanoate is approved for Gray Mold, Bonide Liquid Copper Fungicide, SoapShield from Gardens Alive!, Concern Copper Soap Fungicide and some others. It sticks real well when dry and doesn't wash off easily in the rain which is a plus in your humid climate.

[amideutch]

Bill if you want to go the Biofungicide route a combination of the following have shown to be effective.

Mycostop Streptomyces griseoviridis strain K61
PlantSheild Trichoderma harzianum
Serenade Bacillus subtilis strain QST 713

Use as a foliar and as a soil drench as a preventative. If you don't hit them where they live they will keep coming back.

Ami

[b54red]

Originally Posted by amideutch

Bill if you want to go the Biofungicide route a combination of the following have shown to be effective.

Mycostop Streptomyces griseoviridis strain K61
PlantSheild Trichoderma harzianum
Serenade Bacillus subtilis strain QST 713

Use as a foliar and as a soil drench as a preventative. If you don't hit them where they live they will keep coming back.

Ami

Ami, I tried Serenade and still have a full quart of it left. It didn't work at all down here. Maybe our combined heat and humidity is just too much. I also used both of the others last year and it didn't make any difference that I could see. I did like them for my root development and am using MycoGrow this year as a root drench on all of my grafted plants. I find that the seedlings form more healthy plants with bigger root systems. I have been applying it when they are small and again not long before transplanting.

I never had Gray Mold til I started growing a lot of black tomato varieties. I have had it spread to other varieties a few times but it always seems to start with a black tomato or a GWR. I don't know why they are so susceptible but if I ever let them get too bushy and dense during very wet hot weather I end up with Gray Mold forming in the shadiest part of the plant on some of them and if I don't use the bleach spray to stop it quickly it spreads relentlessly. It is almost never a problem during the late summer and early fall when our very dry weather hits and the humidity drops a little. I have a friend who has never had it on any of his tomatoes but he does an unusual pruning method. He only allows two stems to form and sends them in opposite directions on a trellis so they get an inordinate amount of sunlight. I could never allow that much room per plant because I need many more plants started in the garden because of my high loses due to fusarium. That could be another reason I don't have a problem with it in the late summer and fall; I don't have that many plants left and they can spread out more on the trellis.

So far this year I haven't seen a trace of it; but I'm sure it is only a matter of time. I have one row of tomatoes planted rather close and they are getting a bit too dense. I planted them close because the rootstock I used on them is one from a fluke plant that I had and I wasn't sure it would have any fusarium resistance so I planted a whole row of plants grafted onto that rootstock expecting some of them to be gone by now from fusarium. So far it is turning out to be the most vigorous of all the rootstock I have tried and as a result my foliage is more dense on these plants and none of them has come down with fusarium yet. Even the hearts are getting downright bushy and I am going to have to remove some very large well established stems on them to open them up a bit.

Bill

[b54red]

Ray and Rebel, I think I will give the copper a try and see if it is effective. Maybe nothing will stop it down here and I'm certainly not going to stop growing black tomatoes but if the grafting works to give me some protection from fusarium then I will be able to give my plants more room in the future and that will take care of a lot of the problem.

Bill

[sfmathews]

Bill, I just purchased some copper soap this weekend and sprayed it last night after our rain had moved out. I didn't find the Daconil to be helping this year. Time will tell if the copper will slow down the mold and EB.

[Cole_Robbie]

I'm just guessing, but I would try hydrogen peroxide, diluted to about 1%.

[JamesL]

CR,
Peroxide will work to eradicate, similar to Bill's bleach spray. No good as a preventative as it breaks down very quickly and becomes just water and oxygen in a matter of hours at the most.

[RebelRidin]

Originally Posted by b54red

Ray and Rebel, I think I will give the copper a try and see if it is effective. Maybe nothing will stop it down here and I'm certainly not going to stop growing black tomatoes but if the grafting works to give me some protection from fusarium then I will be able to give my plants more room in the future and that will take care of a lot of the problem.

Bill

I don't blame you. I would not stop growing black tomatoes either!

[Paradajz]

first cases of total resistance of Botrytis Cinerea to chlorothalonil were registered in Europe 25 years ago.
as a matter of facts, this villain is an absolute Olympic champion in developing resistance to any fungicides that mankind keeps throwing at them.

as preventives: copper partially, mankozeb partially, propineb partially. you could try combinations- alternations of copper with one of the later ( propineb has shown slightly more effective results, but it really depends on the strain you have there ).

are substances like cyprodinil and fludioxonil ( Syngenta has it in ''Switch'' ), or any kind of boscalid ( BASF in plenty of combinations ) or fenhexamid available to you?
if those substances are available,
cyprodinil + fludioxonil + mankozeb is n1 preventive/curative combination, 2 x in 10 days period, and you should be completely relaxed about it.
if necessary, a single following treatment with boscalid or fenhexamid would close the season to the B.C. issue.
but, please note- what ever you use on it this year needs to be amended in the following one, cause this stuff really develops resistance in the speed of light.

br,
ivan

[lycoperson]

The best prevention is spacing plants wider apart and pruning for good airflow through the plant.

Botrytis really hits when humidity is above 93%, there is free water on the plant, and temperatures below 63F. In these conditions, the spores will germinate in 6 hours.

I personally have not had success with hydrogen peroxide (curative) or serenade (preventive). I have had the best luck with Cease, but that may not be available for home growers. Bioworks is recommending Cease with Milstop. Milstop active ingredient is potassium bicarbonate.

http://www.bioworksinc.com/products/cease.php

[efisakov]

I use on 1 gallon of water 1 tbs Epsom salt, 2 tbs lemon dish wash soap, 3 tbs baking soda.
I sprayed my toms (that works as preventive for many things), no gray mold at all. I did not spray my peony, many of them did not even bloom, this was so unexpected. Last summer in Nj was so creasy, as if it was not NJ at all, as if we were in some tropical area. I sprayed my peony later and they recovered partly, but the blooms were infected too mach. Peony leaved. This year they look great. Knock, knock...
It is an organic approach, try. It would not damage tomatoes.

[bower]

b54red, I'm wondering if you've ever found any black varieties that are more resistant to grey mold than others?
Could you tell me which ones you've found to be susceptible, as I was hoping to try as many as I can next year, to try and find the best contender, but maybe it would be a waste of time.

[b54red]

Originally Posted by bower

b54red, I'm wondering if you've ever found any black varieties that are more resistant to grey mold than others?
Could you tell me which ones you've found to be susceptible, as I was hoping to try as many as I can next year, to try and find the best contender, but maybe it would be a waste of time.

I have not noticed which black tomato plants get it worse or if any do. I'll try to pay closer attention in the future. I thought I was being fairly observant just noticing that the black tomatoes consistently got Gray Mold worse than others. My wife would be surprised I payed that much attention; but since it was on my tomato plants maybe not.

Bill