I rotate daconil, neem and copper sprays on my tomatoes, but I wasn't using it until I saw evidence of disease.

Is there anything else I should be using that is available to the home gardener? If I am not seeing any signs of fungus, how often should I spray?

Fungicides are preventatives, not cures. Once the fungus has a hold on the plant the best you can hope for is to slow its spread. That is why application from day one of plant out is the standard recommendation.

How often depends on the fungicide you use and the directions for amounts of dilution and frequency of application is always on the label. Follow the label directions carefully for best results.

Per numerous discussions here, Daconil is the fungicide of choice for most effectiveness and weekly application is what is recommended.

Dave

Does the copper add anything of benefit to the Daconil? For my ornamentals, I always use more than 1 fungicide to help reduce the chance of resistance developing, so that is why I add copper and neem to the daconil.

No, it is just the opposite. Mixing various garden chemicals is never recommended since they can interfere with each others ability to work. By mixing ingredients you are diluting them and changing the pH and thus the ability of each chemical to bind to the leaf. You end up with spotty coverage, spotty protection

Either pick one and stick with it or if you feel you must, alternate them weekly. But don't mix them together. And note that testing has well documented that neither copper or Neem is as effective at control of p.infestans or a. solani as Daconil is.

Dave

Treating the soil with fungicides early in the spring may eliminate 'some' of the spores on the soil

*****

Dave, just noting that fungicides can't destroy intact spores that have dropped to the ground from previous infections nor just intact spores hanging around as possible new infections, as it were.

And just a note about how Daconil works as a fungicide.

THE cholorothalonil molecules cover the specific attachment sites on the upper leafe surfave where the two most common foliage pathogens could normally attach and intitiate infection, and those are Early Blight ( A. solani) and Septoria Leaf Spot. Thus blocking the ability of the spores to attach

Daconil has no action whatsoever against the two most common bacterial foliage pathogens, which are Bacterial Speck and Spot.

And Daconil is all that we home growers have that is partially effective against Late Blight ( P. infestans), which is often lethal/

So if you live in an area where fungal spores and bacteria are usually spread by air and rain it's best to start on a spray schedule as soon as the plants are set outside.

Are any treatments 100% effective, no, nothing in biology is usually 100% anything. ( smile)

Carolyn

I don't mix them together, I rotate them. Using multiple fungicides and rotating them (not mixing them) reduces the chance of resistance developing, just like with pesticides.
This is true if the different fungicides/pesticides have different mechanisms of action. If they have the same mechanism of action, then no.

If you don't mix them together, fine. As I said, alternating is your choice. But your earlier post sure read like that was what you were doing.

so that is why I add copper and neem to the daconil.

Thus my comments above.

Dave

Ok, just did a quick search and it looks like the copper does help with the bacterial diseases. However, there is some resistance to the copper and this can be overcome somewhat by using mancozeb, which I believe is not available to us home gardeners.

From the chart in the link below, it looks like neem oil has shown a benefit against the bacterial diseases. So I will keep adding the neem in the hopes of killing off any copper resistant bacteria.

I will keep using the copper and neem to help combat the bacterial diseases and the daconil to help combat the fungal diseases.

It's not perfect, I am sure, but last year I waited until I saw evidence of disease. This year I will pre-empt the little buggers by spraying from the start.

Should I start when they are seedlings or wait until transplant? It is pretty hot, humid and wet here so perfect set up for fungus and bacteria.

Here is a link that might be useful: Bacterial Spot and Speck

Ah, now I see I was confusing in the way I worded it.

I will spray the daconil once a week, the neem once a week and the copper once a week. These are going to be the world's most expensive tomatoes! But I am hell bent to grow some tasty tomatoes this year even if it bankrupts me. LOL!

I don't have the space to grow but 2 plants, so if I lose them, that is it for me. I need to take precautions to prevent that as best I can.

I guess I'm not communicating very effectively tonight.

I will spray the daconil once a week, the neem once a week and the copper once a week.

Hopefully that is not all in the same week.

I'd strongly suggest a careful review of the label instructions on the products. Spraying one day with Daconil, a couple of days later with copper, and a couple of days later with neem or whatever if that is what you are saying, merely neutralizes and washes off the previous spray not to mention wastes money and encourages problems as the leaves are wet too often.

Alternating fungicide products is not a standard procedure and I'm certainly not advocating it. Nor is there any evidence to support tolerance or resistance build-up with fungicides as there is with pesticides.

As I said, using multiple products is your choice. However if you feel you must then barring heavy rain only one product is applied per week. Sorry I don't know how to say it any clearer.

Should I start when they are seedlings or wait until transplant?

I think both Carolyn and I answered that above.

Dave

PS: aaaaaa - my apologies for the thread hijacking

Dave--no problem, as long as it is reasonable discussion.

I am really unhappy with my tomato plants this time. Fully fungus infected. I did get good quality/quantity fruits though.

Yesterday, I pulled out 3 tomato plants from roots.

Anna

"Nor is there any evidence to support tolerance or resistance build-up with fungicides as there is with pesticides."

This is not true. Not only is there abundant evidence that fungi develop resistance to fungicides, one of the recommendations is to alternate fungicides with different mechanisms of actions to reduce the likelihood of fungicide resistance.

Daconil has a lower risk of inducing resistance than some fungicides since it has multi-site activity, but the risk is not zero. See the article linked to here discussing botrytis resistance to daconil.

http://www.springerlink.com/content/q3043555764x438q/

And Bayer's fact sheet discusses this problem.

http://www.bayercropscience.com.au/resources/uploads/label/file7420.pdf

As noted, if you use the same fungicide repeatedly, the risk of resistance increases due to selection of those organisms that naturally have resistance to the fungicide.

There is a wealth of literature written on fungicide resistance. The more we use the same fungicides (and anti-biotics and pesticides, too), the more we select out for the resistant organisms. We have seen this phenomena happen time and time and time again in human medicine. The same is true when fungicides are used in plants. So far, daconil has shown low rates of resistance, but as the article on the Chinese greenhouses shows, low rates are not zero. And in time, the repeated use of the same fungicides will select out for the resistant organisms as has happened so often in the past. That is why it is recommended to use multiple agents with different mechanisms of action.

See link below if you would like to know more.

Here is a link that might be useful: Fungicide Resistance

I am really unhappy with my tomato plants this time. Fully fungus infected. I did get good quality/quantity fruits though. Yesterday, I pulled out 3 tomato plants from roots.

Anna - do you know for sure which fungus? I could assume Early Blight since p. infestans usually doesn't let the plants live long enough to get much from them. And yes, in much of the country this has been a bad fungus year thanks to the unusual weather. Was your weather abnormal?

Would any of the IPM recommendations I listed in my first post work for you? Is your garden surrounded by windbreaks or a fence or open? Sometimes even the smallest change in location or spacing or type of mulching can make a BIG difference.

I have one garden that gets steady continuous westerly breezes off the lake. Plants are planted N-S rows so the wind blows right through them all the time and it seldom has any disease problems. But another garden is shielded from the wind by the greenhouse and it often has disease problems just because of the poor air circulation there.

Are you plants in containers or in-ground? Can they be moved? Are there other nearby gardens that could be sources of contamination or are you fairly isolated? You avoid overhead watering, right? Remove all affected foliage ASAP?

Does any of this help?

Dave

Dave--It is a community garden. I only hope to have my own back yard some time.

My plot is fenced by chicken wire and is the end plot (there is no other gardens next to 3 sides of my plot). There was good air circulation in the begining of the season and as plants got bigger (thanks to all the heat we had) it kind of became overcrowded. However, I started noticing dried out brown leaves before it became overcrowded, say mid June. I removed the bottom leaves to avoid contact with the soil. But, it continued and became worst.
I totally avoid overhead watering. Oh, talking about the weather--it poured in the begining of the season followed by 90's + temps. Now it is little tolerable temps. Nothing different than what rest of the country is going through.

Next year I will be careful to spray fungicides, from the very first day I set them outside.

Anna

Great information here! I'm in southern NH (Zone 5, daytime temps now in about 76 plus or minus 3 degrees) on the north side of a wooded hill. Needless to say, not ideal for growing tomatoes but that's what I've got.

I've definitely had some early blight and possibly something else (bacterial spot?) which I'd been treating with daconil on a regular basis. But now that it's getting cooler and rainier, is it worth keeping up with the weekly spraying?

Thanks!

4H, just noting that Dacomil can help if you have Early Blight ( A. solani) but if you have one of the two common bacterrial foliage infections, as you mentioned above as a possibility, then Daconil is of no use.

THe only persons Iknow who continue to spray Daconil until the first killing frost are commecial farmers who are trying to prevent anthracnose lesions from forming on the fruits. When the night temps get cool as Fall approaches that's when it seems to be the worst in the general area where we garden.

In the meantime take off any diseased leaves that you see and dispose of them so that any spores and/or bacteria that might be shed don't have that much of an opportunity to do so/

Carolyn

Start your seeds in Pro-Mix BX with Biofungicide. According to the company hype the roots of the seedling become permanently inoculated with a special patented bacteria which fight fungus.
I believe it works, as I have had no disease this year on the 20 plants I started in this seed starting mix. I found it also prevents damping off of the newly sprouted seedlings. I bought four plants from the Fullerton Arboretum and Orange County Farm Supply and two of them have succumbed to disease already, so I don't know if its just coincidence, but I plan to keep using the Pro-Mix with biofungicide from now on since none of the plants I started myself have any disease, but half the ones I bought do have disease. BTW, you have to use fresh Pro-Mix BX with Biofungicide, I used some year old stuff and it seemed to have lost its anti-fungal properties, probably because the bacteria died after sitting around for a year.

Forgot to mention. Yes, you can have your soil fumigated, but you have to have a licensed professional do it for you, and I would guess for a small home garden the cost would be prohibitive, if they were even allowed to do it in a residential area. From what I read they cover the soil with a plastic sheet and pump poison gas in that kills every living thing including pathogens, fungus, virus, bacteria, microbes, weed seeds, insects, insect eggs, worms, living plants and weeds, etc.
After they remove the plastic you start with a clean slate. I believe strawberry farmers do this quite often because strawberry plantings are so hard to weed.

Thanks Carolyn for the information. I've really only started gardening last year. Before that, it was more of a Darwinian affair in containers. My thought was that we were in the tail-end of the tomato season here and it's just a race between getting more ripe tomatoes and the inevitable frosts.