Bacterial/fungal management for 1 acre farm

[ac21686]

My family maintains a small (at least, I consider it small?) farm next to our garden center and the last few years we've been growing produce and selling it at our nursery. It's proven to be pretty popular and while it's not a significant source of revenue for us, it's fun and kills quite a bit of time in late July and August, when store foot traffic really slows down.

The last few years we've been hit hard by bacterial and fungal problems, mostly confined to tomatoes. Everything else seems to get the usual (squash eventually going down to mildew, for example). I'm not sure about using last year as an example because it rained 3-4x as much as it typically does during the prime growing season and the tomato crop was an absolute disaster. This year we will be far more diligent about bottom pruning to mitigate some of that (hopefully we don't have a repeat), at the very least. From the pinned PDF, this is what I believe we've identified and observed:

Bacterial:

Bacterial spot (seems like the near constant downpours and humidity exacerbated this greatly)

Fungal:

EB
LB
Unsure about target spot vs anthracnose...they seem quite similar visually. Something I'm missing in the visual cues?
Fusarium wilt

We prefer trying to go the organic route, but the priority is making sure we have an effective disease management program in place (and we are fully transparent with customers about whatever we may use). We are starting to transplant the seedlings to 3 and 6 packs in trays, where they will remain until close to memorial day. What should be the plan going forward? Copper fungicide and mancozeb (we carry the former but not the latter...I'd say 75-80% of customers now are only buying certified organic products) are mentioned in the PDF, but when should we start? I'm afraid of spraying them too early (if that's possible) and harming the plants. Would a type of soil amendment of any kind help as well? Any help is greatly appreciated!

[Nan_PA_6b]

Wow, that's a toughie. Your garden needs a roof to keep the rain off. Removing bottom leaves is good, as is anything else that gets more air circulation: thinning out the branches to let air in, planting further apart, etc. Also something on the ground (garden cloth, wood chips, etc) to keep soil from splashing.



I haven't heard of seedlings being harmed by copper products, but someone with more experience should chime in on that. Have you considered Serenade? I think it covers leaves with good microorganisms so the baddies can't get in.

[biscuitridge]

Check out mycostop.

[Cole_Robbie]

A regular spraying of a light bleach solution might help. At low concentrations, bleach does meet the omri organic standards, at least the last time I checked.

[zipcode]

A greenhouse or similar is pretty much mandatory for any somewhat commercial tomato operation. Besides much improved foliar disease advantage, cracking and better aspect are maybe even more important.
Also, prune to one stem, keep proper spacing, make sure they get morning sun, and maybe consider a fungicide if it's always like this.

[bower]

You haven't mentioned how much of the 1 acre is in tomatoes.
I agree that some kind of shelter to keep (most!) rain off the leaves would make a huge difference. There are varieties that are disease resistant (to some things), and which you can find by trial and error, but if you want the freedom to grow any kind of heirloom you will be much better off to invest in some shelter. Does not have to be a greenhouse, even a top with no sides will help. How are you supporting the toms, and could that be adapted to provide some shelter? If you can't shelter, mulch to prevent splashback from the soil and increase your time investment in support and pruning to maximize air circulation. (I have read that bacterial spot can travel on wind and rain though, so without cover you are likely to have trouble if it is in your area).

Two summers ago I managed 50 plants in greenhouse for my friend's organic farm. One day a week (or half a day) for pruning and tying was enough to keep the majority of plants healthy to the end of season. The rule of sanitation pruning is of course take away anything diseased first of all, and secondly prune to keep the air circulation good. Most important IMO is that you must remove blossom ends when you do your pruning. The dead tomato blossoms contain substances that promote fungal growth, and when they fall on a leaf or stem or fruit stem, they begin the disease process. So shake them off, pick them off and dispose with your prunings in a compost pile away from the growing area. Note: not sure about bacterial spot which may survive composting - the fungal diseases require plant material to live so once the plants are rotted it is gone.
Another thing I have noticed growing organically, is that the plants need N when they start to ripen their fruit, and if you're not feeding them they will take it from the lower leaves. As they withdraw N they also withdraw immune support from those leaves, and whatever disease they are susceptible to, they will come down with. This can be forestalled by feeding them as ripe time approaches and keep feeding them weekly or biweekly as needed, fish fert or other.

In my experience, large beefsteaks are the hardest to keep disease free - maybe two reasons other than genetics (1) they really need that extra fert as they load up and start to ripen, because of the large fruit, and (2) the fruit shape that has a depression around the stem end gathers water/moisture and is perfect for mold growth. So you may have better results with hearts or other shapes that have no depression around the stem end.

[amideutch]

ac21868 This book should answer most of your questions. I bought it mainly for the Microbial applications info and the nature farming has excellent info on the bio side of the house.

https://www.crcpress.com/Nature-Farm.../9781560220831

Ami

[brownrexx]

Last year was horribly wet in the Northeast. I garden organically and to avoid EB I mulch heavily to prevent splashing of spores and soil onto the plants. I also make sure that I have adequate air circulation around the plants. Less plants and more air works for me. I also use tomato cages so no plants are laying on the ground. I still have to trim off the lower branches as they develop yellow spots of EB.

Last year I sprayed with a dilute solution of copper one time late in the season and I had nice tomatoes right up until the end of the season.

I didn't get as much production as in a typical year but I didn't have any more problems with disease than usual except that I had one plant totally die for unknown reasons early in the season. I think that it may have gotten injured in some way because I saw no obvious signs of disease and no other plants succumbed.

[ac21686]

Bah, I had written up a fairly long post with my appreciation for the information from each of you guys but I waited too long to submit and when I reloaded it was gone! My apologies, but thank you all for the information! I've looked into a bunch of options for disease treatment. It gets so busy at the garden center that inevitably this side project can get away from us sometimes, that's why we do not have any intention of much more $ investment in it in the form of additional greenhouses/shelter, though I recognize how much that would help.

I couldn't say how much of it the garden is tomatoes, but I would guess maybe 1/6-7th of it (they are planted in two different areas). I think at the very least, we will be far more diligent about pruning and fungicide applications (I will also look into the bleach solution as I've seen threads about here before) and making sure they get proper airflow as well. They are spaced at least 3 ft apart, probably a bit more, with the cherries and grapes being put up against a fence. Those do become a bit intertwined sometimes, but we've never had much of a problem at all with them, and still plenty tasty even with the heavy rains last season. It's the larger tomatoes that seem to be the worst, as mentioned.