Not possible.

You can get help if you tell us what "a mees" means, what plants it happened to and more.

The more is what you did. And this part takes a lot of Q&A because you and the person(s) who try to help you.

Some things that MUST be discussed are these:
- soil prep before planting
- planted what size plants, what kind, and when
- fertilizer? what and when
- water - method, how much, how often

I meant a mess. lol. I think I have some leftover disease in there from the nj tomato blight from a couple years ago and possible other diseases. Head doing this helps. I mainly grow tomatoes. I water often, all organic, no extra chemicals. Miracle-gro soil, water, sun, and love.

How do you purpose to "sterilize" your soil? Covering it up with something, usually plastic, is called "solarizing", but is normally for killing weeds & grass. I don't know that there is a way to actually "sterilize" your garden, short of digging all the dirt out, baking it in the oven, and putting it back. I suppose you could run it through a UV sterilizer too, but either way, you'll be putting it right back into the unsteril ground & air. I would suggest maybe trying a variety of tomato that is resistant to the diseases you are having trouble with. I would also suggest trying some sort of spray to protect and kill any disease.

I know you say you're organic, although Miracle Grow soil isn't organic unless it's specifically the organic type. Regardless, going 100% organic sets you up for disappointment, and people who choose to do so must expect problems with insects and disease. I like to avoid harsh chemicals, and usually do, but when you have an issue, especially fungus and disease types, you're going to have to set your organics aside and break out the chemicals, or you'll be simply letting your plants die. I, and I'm sure many others, have tried the so-called "safe/organic" types of products, and they simply just don't work.

Joe

read various places online covering the soil tightly and letting it bake can sterilize, or as you put it solarize to kill off any remaining diseases. or bring the soil close to day 0, per say.

Surely solarization will reduce blight. The OP has basically not rotated and can not rotate, because it is mostly tomatoes every year. The problem is that solarization in winter will not work at all, at least in MI (I suppose there are Zone 6 areas in AZ where it might work).

Since blight enters a plant through the aerial parts, one possibility would be to cover the garden in black plastic during the next growing season, and plant through holes. It would certainly benefit the tomatoes. Another thing that helps a lot with blight is drip irrigation.

I do add more ground leaves in the fall and more soil in the spring, and turn and mix everything over before and after the growing seasons.

Also, any chemical recommendations for next yr?

You can't sterilize your garden in winter. You're probably thinking of solarizing it, but you have to do that in the hottest part of summer, and it takes four to six weeks. Below is a link from Davis University explaining how to do it properly. There are no shortcuts.

If the late blight (Phytophthora infestans) that has been causing a lot of trouble the past two years is what your problem it, solarizing may help, but you won't have a garden next year.

Technically, late blight is not a fungus but a protist, or 'water mold' causing a disease that thrives and produces spores in humid environments and CAUSES INFECTION ONLY WHEN FREE WATER IS ON THE PLANTS.

So, making a point of planting in the warmest, driest, sunniest spots will help prevent disease. And don't plant them too close together. The quicker the dew dries on your plants in the morning, the better their chances of survival.

Don't overwater -- stick your finger into the soil (down to your second knuckle) around your plants; if the soil is damp at your fingertip, don't water, they're moist enough. Try to use some kind of drip irrigation instead of spraying them, and don't let the hose splash soil onto the leaves.

Cleaning up all the contaminated debris in the garden and disposing of it (NOT composting it) off the property will help, too. Rotating the crops in your beds is crucial. Tomatoes, potatoes, eggplants, peppers are all in the affected family, so try not to plant them in the same beds more than once every three or more years. If you have any wild plants from that family (nightshade, any of the Physalis, datura and petunia nearby, get rid of them as they can harbor the disease.

But the spores that cause it are windborne. You can do everything you can, and still have the spores blow in from somewhere else. Infected plants have been found at garden centers.

Prevention is possible by applying a commercial copper spray or Bordeaux mix at least once a week when weather is humid or rainy, but BEFORE the disease attacks. Copper is accepted by most organic producers. READ THE ENTIRE LABEL, not just the mixing part, and follow it exactly. The pH of the water must be above 6.0, and more is not better.

Another possible preventative is hydrogen peroxide (cheap, and less toxic than copper), sprayed as a 0.5% to 1% solution. Regular drugstore hydrogen peroxide is 3%, so you would mix a pint bottle of HP with two pints of water for a 1% solution, or with four pints of water for a 0.5% solution. I think. Math is not my strong point.

But, really, you should get a soil test (ask your local Cooperative Extension Service/Master Gardener where) and use OMRI*-certified natural nutrients to bring it up to par. Healthy soil produces healthy plants. No, they're not totally immune to everything, but you'll give them a far better chance.

*OMRI: Organic Materials Review Institute. If a product is on their list, the product will have a small OMRI logo on it.

Sue

Here is a link that might be useful: UC Davis- Solarizing garden soil

There are many copper compounds that are used as fungicides. The most common is Bordeaux mix which is a combination of copper sulphate and hydrated lime. It is accepted in organic farming provided that the number of applications is strictly followed and a proper soil amendment is observed to prevent copper accumulation in the soil.
Bordeaux mix sprayMaterials needed to make a gallon mixture
3 1/2 tbsp of copper sulphate
10 tbsp of hydrated lime
1 gallon of water (4 liters of water)
Wooden stick
Plastic bucket
How to prepare?
1.Add copper sulphate and hydrated lime in water. Make sure to use plastic container.
2.Stir well using a wooden sick or ladle.
3.Protect self from direct contact with the solution.
How to use?
1.Spray plants thoroughly preferably early in the morning, in a dry and sunny day. In this way, the plants have the time to dry and the solution can not penetrate into the leaves' tissues
2.Constantly shake the sprayer while in the process of application to prevent the solution from clogging
Pest controlled
1.Flea beetles on tomatoes and potatoes
2.Anthracnose
3.Bacterial blight
4.Bacterial wilt
5.Black spot
6.Downy mildew
7.Late blight on solanaceous crops
8.Powdery mildew
9.Rust
10.and many other disease causing pathogens
Standard procedures for the preparation and application of homemade extracts
1.Read and follow the label instructions carefully. Ask for assistance from your local agriculturist office when using copper for the first time.
2.Monitor plants regularly and spray only when necessary as copper can accumulate into the soil.
3.Spray in the early morning or late afternoon.
4.Use utensils for the extract preparation that are not use for your food preparation and for drinking and cooking water containers. Clean properly all the utensils every time after using them.
5.Do not have a direct contact with the crude extract while in the process of the preparation and during the application.
6.Make sure that you place the extract out of reach of children and house pets while leaving it overnight.
7.Harvest all the mature and ripe fruits before extract application.
8.Always test the extract formulation on a few infected plants first before going into large scale spraying. When adding soap as an emulsifier, use a potash-based one.
9.Wear protective clothing while applying the extract.
10.Wash your hands after handling the extract.

I think you might be better off growing a cover crop for a year, and then switching for a couple of years to plants that are unaffected by the diseases you've had problems with. For example, you could focus on greens, or flowers. Pull up any volunteers as they emerge. Without a host, that should greatly reduce the number of blight spores (or other pests) hanging out in your garden.

That seems to me a more promising way to cleanse your garden, while keeping the beneficial worms, microbes, fungi, etc., than trying to sterilize it.

For example, the last couple of years I've had Septoria and early blight in one garden, so I just skipped growing tomatoes for a couple of years. Now my neighbors are calling to ask if they can pick some flowers or blackberries.

What's a good cover crop then?

There are a few mustard types that produce compounds that kill off many harmful organisms. Plan to grow them to a reasonable height, flail the vegetative growth, and then immediately incorporate the residue into the soil.

But just sowing annual rye in late summer will do wonders to the soil for the following spring. The rye will add lots of organic matter to the soil as well as loosen it and choke out many weeds. Just be sure to kill it or till it in before it gets too tall in the spring.

Cattle favas, sold as Banner by Territorial Seeds, is a good start. They will be winter-killed, then next year you can plant any number of greens or alliums or root crops, except potatoes.

FWIW I remember when I was a kid the farmers who grew tobacco would "burn their tobacco beds" every spring. A tobacco bed was about 8' x 20' typically with 8"-10" logs on the sides. The area between was piled with brush, straw, whatever, and set on fire and allowed to burn down. The tobacco seed was scattered, an area was reserved for lettuce, radishes, etc. A white, very tight netting was stretched over all and everything thrived. No weeds, no bugs. Maybe tobacco seedlings need potash or something, but it worked. That's about 50 years ago, with all the new imported bugs, disease, etc. who knows?

Our experience so far this year has been good despite late blight on tomatoes last year.

After removing tomato plants and fallen foliage as much as possible we sheet mulched at least 12-18" on the beds in layers of materials as acquired.

partially composted horse manure + pelleted sawdust bedding
alfalfa hay sweepings
chicken manure + bedding
shredded leaves
grass clippings
fresh horse manure + bedding
shredded leaves

Topped all beds with burlap bags.

In mid spring removed bags & replaced with black plastic.

We also laid new mulch in paths to fill in the trenches made by so much organic matter on the beds.

Tomatoes planted after Father's Day with no protection. Our weather was unusually cool & wet this spring, so I didn't want to bother with plastic stuff that stops air flow.

Mulched with straw not previously used in garden.

Watered deep & infrequently with soaker hoses.

Removed any tomato volunteers that sprouted as these are what harbors the blight.

We had a cooler summer until the past few weeks where it's been in the 80s. Most tomatoes are still in stages of ripening. The few we've harvested have been excellent.

There's a discussion on the Organic Gardening forum about soil concerns after late blight.