Soil fungal diseases are plant family specific which means they will not affect plants from a different family. Most soil borne fungus will not survive winter freezing but fusarium will persist for up to 8 years. There is no home owner chemical method of soil sterilization. Solar sterilization is one method that has been used successfully by home gardeners. Use clear plastic film over your garden for one year. The heat built up under the plastic will kill ALL soil organisms so you will need to add clean compost to the soil the year you begin planting again. This may be your best bet although your raised bed method above will probably work.

What is your soil like now?
How much organic matter is in that soil?
There is lots of research that shows that plant diseases can be suppressed if the soil is made not a good, healthy soil. I am hoping that you User Name indicates that you are in Pennsylvania so you should contact your local office of the Pennsylvani State University USDA Cooperative Extension Service to find out about having a good, reliable soil test done that will tell you about your soils pH and base nutrient load and along with that soil test you can dig in with these simple soil tests to get a good idea of what your soil is now and what you need to do to make it better,
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

Whether raised beds will help or not depends on what you put into those raised beds.

Here is a link that might be useful: PSUCES

Thanks for your replies. I currently use black plastic as a mulch. Also, my neighbor's tomatoes are literally 20 feet from mine...they are huge, green, lush and thriving. We get our transplants from the same nursery, so the plant source is not the issue.

As for current soil conditions, they are typical for western PA. Clay-like. It clumps together. But there are tons of earthworms in it. I add cow manure each spring along with peat moss. I have never tested the soil.

For what it is worth, I do also battle cucumber beetles each year, as well as jap beetles. But they seem to confine themselves to my cukes and eggplant.

If I were to replace the soil in new raised beds, I'd have soil/compost brought in from our local/reputable nursery.

Purchasing soil from someone in your area means that you will most likely get the same soil you already have, and why pay out money to get what you already have?
Peat moss is a non rewnewable resource, and you have readily available to you every fall lots of material that is better and cheaper than peat moss, those leaves from the deciduous trees that I have seen growing all over Pennsylvania. Plastic over soil prevents the soil from breathing which means the soil can become anaerobic and that is an environment that plant disease find really great. Manure should only be added to soils in the fall adn manure should always be composted before being added to soils because of the potential for disease pathogens in that manure.

Your last message may well have listed your problem. Fresh manure is very acidic and high in nitrogen. High N will cause root rot and that will cause the symptoms your described in your first post. Stop spreading the bull for a year or two and when you add it in the fall make sure to rototill it in at least 8 inches. I suggest you use a layer newspaper covered with grass clippings as your mulch. This to can be rototilled into the soil.

The vast majority of studies I have seen on the pH of animal manures is that they tend to be alkaline, not acidic. Where pH is given it ranges from 6.8 (slightly acidic) to 8.5 (quite alkaline).
That the soil tends to clump together is not an all bad thing since you do want it to do that, kind of. But if the soil clumps and does not easily fall apart that is a problem and indicates there is not enough organic matter in that soil. But a good, reliable soil test is the place to start.

The studies you refer to all used fresh manure from mostly feed lots who's feed contains significant amounts of calcium carbonate. Aged manure from dairy farms comes from animals not fed high CaCO4 diets thus not making it a pH problem. All the articles and scientific abstract I have read (15) show that fresh manure will raise the macronutrient availability in the short term.

So, to get back to the original topic, I stand by my recommendations in my post of Jan 4 with the deletion of "very acidic and".

westpagrower - is your neighbor with more successful plants also using black plastic as mulch? Our climates are different but black plastic wouldn't contribute to a healthy soil here. While it can warm the soil by a few degrees in Spring giving you a slightly earlier start, if you've had rain it can keep the soil under it too wet preventing adequate aeration for good root systems.

Another part of your plan that might cause problems is the use of landscape fiber and gravel. In very short order, the cloth will become clogged with the fine particles that wash down from your soil along with the percolation of water. I think that you will be very unhappy with the results.

Wow, great responses.

No, my neighbor doesn't use black plastic...or manure for that matter. He has a smaller garden, only about 10 tomato plants and that's it. He uses fertilzer...not sure what. Also, he's retired and has the time to weed his garden regularly. My garden is 4x the size of his. No way I could keep up with weeding all year while working and chasing two kids. That's another reason why the raised beds interest me.

The manure I use isn't "fresh." It is bagged stuff from Lowes.

Think I'm going to give the current garden one more year...no manure in the spring per your advice...add as much organic matter as I can, and see what happens. Also been reading about this Rootshield stuff that has been getting some good results for some folks. Going to stick to black plastic, though. Garden is 15'x 34'. I just can't keep up with the weeding otherwise.

I'm not real sure that a plastic covered soil would be an ideal environment for the beneficial fungi. Why don't you call or email the company that makes Rootshield (Bioworks) and ask them what they think?

Not what you want to hear, but you aren't having good results now - I'd skip the plastic products or any kind of man made landscape weed fabric completely, mulch with something organic to keep weeds down. I know there are times in your life where you have other priorities and rightly so, but you can make short work of annual weeds with a hoe if you spend just a few minutes each week on them , leave them in place for the sun to dry out.

I don't think composted manure from Lowe's is causing your problems. When I need more compost than I have on hand (top dressing beds every Spring) I buy the blended one at Home Depot ($1 per bag) - aged wood chips, steer manure composted to the point it smells almost like soil. If what you are buying is very wet and heavy, quite smelly, then it's too fresh and you might want to change brands. I've bought scores of the bagged stuff over the years without anything but good results - if you can't lift the bag and carry it easily without hurting yourself, it's too wet and new :)

West, you didn't specify just what kind of problem exists in your vegetables. What are they doing?...Or not doing?

Vegetables, for the most part, do not like a heavy soil, they prefer a more loose, toward sandy soil with lots of organic matter. As mentioned before, not too many vegetables like being fed too high of nitrogen. Compost is usually made up of such high yield of nitrogen.
So where it matters, keep compost part of your soil down to a minimum. Mix it in well with the soil well before planting time. Let it help fix the soil, while losing its nitrogen.
Do mulch your garden beds to conserve moisture--but do make sure your beds drain well.

Since you evidently have had problems for 3 years past, how about thinking "containers". There isn't much type of vegetable that cant be grown well in containers. Best of all, you can put the containers where the sun's advantage is good for the plant.

There are friends of your vegetables that will gladly assist you in seeing they come to fruition.

Marigolds can draw pests sway from a vegetable garden.
Make it far enough away so that the pests don't find the garden and refuse to leave.
Certain crops do not get along well with others. Tomatoes are not friends with broccoli and so should never be planted near the other. Nor should you plant potatoes.

Nasturtiums should be planted with cucumber and squash.

There are many other such friends and enemies of pests gardeners can use.

The only thing a raised bed will do is assist it in drying out and where wind may be a problem, will dry out that much quicker.
Make sure the raised bed is made of non-treated lumber.
But they do assist in controlling their moisture better.