Garlic, onions crushed or liquified with water

I've heard of it but never tried it.

Apple Cider Vinegar in water

Vinegar is generally considered a herbicide, not a fungicide.

Bleaches or Peroxide in water

In the sense that bleaches and peroxides are non specific antiseptics, yes they should kill fungus along with bacteria, protozoa, microarthropods, and everything else.

Grapefruit seed extract in water

WTF? How many grapefruit have to go to the gallows to make a teaspoon of seed extract??? I've never heard of grapefruit seed extract.

actionclaw: I would try compost tea, using the pre-brew grow-fungi-with-oat-bran step. My general belief is that the best control for fungi are fungi, just as the best control for insects are insects. Drench the whole plant, especially the underside of the leaves. My success with this has been partial, i.e not complete. I await other responses impatiently. Regards, Peter.

Actionclaw: none effective that are organic and very few that are not. Your best bet is going to be with cultural controls indicated in the link below under, 'Management'. With most any crop, good cultural controls can often be very effective at at least minimizing pest problems but not always.

Here is a link that might be useful: Wilts

Any fungicide that you would treat your soil with, organically acceptable or not, will kill any fungus, including the Mycorrhizal fungi and other beneficial fungi you want, as well as any potential pathogens.
Soils that have these problems, according to organic gardeners around the world that I regularly correspond with, tell my that she best way to get rid of these problems is to build up a good, healthy soil. There are those that apparently have not gotten there yet, or maybe have not tried to get there yet, that have repeatedly told me that this does not work, but people in New Zealand, Ireland, Spain, Germany, England, Poland, Japan, and many other places I have forgotten about have made the soil they have into a good, healthy soil (it did take time) and did get rid of the disease pathogen.

I guess you can pour weak acids or bases in your soil to try to combat wilts, but IMHO that tactic is one of those where the remedy worse than the potential for disease.

Cultural controls, as stated above, are the best way to combat these issues, esp the below-ground afflictions (aside from purchasing VFF/VFN hybrids or grafting heirlooms onto VFF-VFN rootstock). As for the rhubarb leaf/stem issues, I'm with dchall.

Dan

In general for our tomatoes, I use ordinary corn meal on the surface of the soil on a monthly basis to ward off most fungal diseases. If something happens my first line of offense is to spray with milk at 3 ounces per gallon of water (hose end sprayer). Spray all surfaces of the plant and the soil. There is a hubub going around San Antonio's organic gardeners that ordinary shampoo will actually kill fungal diseases. Haven't tried it but the single most ordinary shampoo I've seen is Equate (Wal-Mart's house brand) baby shampoo. It is a lot more ordinary than Johnson's Baby Shampoo.

Neem oil, sulfured molasses & water, and chamomile tea are all natural fungicides.

Al

In general for our tomatoes, I use ordinary corn meal on the surface of the soil on a monthly basis to ward off most fungal diseases.

Interesting practice...I suspect, dchall, this won't work for wilts of Verticillium or Fusarium or some blights, as these soil-borne diseases are subsurface pathogens living in the soil and roots. Working corn meal into the soil when, say, double-digging or rototilling may give a better chance for protection against extant critters - not sure it will do anything against later infestation from infected plants...

Dan

Grapefruit seed extract is a natural ingredient found in many herbal body preparations, such as face washes. It is used as a natural preservative. not for fungus, but for bug infestions it might work, don't know.
Try a compost tea: place 1 gallon of well aged compost in 5 gallon bucket, fill with water, stir well, and let sit in warm place for several days. Strain using cheesecloth, put the tea into a sprayer, and apply tx in evening. Repeat every four days if needed. Or the baking soda method.

Dan, you might be right, or you might be wrong. The research on corn meal is not active that I can tell. The fungi you mention were not mentioned in the original research. Nandina has done some independent research on corn meal and might have some thoughts.

Novice-2009. Your tea method might do more harm than good. Have you read what is available at http://www.soilfoodweb.com ? Dr Elaine Ingham spends a lot of her time trying to keep the oversimplified tea methods out of print. If you changed your method to a simple dunking of the compost into the water and immediately using the water, then you have something. Allowing the water and compost to sit in a warm place for several days virtually guarantees that you will have stagnant water containing anaerobic microbes at the end.

dchall, I don't know for sure but thinking thru the pathogen life cycle indicates that surface treatments will be ineffective. I'd be interested to hear yea or nay.

Dan

Okay, dachall, you trapped me into this conversation. What follows are some of my latest thoughts and experiments.

I agree with you that cornmeal scattered at the base of tomatoes, peppers and basil every two weeks does help to ward off some fungus problems. Spraying with a cornmeal tea once a week also helps. That formula is 1 cup of cornmeal to a gallon of water, let it sit about 36 hours or to the point where it has a sweet, yeasty smell; strain through coffee filters, add a few drops of a surfactant such as lemon dish detergent with NO additives and spray early morning or in the evening.

I am now on my third year of trialing the Aspirin Technique for fungus problems on tomatoes, basil and peppers, although Kimm declares it is not organic. I figure that a baby aspirin a day is keeping half the world alive and that there is no harm in using it in the organic garden. That said...here is the formula and how to use it. Dissolve 1 baby aspirin (81 milligrams) in 4 cups of very hot tap water. Allow to sit for at least six hours, buzz with your hand blender, pour in hand sprayer, add 1 drop of lemon detergent with NO ADDITIVES (that means antibacterial junk) and spray in early morning. I begin this treatment when my seedlings grow their second set of leaves and continue the treatment once a week until frost. Suggest those of you interested trial this on a few tomato plants, whatever size they are presently. You should see it resulting in stronger plants with less disease problems.

Some thoughts re Verticillium Wilt that run against textbook directions. As far as I know there is no organic or inorganic treatment for it. As Dan points out above VW is naturally present in soils and enters a plant through broken/cut roots. The cultural wisdom of the ages says that when planting you should break up a soil ball and spread the roots. Do we really want to do this when planting those prone to VW? Rather, should we make certain that the soil ball is well dampened, handle it very gently so no roots are broken and gently tuck it in its new home? Would this method help to prevent VW of tomatoes, cabbage, dogwoods, maples, etc? Think about this. Suggestion...on a rainy day do a search for plants prone to VW and keep a list of those you grow so that you will be extra careful planting and digging around them.

Nandina, if Aspirin was still made from Willow Tree bark it might be acceptable as an organic remedy for something, but since all Aspirin today is a synthetic drug it does not have a place in an organic garden.

Aspirin today is just synthesized from chemicals derived in the lab, not in nature; otherwise there is zero difference in the product today. The constituents of the compound acetylsalicylic acid have not changed.

(Aspirin was first synthesized chemically from spiraea, hence the spir in Aspirin, easier than from salix at the time).

The chemicals react and break down just the same, regardless of origin. Chemistry is chemistry. Chemistry does not change.

Dan

If I judged one I must have judged 50 science fair projects using salicylic acid vapor on plants. I don't know where the students learned about it but they proved the benefit to me. One student in my last science fair went on to win the International Science Fair for determining that the salicylic acid activates an otherwise seldom used gene in the plant. When stimulated that gene helps the plant defend itself from disease. The mechanism by which that happens was not revealed. There was more to his research that won him the prize but that was part of it. Whether it is acceptable in organics, I don't know. Doesn't seem like it would be but there are several things approved that I would not be caught using. Aspirin seems much milder than some of the other junk out there.

If as an organic gardener you start to accept some synthetics where do you draw the line at what is accetable to an organic gardener and what is not. If Aspirin, a synthetic, is acceptable why are not the organophosphates and Carbamates?
Of course common sense should enter in and tell you that there are some "natural" things that you would not use, such as Arsenic.

Well, what about the large carbon footprint created by, say, shipping alfalfa meal in an inefficient truck to a poorly-insulated metal building? Then the consumer driving their beater truck in a single-destination trip to the metal building?

Or the carbon footprint on that dedicated plastic spray bottle containing dish soap shipped via Diesel truck and made synthetically that was consumed in a single-destination trip via SUV or low-mileage minivan or other some such vehicle?

How does that help the planet, as compared to 6 aspirin already in your house that increase your yield and save a vehicle trip?

Where indeed do you draw the line and who draws the line? If I go out and try Aspirin, does that negate my organic principles and my garden is no longer organic?

Dan