Copper is approved for organic farming and isn't toxic to humans in small amounts. The big debate is that it can build up in soil over time. I'm not sure about applying it though.

The argument that copper can accumulate in the soil over time does not sound to be of concern to me.

How much copper is there in a bottle of copper fungicide ? Its takes hundreds of gallons of solution to use it all up and in a backyard garden a bottle can last for years.

Copper and copper alloys are used in cookware and fittings that can get into foods and drinks more . JMO

Sey

Actually, there is about half an ounce of copper in a 32 oz bottle of Bonide ready-to-spray. Don't drink it! That's about 1 mg of copper per drop of spray. Maybe a tomato can accumulate about one drop worth of spray? The EPA says that one liter of water should have less than 1 mg of copper. So if you drink a liter of water, the EPA is happy with it having in it as much copper as that one tomato has on it. But yes, unlined copper cookware, especially with acidic liquid in it, is likely to result in more toxicity.

Copper buildup in soil is a recognized issue for farms that use it heavily. Coffee plantations do. But it takes a long time to seriously pollute the soil.

What specific product are you using? They are not all the same.

Dave

I bought "Southern Ag Liquid Copper Fungicide" from Home Depot.

http://www.homedepot.com/p/Southern-Ag-1-Pt-Liquid-Copper-Fungicide-100048940/100599149

While I am aware that metals can exist where they are mixed with other things like oxygen for oxides and nitrogen for nitrides, and that this uses up atoms that energetically would be looking for something to join to or cause trouble for, my water tests have a 3 ppb (billion?) trigger level for copper. I would trust but verify the component of copper for my own knowledge, and probably will in the winter when I work on some plums that have fungus. Right now I have had enough success with aspirin on powdery mildew to think I will use it for a while or until it cannot get the job done. There is always a problem to solve in the late summer.

Actually at least in Europe there is a limit of how much copper you can use per area per year in organic farming. And some tests in vineyward areas showed quite huge amounts of copper compared to normal soils (they are using it since a long time).

From what I know, the copper hydroxide products have a 3 day period until 'fruit is safe to eat'. Don't know why though, it sticks quite well to surfaces (which it should so rain doesn't wash it too fast), so not sure what exactly can change in 3 days.

There are different kinds of copper fungicides , that I have just learned .

The famous one is:

BONIDE brand. Its active ingredients are :

=== 10% Copper Actunate

=== 1.8% Metalic Copper

LIQUI_COP: Active ingredient:

=== Copper Ammonium Complex 31.4 %

The later is the one I have and use. It is recommended for may plants. For tomatoes it is said to be effective on :

Use for:

Bacterial Speck

Bacterial Spot

Early Blight

Late Blight

Begin applications upon emergence of seedlings or

immediately after transplanting. Apply at 7 to 10 day

intervals. When disease is severe, apply at 4 to 5 day

intervals. Complete coverage is essential for disease control

use 1 to 3 tsp per gallon of water