have you had problems in the past? if you're going to use it, you might want to use it before there are developing fruits. personally i only use true organic stuff..
copper fungicide is technically organic in the sense that it comes from the earth, but it is a metal after all and they can be toxic.

If your plants are outside, then it is time to start the spraying.

A local newspaper columnist recommends 2-4 weeks after transplanting. San Francisco Bay Area.

I don't care about organics. I grow clean and eat clean, but I'm not afraid of copper. Lots of stuff can be toxic if used improperly.

Technically organic in that it comes from the earth? Arsenic and botulism come from the earth, as do a raft of deadly plants. So much for technology and organics.

But that's interesting that the application time is asap after planting. Good to know.

Copper only works preventively, so it's best if you start spraying with it regularly before you see signs of disease.

There are OMRI certified copper fungicides and non-organic copper fungicides. Regardless, if you're washing the fruit before you eat it, the copper won't be an issue to your health via consumption.

The issues are

1) whether or not you use a lot (have a huge garden or farm) and are near bodies of water into which it could run off and hurt organisms that live in the water

2) how safe it is to expose yourself to it when you apply it

3) how much copper buildup you accumulate in your soil over time

Re: #2--With any kind of copper, I would wear long sleeves and gloves and shower after application.

Re: #3--Applied according to instructions, I doubt toxic buildup would happen in the average home garden. I think the issue is more prevalent in orchards and vineyards where people have been applying copper heavily for many decades or even hundreds of years.

Re: plant damage--some forms of copper are more likely to cause phytotoxicity than others. I use Bonide organic copper, which is a copper soap (copper octanoate), and I've never had problems using at full strength as stated on the instructions, even on very young plants. If your water is acidic or you foliar feed, be careful with copper, as it becomes more phytotoxic in acidic liquids.

If you're concerned, I find that Serenade works really well on the early-season crud like bacterial speck. I'm thinking this year of waiting to use copper until later in the season and sticking with Serenade for the earlier portion of the growing season. Of course, it depends on what plagues your plants in your garden.

I second: Fungicides are for prevention not cure for diseased plants. Start spraying regularly as soon as they get out . Also do it after rain ( when it stps raining) .

I have used Cu, Neem and Daconil . Never had any foliage disease except Gray Mold when the rain season started ( in PNW) in October. Then I switched to bleach spray.. By then my season was almost over. I just wanted to protect the fruits already on the plants. It did keep the mold on check until I no longer wanted to save my plants.

Sey

Thanks. It was cautioned about using Cu fungicide on seedlings, so I'm just repeating what I heard elsewhere. But yes, in order to use it as a preventative it needs to be used sooner, rather than later.

>I don't care about organics. I grow
clean and eat clean, but I'm not afraid of copper. Lots of stuff can be
toxic if used improperly.

Technically organic in that it comes from the earth? Arsenic and
botulism come from the earth, as do a raft of deadly plants. So much for
technology and organics.

But that's interesting that the application time is asap after planting. Good to know.

Arsenic does not occur in pure elemental dangerous form, it is the result of mining and purification of others metals (primarily silver).. and most people don't spray their plants with it.

was just pointing it can absorb into crops. there are safer alternatives that don't involve heavy metals, but hey whatever floats your boat if you considering growing and eating foods sprayed with metals as "clean"..

the term "organic" was/is used in the sense that it's not synthetically produced, not that it's not dangerous. it is obvious you have a peeve against the term "organic" so i'll leave it at that.

stevie: Arsenic does not occur in pure elemental dangerous form

There are no copper applications that are copper "in pure elemental form".

> heavy metals

Iron is a heavy metal. So is zinc. Copper, iron, and zinc are all found in your average multivitamin. Copper isn't going to hurt you in and of itself. Like anything else in existence, the dose as applied to a specific circumstance makes the poison or the cure... or the neutral occurrence.

> it can absorb into crops

How much it does depends on the plant species and the concentration of copper. There is no record of accumulation into tomato fruit at concentrations that are cause for any concern in correct use in the home garden.

> clean

"Clean" is a meaningless term in gardening and farming. We're talking about an activity in which applying feces to crops or substances teeming with microorganisms of all kinds are routinely extolled as an excellent practice. There is no "clean"; there is beneficial, harmful, and not-harmful, and much of how we determine that is not by expecting something as complicated as nature and biology to conform to our oversimplifications but by evaluating actual evidence as they apply to specific cases of what actually harms us and what does not, what is a safe dose and what is not, etc., and intelligently weighing the risks vs. tradeoffs.

> it is obvious you have a peeve against the term "organic"

It's rational to have a peeve against how the term is very frequently used. For instance, "true organic" is meaningless.

Agree with gorbelly. Even though I am organic gardener who was certified for many decades I find that some who argue for the cause carry the term to the extreme and mistakenly often make claims that simply aren't true. Sorry Steve but there is no such thing as "true organic stuff" and even USDA and ORMI recognizes that truth.

Even earth-natural products have been modified to some degree by either its location in the earth, its creation by nature, or its processing and use by mankind. Thus all the different classifications. Some are less modified than others but all can be detrimental if used inappropriately.

Dave

Well said. Thank you. Now, let's be clear. I am very sensitive about unnecessarily exposing myself to poisons, and I appreciate the concern of the organic community about this sensitivity. But the identification of everything that isn't earth-natural as a poison is simply naive. As I said, there are a whole lot of earth-natural things that are pretty ugly health-wise.

FWIW copper sulfate is a naturally occurring inorganic salt. That doesn't mean that it is healthy or unhealthy. But the toxicology of it is well understood, and it seems to be pretty benign.