Copper Oxychloride - how effective is it?

[Tania]

Does anyone use this one? The label says "A fungicide in wettable powder form for use on vegetables, fruit, pine and fir trees for control of blights, mildews and leaf spot"

How does it compare with Daconil?

Should I go with Daconil or the copper spray for early and late blights?

Any advice is appreciated

[Mischka]

Copper oxysulfate product is manufactured by partially acidulating copper oxide with sulfuric acid. It is suitable for dry application to the soil only, either on its own or in blends.

On application of the granules to the soil, the copper sulfate dissolves, releasing fine particles of insoluble copper oxide. As copper oxysulfate is not fully soluble, it cannot be used in foliar sprays.

I foliar spray with chlorothalonil (Daconil 2787®) and believe it to work much more effectively than any copper-based product. :wink:

[Tania]

Mischka, thank you for the reply - I wish Daconil was available for home gardeners in Canada!

perhaps the copper oxychloride is more dissolvable? At least the label states so

[carolyn137]

Tania,

OK, I'll bite.

In your first post you asked if you should go with the Daconil and then in the second post said it wasn't available in Canada, which I think it still true.

And when you say early and late blights, are you referring to A. solani for early and P. infestans for late?

I ask b'c both can appear either early or late in the season and if you have true Late Blight, as in P. infestans, how have you been able to continue with your tomatoes?

Chlorothalonil ( Daconil) is about the only prep available to the home gardener that has even a wee amount of protection against P. infestans.

Have you considered Mancozeb, a Mg++ containing anti-fungal which is often recommended when Daconil is not being used?

Better that Kocide and the other Cu++ containing preps, according to most folks.

[Tania]

Carolyn,

Yes, I meant P. infestans for late - are you saying that when a label says 'for early and late blights' it might not necessarily refer to P. infestans? Ouch. So using any copper spray is not going to help??

Last summer I've lost all my late tomatoes to late blight (P. infestans) in mid-late August, and I didn't want this repeated this season! That was a lot of tomatoes to dispose of... the thing spreads in a couple of days and kills everything... (although last summer was cold and very wet, and that definitely helped the disease... Hopefully this summer will be better...)

Anyway, back to fungicides - today I was browing a local supplier of horticultural products (http://www.growercentral.com/index.c...9226567#128300) and came across both Daconil and Copper Oxychloride, so I was looking for the info how they compare - since the latter was definitely more cost-effective... However, when I called the guys later today they told me that they do not sell chemicals to non-commercial users! Sounds like I am not getting Daconil after all (however a commercial grower can get it in Canada??? )

I haven't come across Mancozeb yet, but I'll keep looking... Thank you for the tip!

[Mischka]

I think I might have not been as clear as I could have been in explaining how copper oxysulfate works.

Copper oxysulfate (Cu3O2SO4) breaks down into 2 simpler compounds; copper sulfate (CuSO4) and copper oxide (Cu2O)...the sulfate is water soluble while the oxide is not. :wink:

There are mysterious forces that could likely assist you in obtaining a bottle of Daconil up there in the great white north.

PM me if you want the details.

[Tania]

Mischka, it is me who has completely forgotten high school chemistry... your explanation made perfect sense to me (after I used my brain a bit more)

[carolyn137]

Tania,

Ignoring for a moment Mischka's mysterious Daconil ways, , a copper containing product could help with prevention of Early Blight ( A.solani), which can occur both early and late in the season, but it isn't going to help prevent Late BLight (P. infestans), and Copper containing preps simply aren't as good as Daconil.

And please remember that even Daconil isn't as good as some products such as Tatoo that commercial folks have to help prevent Late Blight, but it's the best of what we have for home growers. And it IS the best for Early Blight (A. solani) when used on a regular basis.