[Anton]

Just been discussing the merits of my new potatoes with a fellow allotment gardener.  They flowered about three weeks ago (still some flowers left) and acting on your advice I am waiting until the tops start to wilt. My fellow gardener pointing out some green fruit growing and said I should pick them post-haste or all the strength would go into growing these fruit. True or false?

Another thing is I sprayed all my plants this evening with the copper mixture you have been talking about from time to time but it rained a few hours later. Do you think this nullified my spraying operation?

Anton

[ytyynycefn]

Well, ours (Juliet) are just flowering, and we've been eating them this week - lovely  

[WG.]

True or false?

Take off the fruit if you are worried but the tuber isn't going to give up any of its hard-earned nutrients

Another thing is I sprayed all my plants this evening with the copper mixture you have been talking about

Which copper mixture?  Who has been talking about ?

[Anton]

David,
I should have been more specific: Bordeaux mixture. There was a small reference to this when I joined this group a few months back. I referred to my potatoes having caught the lurgy last year after some rainy weather in August and problems with my tomatoes, one of the suggestions was to use the aforementioned mixture. I applied some about three weeks ago and then once against yesterday but as it rained like mad yesterday evening I'm wondering if any protection was washed away with the rain.

Anton

[WG.]

The lurgy being Blight?  I take no preventative measures against blight on early potatoes since they are ready before the local blight attacks (of August).  Perhaps this is different in Belgium?

The following would suggest that heavy rain did negate the effect.  You may wish to re-apply but too much copper in the soil is not a good thing.

Bordeaux Mixture:

1 Dissolve 100 gram of builders’ (hydrated) lime in half a standard (plastic) bucket of water. (About 5 litres).
2 Dissolve 100 grams copper sulphate (available at garden centres) in a separate half bucket of water.
3 Keeping the lime mixture agitated to prevent settling, pour it steadily into the half bucket of dissolved copper sulphate.
4 If necessary add enough extra water to make up a total of 10 litres. This is Bordeaux mixture. It is at its most effective strength when freshly mixed so must be used immediately or within a couple of days.
5 It is sprayed to completely cover the main (bare) branches of peach, nectarine and other stone fruit trees to help control leaf curl and brown rot disease. It is also sprayed over raspberry canes in late July for control of raspberry rust.

Bordeaux mixture colours the sprayed plants blue. The spray can withstand light rain. However a disadvantage with this mixture is that it tends to quickly settle so must be constantly agitated during spraying operations. The lime content also tends to easily block the fine nozzles of sprayers.

[Anton]

Thanks a lot for the advice, David.

Anton