[robbodaveuk]

I have found a box of Dithane 945 that my late father had for the garden. I want to use it to protect against potato blight, now I know it is still on sale but are there any precautions with it or is it OK to use.

  Robbo.

[Salmo]

Now that Bordeaux Mixture is banned, due to the copper in it, the only weapon against blight available to the gardener is Dithane.

It protects the leaves from infection but does not kill blight infection already present.

Spray when there is a Smith period (48 hours when the temperature does not drop below 10 degrees C and the humidity is above 70% for at lease 11 hours in each of those days.) i.e. thundery type weather.

The spray will protect the leaves at the time of spraying but new growth is not protected. You should spray again after 14 days to protect new growth.

The alternative is to cut and remove tops when blight is seen.

[Paul Plots]

You can use it on tomatoes too.....

I'm not sure I will be spraying potatoes as there is so much foliage to protect. I prefer to cut the tops off, wait around 14 days and then harvest the spuds. This worked last time my spuds were hit. 

[oldbean]

Now that Bordeaux Mixture is banned, due to the copper in it,

Can you give a reference for this? I can find http://www.telegraph.co.uk/gardening/gardeningadvice/3344163/Organic-gardening-Kick-the-chemicals.html saying it's been banned, and http://www.letsgarden.info/gardening-tips/treatments/bordeaux-mixture.html saying its use is restricted to 6kg/hectare/year. It still seems to be available from web suppliers

[barney rubble]

Is this any help to you oldbean?

http://www.pesticides.gov.uk/garden_home.asp

[oldbean]

According to https://secure.pesticides.gov.uk/garden/getfullproduct.asp?productid=7915&pageno=1 it can be used up to 2013.

[Salmo]

Pleased for organic growers that Bordeaux mixture is allowed to be used until 2013. Not sure why copper sulphate, the main ingredient, is considered organic, but that is another topic.

Plastering crops with copper is not really desirable and bordeau mixture is one of those mixtures that likes to settle out and block your sprayer while you use it.

 I use dithane

[Aunt Sally]

Copper sulphate is very toxic and persistent in the soil.  We used to use it at the school I worked at to demonstrate soil polution (in the lab not the grounds).

I use dithane in preference !

[Iain@JBA]

I would now use the dithane every 7 days as the new strains of blight can take effect in less than 7 days. I spray mine every Sunday.

[zazen999]

I thought it was weekly once a Smith period had been 'announced'?

I am avoiding spraying this year but last year I was spraying once a week and managed to avoid it for ages, only to have chuck loads because of slugs. So, we are growing slug/eel worm resistant varieties this year.

[Paul Plots]

No more rain dancing in hot weather then 

Can't be doing with reading all the technical scientific advice unless it's on the back of a packet - Generally prefer to avoid using anything other than water and a few prayers - as well as my compost & tubs of chicken fertilizer.

Swearing under my breath sometimes works (well, hardly ever to be truthful)....

Not yet resorted to Dithane 945 but considering opening the packet for the tomatoes this year - 30 outside plants and it would be nice to pick more than 5 ripe fruit this year! 

[digga666]

If it's the yellow powder stuff i used it on my spuds last year...........waste of time, i sprayed every 10 days and they still got blight.

[Paul Plots]

If it's the yellow powder stuff i used it on my spuds last year...........waste of time, i sprayed every 10 days and they still got blight.

I don't think that is does any more than delay blight but gives a chance of the crop maturing..

.... or at least that's what happened when a neighbour used it on his tomatoes last year.

Mine just pegged-it  and such a pain having to dispose of plants and infected fruits.   

[heaphy]

Does anyone know to buy a box od=f dithane, rather than a little box with 6 sackets which will not do much, as I just used 9 sackets this evening, though I have about 800 potatoes plants to spray but becomes expensive at £3.90 per 6 sackets that I pay, if spray every week.  Anywhere i can get a larger box filled with dithane that used be available before.  Thanks. John

[Paul Plots]

Does anyone know to buy a box od=f dithane, rather than a little box with 6 sackets which will not do much, as I just used 9 sackets this evening, though I have about 800 potatoes plants to spray but becomes expensive at £3.90 per 6 sackets that I pay, if spray every week.  Anywhere i can get a larger box filled with dithane that used be available before.  Thanks. John

I bought one box last year and, although I have opened the box, I have not opened the sachets. I'm still considering whether to use it or not! 

I may spray the outdoor tomatoes this year but will definitely not attempt to spray the spuds - there are just too many and the foliage is huge!!

If they are blasted by blight again this year I will cut the tops off and leave them for a couple of weeks before lifting. It would simply be too expensive to spray so much - not keen on eating them if they've been sprayed either!!