Allotment Gardening Advice Help Chat
Growing => Grow Your Own => Topic started by: robbodaveuk on June 21, 2009, 23:10
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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.
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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.
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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.
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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
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Is this any help to you oldbean?
http://www.pesticides.gov.uk/garden_home.asp
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According to https://secure.pesticides.gov.uk/garden/getfullproduct.asp?productid=7915&pageno=1 it can be used up to 2013.
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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
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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 !
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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.
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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.
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No more rain dancing in hot weather then :wacko:
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! :(
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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.
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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. :( :(
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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
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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!! :(
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Im using this for the first time on my Toms as i lost 3/4 crop last yr, sprayed them for the first time today.
Is it ok to spray the stuff on my little green tomatoes ?
Or do i try to avoid them and just spray the leaves?
Cheers
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Spray the lot, just don't eat them. Forget the time period, check the packet!
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The packet says wait 7 days before harvesting outdoor tomatoes and 2 days for indoor. so I would guess your little green tomatoes will be OK by the time they are red.
I would always wash them anyway.
I
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After previous years I have 4 greenhouses planted up with tomatoes and just two outside plants that way should the dreaded B...... strike I shouldn't have too much bother disposing of them.
Such a shame as I think outside tomatoes may taste much better.
(My pack of Dithane still unused).
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Totally agree about the taste of the outside ones.
I've cut back to about 40 outdoor plants this year, the 100 last year was way too many to cope with the crop! Thanks to the Dithane though, I didn't lose one of them, whilst the other plot holders on our site of about 40 plots couldn't scrape one tomato between them.
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Congratualtions on what looks like being a great crop of tomatoes DD - seems (touch wood) to be a good year for them.
I was not so brave. Having lost around 40 plants for the last three years I decided to stick to indoor growing as disposing of all the blighted plants and fruit was a night-mare without anything more than a bike trailer! :(
I have never used Dithane 945 as the OH would sooner have none than eat anything sprayed with chemicals if we can avoid it.
But... not to give up altogether... I planted just 2 outside and they are having a ball! :)
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Well after last yr ive took DD advice and using the Dithane it was either that or grow something else i think.
I dont like using chemicals either but i want some toms! ive only got 15 plants in this yr so will see how we go.
So far so good fingers crossed ;)
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Well after last yr ive took DD advice and using the Dithane it was either that or grow something else i think.
I dont like using chemicals either but i want some toms! ive only got 15 plants in this yr so will see how we go.
So far so good fingers crossed ;)
I wish you luck - I was so fed up with trying to dispose of nasty black gunge I've almost given up so it's bound to be a good year for outside toms!! ::) :lol:
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For blight on tomatoes best is copper fungicide, no way would I use Dithane. Copper is harmless for small growers, sticks well to tomatoes and can be washed off using your fingers under tap. I am now beginning Nov harvesting half ripe toms to be brought indoors to fully ripen - the Cu even prevents them rotting indoors! For potatoes the only solution is not to grow lates, earlies have the best flavours and no blight! I am a retired chemist (not pharmacist) and know all about copper - if you dont have that disease where you cannot metabolise it, it is harmless.
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Most copper fungicides have been banned by the EU, for use in gardens and allotment (although I believe that organic farm are still allowed to use them)
Unfortunately this means we can't recommend them on the forum.
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The whole thing's a bit irrelevant anyway. The resurrected thread is over 7 years old and relates to a substance no longer available.