Potato blight fungicide
Leigh Greenslade
Posts: 43
With many traditional fungicide like bordeux mixture now withdrawn what alternate preventative products are there against blight?
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Leigh Greenslade
Posts: 43
Leigh Greenslade
Posts: 43
Posts
Is Mancozeb still allowed?
I have used bordeux mixture for a couple of years but now can't buy it, I noticed a product in a very similar bottle which contained some sort of copper compound and made by the same company, I wondered if this could be used against blight as it didn't claim so on the bottle but bordeux mixture did have copper in it.
Copper sulphate is the copper ingredient in Bordeaux Mixture. That's the major reason for its withdrawal. What exactly is the copper ingredient in this product?
vitax copper mixture an inorganic micronutrient mix 2.8% copper 3% manganese 2.1% zinc.
Google says it's for deficiencies in trace elements so it won't do the job. Copper sulphate, the real thing, is a mixture of copper and sulphur. It can (or used to be able to) be sprayed alone. Just about every backyard tomato plant in Italy used to be bright blue, coated in copper sulphate. Many still are!
I wonder what the potato industry uses against blight?
There are any number of chemical fungicides. The best one I ever used - on tomatoes, against diseases like Early Blight, so it would work on spuds too - is a Chlorothalonil-based product called Daconil (although there are other brand names). It's a chemical but not toxic to fossicking insects. Some organic growers in the USA even look kindly on it.
It's available in the USA in volumes suitable for the home garden. A couple of years before I left Australia it was only available there in industrial quantities. A group of us tomato-growing friends chipped in to buy a quantity and we divided it up between us. Worked brilliantly. It's not available here in Italy in volumes for the home garden and, last time I checked, ditto the UK.
There are various Daconil (well, Chlorothalonil-based) products for different purposes - anti-fungal for toms and spuds, treatment for lawns, etc. The anti-fungal product is composed of 29% Chlorothalonil. That's the minimum figure. The other products with lower percentages aren't suitable.
I've been hunting around online. You can get it in the UK in domestic quantities but it looks like it's sourced from the States so I hate to think what the postage might be. It's not cheap, never has been, but it's 1 tbsp of concentrate per gallon of water so it lasts. I'll keep looking.
Thanks Italophile.