On Tue, 24 Jul 2007 10:46:27 GMT, Pam Moore
Potato blight only affects potatoes and tomatoes, but it is just one
plant disease. I have just pulled up all my tomato plants today,
having already removed the tops of potatoes. Once it strikes it
spreads very quickly.
Does nobody know the answer to my question as to what spray is used by
commercial growers?

I have a feeling it's Mancozeb (a dithiocarbamate) and available to
the amateur as Dithane 945, mentioned by someone else in the earlier
thread. I've also seen copper (e.g. Bordeaux mixture) suggested. But
apparently neither completely kill the fungus, they just slow it up a
bit and delay it killing the haulms, allowing a better yield of spuds
themselves. Early attacks of blight are the most serious commercially,
presumably because the spuds themselves haven't yet formed by the time
the plant eventually succumbs.

Down here in west Cornwall they spray potato crops at least every ten
days when the weather is warm and humid.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net