On 24/10/2010 11:40, Pam Moore wrote:
On Sun, 24 Oct 2010 11:32:50 +0100, "Pete"
wrote:

"Pam wrote in message
...
Why buy it now? The weather is already too cold for it to have a full
effect - applied at this time of year is a waste

Many of the more stubborn weeds inc. Japanese Knotweed are considered to
be more likely to be affected by poison if sprayed as they are winding
down for the year as they take the stuff into the roots.

But in September, not now. Now is surely too late.

Probably.

My feeling too. I don't know if autumn is the optimum time to hit the
more stubborn weeds or not. I am not convinced by the argument as
glyphosate is a potent traslocating weedkiller anyway. Letting these
vigourous plants grow unmolested all summer long strikes me as a great
way to have them bulk up their underground storage rhizomes ernormously.

I have always considered that the take up would be more effective on most
stuff, when it is growing
at it's most vigorous - late spring to early summer.

"THEY" say that the plant draws the poison down into its roots at the
end of the season.

I think it is questionable at best. There might be some advantage to
hitting it again before the first frost so that the plant doesn't get
the chance to move all the sugars from the top growth into the roots.

There seems to be a marginal advantage (cost wise and effectiveness) in
using a slightly more dilute hit on stubborn weeds than the label
suggests. That gives a bit more time for translocation before the tops die.

But AFAICT never allowing it to see the light without getting hit by
whatever weedkiller you happen to be using is as good as anything.

Regards,
Martin Brown