Eggs Zachtly wrote:

Dimension:

(...)

Exact enough?

I should have been more clear.

What I meant to ask was, is Dimension the same as Dithiopyr? (which my
recent research indicates that it is).

What is "Halts" ?

Scott's tradename for their pre-emergent.

Is "Halts" another name for Dithiopyr?

If so, then how come it's got so many names? How can (or why does)
Stott's use two trade names (Halts and Dimension) to refer to the same
chemical (Dithiopyr) ?

2) How does the efficieny or longevity of this product change
or improve or degrade in relationship to rainfall after
application?

It needs to be watered in to work. In a nutshell: You put down the
granules and when they come in contact with water, they dissolve,
forming a barrier. Germinating seeds can't penetrate that barrier

I think that's a corny and technically incorrect explanation. I have
found a better one:

-------------
The active ingredient in Dimension (dithiopyr) enters the
crabgrass plant through its roots, shoots, crowns and leaves.
The major site of physiological activity is within developing
plant tissues found in the growing points.The mode of action
is inhibition of mitotic cell division, or the inhibition of
cell development and growth.

Dimension must come in contact with young, exposed plant
meristems in roots and shoots.This explains the selectivity
between surface germinating weeds such as crabgrass and the
exceptional safety to established turfgrasses.
--------------

Source:

http://www.dowagro.com/webapps/lit/l...1.pdf&pdf=true

That information pertains to a liquid (sprayable) version of Dimension,
and not the granular version as sold by Scotts (that includes
fertilizer).

Given that this dimension must be solubalized (dissoved) in the soil to
the extent that it must be in contact with (and taken up by) the
emerging crabgrass plant, I don't understand the prohibition against
later raking or aerating (coring).

There is some mention that while the application time for Dimension is
very early in the spring, it's not necessarily the best time to be
giving fertilizer to your lawn. So I wonder why they incorporated
fertilizer into this product.

PS: I've been buying fertilizers and herbicides for my lawn for the
past 10 years (here in Ontario) and I don't think I've ever seen this
"Halts" product (or any crab-grass control product) for sale here until
last fall. Are these products (that includes Dimension, or "Halts")
relatively new for the home-owner market?