Scott's Crabgrass control (Halts / Dithiopyr) - when to use?

 I've read where crabgrass germination usually happens when the soil has
warmed to about 50 degrees for a couple of days (there are less precise
indications, something to do with forsithia blooming).

I believe that grabgrass germination conditions has recently (or will
soon) occurr in my area (SW-Ontario - climate similar to Detroit,
Toronto, Buffalo, Cleveland).

Here is a web-link to the specific product:

http://www.scottscanada.ca/index.cfm/event/ProductGuide.product/documentId/19ADB8116EB712C23F37186E06EAAA9E

So my questions with regard to this product are:

1) This product seems to contain the following components:
   - Dimension
   - Halts
   - Dithiopyr
  
   What exactly are those chemical components?  What is "Halts" ?
   What does each chemical do?

2) How does the efficieny or longevity of this product change
   or improve or degrade in relationship to rainfall after
   application?  Is some rainfall after application desirable?
   Will too much rainfall reduce the effectiveness or longevity
   of the product?

3) For how long after application will this product remain
   active or usefull at killing emerging crabgrass shoots?

 [wordwrap disabled for chemical compound names/numbers]

Lawn Guy said:


If you don't own a soil thermometer, you can generally time your
application
to coincide with the blooming of Forsythia (barring any sudden, early warm
spells).


Dimension:

IUPAC (1): S,S¡¬-dimethyl
2-difluoromethyl-4-isobutyl-6-trifluoromethylpyridine-3,5-dicarbothioate
CAS (2): S,S¡¬-dimethyl
2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate
InChI (3):
InChI=1/C15H16F5NO2S2/c1-6(2)5-7-8(13(22)24-3)10(12(16)17)21-11(15(18,19)20)9(7)14(23)25-4/h6,12H,5H2,1-4H3
Formula: C15 H16 F5 NO2 S2 (apologies... subscript doesn't work here)
Chemical family: Pyridine

Exact enough?


Scott's tradename for their pre-emergent.


Dimension: Selective herbicide (Dithiopyr) that controls crabgrass,
goosegrass, Poa annua, chickweed, spurge, henbit, oxalis, and other pests.


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 (4). Any physical
disturbance
of the soil will result in a degradation of the product's effectiveness, or
a complete failure of the product in that area.


Possibly.


With a proper application, about five months.


(1) IUPAC: The International Union of Pure and Applied Chemistry
(2) CAS: Chemical Abstracts Service
(3) INCHI: The IUPAC International Chemical Identifier
(4) Each time a seed below the barrier germinates, it pokes a small hole
in the barrier and a seed or seeds close enough to that hole /can/
eventually
penetrate it.
--

Eggs

-Give a man a fish and he will eat for a day. Teach a man to fish
and he will sit in a boat all day drinking beer.

 <Kicks Highwinds server in the shin>
<Reposts via Motzarella>
[wordwrap disabled for chemical compound names/numbers]

Lawn Guy said:


If you don't own a soil thermometer, you can generally time your application
to coincide with the blooming of Forsythia (barring any sudden, early warm
spells).


Dimension:

IUPAC (1): S,S¡¬-dimethyl
2-difluoromethyl-4-isobutyl-6-trifluoromethylpyridine-3,5-dicarbothioate
CAS (2): S,S¡¬-dimethyl
2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate
InChI
(3):InChI=1/C15H16F5NO2S2/c1-6(2)5-7-8(13(22)24-3)10(12(16)17)21-11(15(18,19)20)9(7)14(23)25-4/h6,12H,5H2,1-4H3
Formula: C15 H16 F5 NO2 S2 (apologies... subscript doesn't work here)
Chemical family: Pyridine

Exact enough?


Scott's tradename for their pre-emergent.


Dimension: Selective herbicide (Dithiopyr) that controls crabgrass,
goosegrass, Poa annua, chickweed, spurge, henbit, oxalis, and other pests.


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 (4). Any physicaldisturbance
of the soil will result in a degradation of the product's effectiveness, or
a complete failure of the product in that area.


Possibly.


With a proper application, about five months.


(1) IUPAC: The International Union of Pure and Applied Chemistry
(2) CAS: Chemical Abstracts Service
(3) INCHI: The IUPAC International Chemical Identifier
(4) Each time a seed below the barrier germinates, it pokes a small hole
in the barrier and a seed or seeds close enough to that hole /can/
eventually penetrate it.
--

Eggs

-Give a man a fish and he will eat for a day. Teach a man to fish
and he will sit in a boat all day drinking beer.

 Well, I guess that Motzarella doesn't like wordwrap disabled either. *sigh*

I concede. If you want to know the chemical makeup, Google it or do the
math. =)

 Eggs Zachtly wrote:


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).


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) ?


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/litorder.asp?filepath=ca/pdfs/noreg/010-20251.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?