[wordwrap disabled for chemical compound names/numbers]

Lawn Guy said:

I've read where crabgrass germination usually happens when the soil has
warmed to about 50 degrees for a couple of days

True.

(there are less precise indications, something to do with forsithia blooming).

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).


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

[...]

So my questions with regard to this product a

1) This product seems to contain the following components:
- Dimension
- Halts
- Dithiopyr

What exactly are those chemical components?

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?

What is "Halts" ?

Scott's tradename for their pre-emergent.

What does each chemical do?

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


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 (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.

Is some rainfall after application desirable?

Yes.

Will too much rainfall reduce the effectiveness or longevity
of the product?

Possibly.


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

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.