Do pre-emergents reduce weed seed load?

[charlz]

I can't seem to find an answer in my searches on the web so I thought I would post here.

Do pre-emergents actually make the weed seed no longer viable? i.e it tries to germinate but dies due to the pre-emergent, or does the seed just sit there and once the pre-emergent wears off it can germinate?

Thanks,
Charles

 

[Chuck52]

Charles,

I couldn't find a direct answer to your question, but I did find that many pre-emergents inhibit a particular enzyme, and from the wording of the article and the fact that some of these same compounds can also be used as post-emergent herbicides, I think it is likely that the seed germinates before the inhibition occurs. That would suggest that the weed seed load for the sensitive weeds is decreased by the application of the pre-emergent, assuming the newly forming plant would likely degrade while its growth was inhibited. The degree to which the seed load is decreased would likely depend on the ground penetration of the herbicide, i.e. seeds below the level of penetration would not be affected if they did not germinate before the herbicide degraded.

Chuck

 

[rcowan]

Wow Charles

Great question for the AG department at the UoI or your local extension agent.

Or call my buddy Jim at Arizona Revegatation at 520.455.5780 he wrote a pretty good book called "Just Add Water".

 

[jimg]

From what I understand the seed sprouts into the hostile environment created by the pre/post emergent....which kills it. Im not aware of any that change the viability of the seed itself.

Additionally, I found that chems labeled for grassland control of weeds kills grass too. If the grass is less mature than a certain point (which varies some depending on chems) itll kill those too. So, if you replant a field w/ grass it needs to grow to a certain point of maturity before weed control chems can be added safely.

ETA: I agree that getting good info about ag chems isnt very easy. I found that visiting mfg sites is very good. They generally have application notes or the like online.