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Old 06-02-2006, 08:39 PM
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Dale Wiley Dale Wiley is offline
B&B Tree
 
Join Date: Oct 2003
USDA
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The method of control by most pre em's is shoot tip inhibition. This is accomplished by various means, but usually there is a chemical barrier in the soil, and as the shoot tips try to go through they contact this barrier and are killed.

Most pre em's with turf labels for weed grass control are of this type. Cultivation and exposure to sunlight are real quick ways to deactivate most of these types.

They depend upon a continual barrier for control and if the barrier is spotty, or fractured, it usually reduces control.
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Western Sports Turf
Landscape Specialty Services
Wetland Restoration Nursery

Forest Grove, OR
503-357-7202 - Phone
503-359-9294 - Fax

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You know that on Judgement Day, all the gold and silver is gonna melt away ...

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