# Preemergent



## nhbaler282 (Oct 5, 2009)

How much premergent can be put out per acre and for how long. Does it hurt to keep putting it out year after year and how long does it last doing its job? I’ve been using it for a few years and hopefully it isn’t doing any harm


----------



## weedman (Jul 12, 2019)

Which PRE are you referring to?


----------



## nhbaler282 (Oct 5, 2009)

Simazene


----------



## weedman (Jul 12, 2019)

Simazine isn't labeled for use anymore in hayfields.

To answer the question, it is fairly short-lived, and after a few years use you can see resistance develop, especially In ryegrass. This will make it useless. Once resistance if present. It can take a long time to go away. I was working with a sod producer may years ago that had taken over a farm where simazine resistance occurred. After 15 years of not using it. They tried it again and still only got about 40% control.


----------

