Pre-emergent with Nitrogen?

hankhill – posted 28 September 2006 23:36

It’s getting about time to put the pre-emergent down. The one’s I’ve used(Dimension & Pre-M), have mixes available of the form 0-0-7 and also a normal (nitrogen containing) mix (perhaps 20-0-10?)

What mix should be used for an October pre-emergent? (St. Augustine…mid Texas)

[This message has been edited by hankhill (edited 28 September 2006).]

DoctorOfTheLawns – posted 05 October 2006 16:21

I would suggest little to no nitrogen. In the fall with cool temps and morning dew, the nitrogen will only promote brown patch. Which is a nasty fungus that will eat a St. Augustine yard alive, if it goes untreated.

hankhill – posted 06 October 2006 17:19

I heard that Brown Patch usually gets youonly in a certain window of nightime tempsthat occur in the fall. Above that range,in the summer, too hot, and below that range,in the winter, too cold.

Also, Brown Patch doesn’t hurt the stolons,only the blades, so assuming it happensduring dormancy when the stolons don’t needfood, it shouldn’t kill the turf. That ismy understanding anyway.

cohiba – posted 07 October 2006 09:12

Brown patch model:

Relative humidity(RH) + night time temperatures= 150 or greater.

Suppose RH is 90% and it stays in the 60 degree range all night. Then you can get Brown Patch.

I wouldn’t fertilize turf going into dormancy.

My two cents……………