Too soon for preemergent weed control?

[swami7774]

I live on Cape Cod (zone 7A). We've had an unusually warm late winter, and I am already seeing weeds greening up and flowering(see photos). I've got plenty of Dimension left over from last year. Should I apply now or spot-kill visible weeds and wait?
Thanks in advance.

[g-man]

Swami7774:

The general guidance is to apply when the forsythia is blooming in you area. Others use the GDD tracker (http://www.gddtracker.net/?model=7&offset=0).

Here is the link to the Pre-emergent article in the site website: http://aroundtheyard.com/index.php?opti ... Itemid=117

Note to admin: the links in the FAQ are not opening the articles anymore. It just goes to the main homepage.

[PSU4ME]

Tagging along here - interested because it seems too soon for me to do the pre-M (i'm central MA) but i am seeing some movement from the lawn.

[swami7774]

Swami7774:

The general guidance is to apply when the forsythia is blooming in you area. Others use the GDD tracker (http://www.gddtracker.net/?model=7&offset=0).

Here is the link to the Pre-emergent article in the site website: http://aroundtheyard.com/index.php?opti ... Itemid=117

Note to admin: the links in the FAQ are not opening the articles anymore. It just goes to the main homepage.

There's a large section of forthysia right up the street. I use it as my guide for fertilizing. But I can;t remember seeing weeds green up this early. I also have Tenacity, which works very well but is slow-acting. Will either Tenacity or Dimension prevent me from overseeing?

[Pway]

I used it last year in three split applications. The first was March 10 and the forsythia was in bloom. The second late spring and third late summer.

[swami7774]

I used it last year in three split applications. The first was March 10 and the forsythia was in bloom. The second late spring and third late summer.

The forsythia around here usually begins blooming in mid-April.

[Pennstater2005]

First, I'll be watching a combination of the GDD tracker and the forsythia. Then I'll run some extremely complicated calculations which will be followed by self doubt.

Lastly, I will completely mistime my pre emergent application and sulk while I hand pull weeds for months to come.

Forsythia is the one with pink flowers, right?

[seiyafan]

yellow flowers

[andy10917]

Forsythia is the one with pink flowers, right?

Only if you think this is Pink


Here's my best superscientific, guaranteed to work approach

(1) set up a PC, tablet or phone near a window that has a view to a Forysthia bush
(2) bring up your very best GDD Tracker, and check it every 20 minutes
(3) when the Forsythia bush blooms yellow, turn off the stupid GDD Tracker
(4) go outside and apply Pre-M

[Pennstater2005]

Sarcasm, anyone?

[ndlutz]

Sarcasm, anyone?

I got it, for the record.

[swami7774]

Anyway...the consensus seems to be to hold off on the preemergent. But I feel compelled to use some spot weed killer(Weed-b-Gone) to zap the stuff that insists on coming up hale and hearty so soon.

[bernstem]

Will either Tenacity or Dimension prevent me from overseeing?

Dimension will prevent grass seed from germinating while it is active. You can seed after Tenacity applications.

[swami7774]

Will either Tenacity or Dimension prevent me from overseeing?

Dimension will prevent grass seed from germinating while it is active. You can seed after Tenacity applications.

Thanks, and thanks for ignoring my typo.

[NJDan]

I'm reading on the GDD tracker site that it says 80% of weeds germinate when the soil down to 2 inches is between 60 and 70 degrees. Their model predicts when the soil temp is at 50 to 55 degrees, as they believe applying premerg at that point gives it time to get into the soil and I guess provides some margin for error.

My question is why not just get a temperature probe and stick it in the ground? It's pretty cheap and easy to measure the soil temperature, which is what we really want to know, right? The forsythia method seems to be tried and true, but ultimately why not just measure the actual soil temperature directly?

[swami7774]

It's been in the 40s and low 50s here for about 10 days until today. Right now it's 19 with a wind chill of -1.
I have plenty of weeds already going to seed along the road. As soon as it gets back into the 40s I'm zapping them with Weed-b-Gone. I'll wait on the Dimension.

[Cam8n]

Following. I'm on the cape too!