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  #1  
Old 04-14-2001, 10:04 AM
powerreel powerreel is offline
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What is the lowest temp for a true kill on turf weeds with TriMec. I don't want to just burn rosettes.
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Old 04-14-2001, 10:32 AM
deinck deinck is offline
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Hi Powerreel
I don`t like spraying anything until temps get to 65 to 70 degrees and the weeds are actively growing.Hope this helps
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Old 04-14-2001, 10:23 PM
GroundKprs GroundKprs is offline
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Varies with the weed. General rule of thumb, ester formulations will be effective after gdd50 = 110, and amine formulations after gdd50 = 170. (gdd50 = growing degree days, 50įF base) It is not the temperature on a given day, but cumulative temperature averages to date.
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Old 04-14-2001, 10:42 PM
John DiMartino John DiMartino is offline
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As long as they are actively growing-temps will be warm enough.
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Old 04-15-2001, 11:51 AM
Skookum Skookum is offline
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Review you labels, not all are the same. I watch the weather and go from there. I like a few days of 60-70 degree day weather before and after a spring spray, trying to match what conditions the label reccomend.

Jim's mention of the GDD (Growing Degree Days) is the most accurate way to be sure of temp to spray for target weed.
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Old 04-21-2001, 10:14 PM
David Gretzmier David Gretzmier is offline
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I've found that esters work down to 35 degress, but you must have a week to two week level of patience. they work by generating abnormal cells , thus the curl. amines need 60-70 degrees, 80 is even better. Dave
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Old 04-22-2001, 08:58 PM
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ant ant is offline
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TO JIM AT GROUND KPRS:
it's nice to see a contractor talk about gdd (growing degre day)..... i think you are the first one on this intire forum that ever talked about gdd.
i though i was the only one that used gdd.
thanks again
anthony.


****do you think any university ever did a study on weed emergence useing a growing degree day model?
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Old 04-22-2001, 10:37 PM
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Avery Avery is offline
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Trimec makes a formula for colder temps. Trimec Super I think.
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Old 04-22-2001, 11:13 PM
GroundKprs GroundKprs is offline
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gdd is a nice model for general information. Unfortunately, life is not so simple, and the microclimate of the specific site you are managing is the key, not the weather service regional data. If you want to use gdd for a specific problem at a specific location, you would have to install a special recording thermometer to record the highs and lows for you at that location. I have seen weed and insect activity in one site 4 to 5 weeks earlier than you see the same weeds & insects in the region in general.

gdd useage is out there, but you need to look for it. Cliff Sadoff, Purdue entomologist, published a great guide years ago, and in it insect emergence and treatment regimes are related to gdd for many species.

Phenological associations are the way to follow gdd data. Since all of nature basically follows the influence of cumulative temperature, you relate a specific plant activity to undesireable insect, disease and plant activity. If you can associate the budding, flowering, or fade of flowers in a specific shrub to insect or weed activity nearby, you have a microclimate indicator without having to record temperatures. There are many associations to the various stages of bridal wreath (forget the name of book now, and it's not in right place on shelf). One such phenologic association here, crabgrass will begin to germinate after lilac blossoms fade, so don't sweat the pre-em apps you haven't finished until you see the lilac blossoms swelling.

On the original question of killing weeds, look at the dandelion. When one sees the flower, the weedkilling sabers are rattled, but will anything help now? The flowering is the reproductive cycle of the species, and how many things in nature will stand for interruption of this process? You can spray anything you want, and burn the heck out of the leaves, but the movement in the plant is all upward, shoving stored energy from the root to enhance reproduction. So you will not penetrate the root, and the dandelion will regrow. You must wait until the weather has warmed enough that the plant is going into vegetative growth and winter wax layer on cuticle has lessened, then an application will have a much better chance of killing the dandelion. Unfortunately this occurs after flowering. So do it right, and kill the dandelions in the fall, after they germinate, and you will have better success in preventing yellow flowers in lawn.

[Edited by GroundKprs on 04-22-2001 at 11:16 PM]
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Old 04-23-2001, 03:15 PM
Skookum Skookum is offline
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Jim,

Your Dandelion example is so true. My neighbor wanted me to treat his lawn last Summer. I told him "Let's wait till Fall and we will get them all". He was ever so skeptical all last Fall and Winter after we sprayed. A few days ago, the Dandelions bloomed everywhere. My neighbor came over and just went on about how he has no weeds at all in his lawn and last year his lawn was chucked full of 'em. Even I was impressed with the results.

I have a commercial account though that we sprayed last Fall as well, that this Spring looked like we did not get as good of results. I believe we got a total kill, but I attribute this Spring's few Dandelions to the fact that the adjoining property is a gas station that has the BEST 10,000 sq ft Dandelion crop you have ever seen! The area is like a wind tunnel and my account is at the end on the tunnel. It catches ALL the trash and I am sure weed seeds as well!
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