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csmlawn
08-15-2008, 02:21 PM
I've read here that the best time to apply herbicides for turf weeds is when the lawn needs cutting. Reason being is there is more weed present that can absorb the chemical. However, I asked my new lawn care contractor this question and he said right after a lawn has been cut. He feels that the blades are open and more vulnerable to the herbicide. He likes to hit the lawns no later then 3 days after a lawn has been cut.

You're thoughts???

RAlmaroad
08-15-2008, 04:05 PM
I've read here that the best time to apply herbicides for turf weeds is when the lawn needs cutting. Reason being is there is more weed present that can absorb the chemical. However, I asked my new lawn care contractor this question and he said right after a lawn has been cut. He feels that the blades are open and more vulnerable to the herbicide. He likes to hit the lawns no later then 3 days after a lawn has been cut.

You're thoughts???

Most weeds die from trans-location. Inthat they transfer the toxins to the roots where they cut off the supply of food from the stem and foliage. Or, the toxin can preform a growth inducer and the weed dies prematurely. Other herbicides actually burn the plant leaf cells and the plants dies from the inability to take in carbon dioxide and preform photosynthesis.
In any account, I prefer to have my clients mow three days before I apply any herbicide and not mow for at least 4 days after. Some labels even state it this way. I think Sedgehammer explains it in the label. A good clue is that the applications of a sticker means that the herbicide needs plant structure to attach itself.
My opinion, I know but I have no problems or grips from clients with weed kills. However, I'm on those lawns every month or less to check the water and irrigation.
You'll get conflicting opinions, I'm sure.

bug-guy
08-15-2008, 06:20 PM
i agree the more leaf exposed the more herbicide gets on the weed, the better odds of success. it a perfect world grass geting cut 1x a wk 3 days before or after cutting

junior091273
08-15-2008, 08:20 PM
I've had good results with Sedge Hammer with cut and uncut apps.

Great Product.

lilmarvin4064
08-15-2008, 08:35 PM
i agree the more leaf exposed the more herbicide gets on the weed, the better odds of success. it a perfect world grass geting cut 1x a wk 3 days before or after cutting

ditto. The goal is to wait till right in the middle between mowings or at least a couple days after mowing. But you're much better off spraying right after you mow, rather than mowing right after you spray.

when spraying nutsedge with sulfentrazone, I like to let it get tall.

americanlawn
08-15-2008, 09:11 PM
Best kill on weeds is when they are fully grown -- this way more AI (active ingredient) can be absorbed by the plant. Then wait 2 to 4 days before mowing or watering. Hard-to-kill weeds, wait 3 or 4 days. It is bad advice to mow off leaf tissue before spraying weeds. :hammerhead:

I've read here that the best time to apply herbicides for turf weeds is when the lawn needs cutting. Reason being is there is more weed present that can absorb the chemical. However, I asked my new lawn care contractor this question and he said right after a lawn has been cut. He feels that the blades are open and more vulnerable to the herbicide. He likes to hit the lawns no later then 3 days after a lawn has been cut.

You're thoughts???

rcreech
08-15-2008, 09:23 PM
Weeds should be actively growing and healthy when applying herbicides.

Now...if you are mowing HIGH, that makes a difference, but if you are scalping then I would say that your weed kill success will be limited!

I would not ever recommend mowing before spraying.

This is also why the label states to not mow 24 hours before or after an application!

If it made the product work better do you think it would state that? :dizzy:

kappa915
08-15-2008, 09:23 PM
I'm a 3 and 3 guy.

Treat 3 days after mowing, don't mow for 3 days.

RigglePLC
08-15-2008, 09:49 PM
I am not sure mowing makes any difference. But I have heard it is best to spray at night. If the weed control drys on the leaf before it is absorbed--it is never absorbed at all. I would like to see some university research on this.

On the other hand. Quicksilver (carfentrazone) and Dismiss (sulfentrazone) supposedly will not work in the absence of sunlight--also Octane. Do I have it right Shane?

lilmarvin4064
08-15-2008, 09:56 PM
On the other hand. Quicksilver (carfentrazone) and Dismiss (sulfentrazone) supposedly will not work in the absence of sunlight--also Octane. Do I have it right Shane?

you might be right on this. I know Scythe works much better in the sun, than in the shade.

tlg
08-15-2008, 10:28 PM
The more coverage on the plant the better the absorption. A weed that is actively growing is always going to be easier to kill. That being said, I can't say that a lawn mowed prior to a weed control application will really have a negative effect. The control products we use seem to give consistent results. The hard facts in all this is if you had to plan a days worth of production around who is going to mow and when nothing would get done. I might add that spraying for weeds on cloudy days is a plus for the best control and early morning or late evening when humidity levels are high will also help in getting a good kill. There are always ideal conditions and acceptable conditions. Some things are always beyond your control, mowing, weather, etc... unless you manage the property and are the guy who says go.

rcreech
08-15-2008, 10:39 PM
The more coverage on the plant the better the absorption. A weed that is actively growing is always going to be easier to kill. That being said, I can't say that a lawn mowed prior to a weed control application will really have a negative effect. The control products we use seem to give consistent results. The hard facts in all this is if you had to plan a days worth of production around who is going to mow and when nothing would get done. I might add that spraying for weeds on cloudy days is a plus for the best control and early morning or late evening when humidity levels are high will also help in getting a good kill. There are always ideal conditions and acceptable conditions. Some things are always beyond your control, mowing, weather, etc... unless you manage the property and are the guy who says go.

Good post! I agree totally!

If I come up on a lawn that has just been mowed I still go ahead with the app.

I just don't think I would recommend it, or do it on purpose!

csmlawn
08-16-2008, 12:05 AM
Excellent posts... thank you. :usflag:

RigglePLC
08-16-2008, 07:54 PM
What is more. Does absorption by the leaf have any effect at all? You can spray the leaves all day and not have much effect. Isn't it the top inch of the stem --the apical merestem--the only thing that matters? Actually the only thing you need to spray?

rcreech
08-16-2008, 08:43 PM
What is more. Does absorption by the leaf have any effect at all? You can spray the leaves all day and not have much effect. Isn't it the top inch of the stem --the apical merestem--the only thing that matters? Actually the only thing you need to spray?

Riggle,

Like your posts are we are usually very close on our thinking, but I don't think so!

Surface area is king! The more leaf you have....the more AI you can get into the plant, the better the kill. This is why surfactants can become very important to break surface tension to get adequate leaf coverage.

I totally disagree with your statement of "You can spray the leaves all day and not have much effect." I am not sure where you get this.

The apical meristem is the newest growth of the plant and usually shows symptoms first, but it is not the critical entry point to kill.

I have never heard this theory before. Where have you heard this?

Just to make my point....go out to any broadleaf plant or landscape plant and put a bag over the top of it, and then spray the leaves on the bottom half of the plant and see what happens.

RigglePLC
08-16-2008, 09:05 PM
Creech,
Violets--are a weed where you can spray the leaves--but the stem is mostly underground where you cannot touch it. So difficult to control. I am thinking about trying your suggested experiment. I think know of some pokeweed that might lend itself to such an experiment. Cover the top and spray the bottom half. I suspect the petioles will bend back sharply.

Of course, carfentrazone directly burns the leaves--different chemistry.

rcreech
08-16-2008, 09:12 PM
Creech,
Violets--are a weed where you can spray the leaves--but the stem is mostly underground where you cannot touch it. So difficult to control. I am thinking about trying your suggested experiment. I think know of some pokeweed that might lend itself to such an experiment. Cover the top and spray the bottom half. I suspect the petioles will bend back sharply.

Of course, carfentrazone directly burns the leaves--different chemistry.

With systemic products, it really doesn't matter where it enters the plant, as long as there is enough AI to kill it (determined by the size of the plant and the amount of growing points). Of course the bigger it is, the more AI it takes.

Once the AI enters the plant it goes into the xylem and phloem and goes to the roots and tip of the plant.

You care correct that Carfentrazone is a little different as it is a contact product.

grassguy_
08-17-2008, 12:03 PM
Leaf tissue and herbicide contact are the key issues. As Rcreech indicated leaf surface area is paramount. In most cases the best time to spray is when the grass in tall but not to be mowed for 48 hours afterwards. Reality is this scenario isnt reality in most cases. However, there are exceptions to spraying when the grass is tall also. If the weeds you are trying to control are low growing, (eg. ground ivt, wild violet, spurge,speedwells, etc) then spraying a day or so after cutting usually the best option, ensuring that you are getting the best herbicide contact possible. So it depends again on what you are trying to control and the status the lawn is in when you get there.

ArizPestWeed
08-17-2008, 01:11 PM
there are some in the dark here , more common sense needed , experience .

those of you who believe that mowing first and then treating for weeds are simply wrong .
more green leaf surface , more herbicide absorption for better kill.

something important on one has mentioned , mowing grass with weeds over and over can make a very health root structure with little leaf matter above ground , meaning , the leaf to root relationship will be way out of balance.
meaning , may not be enough leaf matter to absorb herbicides for a good kill because of a very developed root system

rcreech
08-17-2008, 01:48 PM
something important on one has mentioned , mowing grass with weeds over and over can make a very health root structure with little leaf matter above ground , meaning , the leaf to root relationship will be way out of balance.
meaning , may not be enough leaf matter to absorb herbicides for a good kill because of a very developed root system

VERY GOOD POINT!

Thistle comes to my mind first!

jspray
08-17-2008, 11:54 PM
More weed surface gives more herbicide take-up. A true cut-surface application would be more effective probably as neg. pressure would pull solution in. This has to be at the time of cut--some equip. has tried this but was plagued with various mechanical failures.