What does the label say? Most of the products I use label says 3 days before or after a mow. Your supposed to follow the label.

I have sprayed after mowing with no I'll effects on control of weeds targeted.

Depending on product contact on leaf surface area is what gets the product into the plant. You cut off half or more of the leaf you just lost all that contact.

 

Ive cut down over grown beds to a couple inches high and then sprayed with gly many times and it has always been effective on any weed that has any green foilage left, grass's and ground hugging weeds mostly.
No experience with other hebicides.

 

That only works if there is the majority of the leaf system intact. High cut areas and weeds that are in a low rosette growth habit will have most of their leaf system intact. That changes if the turf area is one that is mowed low. I see it time and time again. Rather than do things logically, a low mowed lawn is sprayed at the same time as mowing. Does not work. Weeds continue to grow and be a problem.

 

I don't know for a fact (haven't done any testing or anything) but my understanding is that the wait is a combination of stressed turf (you just cut off a chunk of its blades) and less weed leaf surface area.

For the don't mow right before, I think the weed surface area thing has to be a lesser factor because it's not like they all grow much in a couple days. For don't mow right after, makes sense not to cut off weed leaf before the herbicide has been taken up by the weed.

Cutting releases auxins that cause the plant to grow. The plant thinks it is being eaten (ok, plants don't think but you know what I mean ). For turf, that stresses it and it may get banged up a little by some herbicides even if it's otherwise tolerant of it.

 

I've seen on here and other places where people claim that cutting English Ivy prior to applying, results in better kill than applying without cutting. This method suggests that since the leaf is waxy it is difficult to apply and have it stick & absorb, and cutting opens up the leaf for better absorption.

I never seen this claim on other plants & this might just be successful with some waxy leaf plants. Are Violets difficult to control due to a semi waxy leaf & would cutting and applying provide better control. I've read where applying late in the season is more advantageous for Violets since they are absorbing more at this point.

 

I have never noticed any difference due to mowing.
This needs a test. An experiment. I am thinking. The leaves don't really care. The rapid expansion at the tip of the weed plant is the area affected by the herbicide. The apical meristem is the site of the herbicidal action.

Grass doesn't really care. Grass naturally is eaten by cattle. Over millions of years of evolution--it has adapted to this. Cut the top--and a new grass blade emerges from the crown.

 

I'm no expert and could be wrong in theory, but in reality I've had success with cut and spray. Image cutting oneself and then dropping some salt on the wound. That opening allows it to get into that wound. I think the chemicals gets in there.

My theory is the company is concerned with the stress on the freshly cut grass, especially if not watered regularly, and the customer complaints as a result.

I cut my lawn at 4" so whatever weed that's in the lawn is still pretty intact after a cut. So, I cut and then spray, especially now. If I wait 3 days, I'll have a jungle on my hands with all this rain. I constantly cutting as it is.

 

Sometimes I have success with cut then spray afterwards or the next day. Typically I'll spray midweek and then cut by Saturday.

Kinda depends on what I'm spraying.

 

I always try and wait a couple of days before spraying. More leaf area to hit. I suppose the act of cutting may shock the weed into not growing actively? Could have some effect on chemical intake. Hafta ask somebody WAY smarterer than me.

 

Easy stuff, (dandelions, clover) will die no matter what. Harder stuff, (purple nutsedge, virginia buttonweed) I want every advantage I can get. Cut height and type of grass will play a difference too. It's one thing to cut the tip off of a 5" broadleaf weed cutting a fescue lawn at 4". Quite another to cut the same weed, or a weed with high surface tension leaves down to 3/4" or lower reel-cutting a bermuda lawn.

If I'm targeting noxious stuff with $200+/A chems during the summer I try to find a way to work around mowing. If I'm blanket spraying the cheap stuff in the spring or fall I just roll out and it is what it is can't say I've ever seen a significant difference spraying weeds in yards that looked like they'd been mowed that day.

 

We always have people cut before we spray. Always turns out better. I just did another one yesterday. Been doing it that way for yrs.

 

No plant biology expert here, but on some of the harder to control weeds it would makes sense, at least to me, that cutting then spraying quickly after would allow some easier uptake from the "open wound" as most grasses and weeds are somewhat hydrophilic otherwise you would not see water ball up on the leaf blade. Sure some is eventually taken up by the leaf system through stoma of the leaf and most of what we are using as carriers for the herbicide is water.

 

I would think the spray would be taken in much more from the surface of the leaf vs. the open wound or freshly cut top of the plant.
Plants will take in what ever is sprayed on it through epidermal layer of cells and pores called stoma.
These pores help it regulate gas and water exchanges within itself. If the plant is drought stressed the stoma will close to retain water. In times of rain or high humidity they will open.
I would guess these pores would close after mowing to conserve water, but might open up after a water based chemical is sprayed onto the leaf.
From what I read, these pores can open or close in about 30min.
An experiment is needed!

 

As an employee without a say in the matter I've been sent out many times to spray a lawn the day after it was cut. I've never noticed a negative effect on control.

I still hate it with a passion though, especially in early spring when lawns are still greening up. It is quite hard to see the tracks from your previous passes a lot of the time on a freshly cut lawn. :angry:

 

Myself, I don't think the stoma (stomata) allow any herbicide solution to enter the plant. The stomata are designed for gas exchange--carbon dioxide in and oxygen out. A such, they are mostly on the bottom of the leaf. Normally stomata are too small to permit water solutions to enter, unless the leaf is under water.

 

Correct you are RigglePLC but then why would I doubt your info LOL seriously you provide great info.

• Get access

• Weeds, Volume 7, Issue 2
• April 1959 , pp. 195-213
• This volume was published under a former title. See this journal's title history.

Foliar Penetration of Herbicides-Review and Present Status

• H. B. Currier (a1) and C. D. Dybing (a1)
• • https://doi.org/10.2307/4040221
  • Published online: 12 June 2017

Extract
Systemic herbicides applied to leaves must move from the leaf surface into uninjured phloem in sufficient quantity to be translocated throughout the plant. Contact herbicides must at least enter the leaf. Leaves of terrestrial plants are adapted to exchange of gases -water vapor, CO2, O2-but are not adapted to absorb foreign solutes in applied solutions and to translocate them systemically; insectivorous species and some water plants may be exceptions. Failure of herbicidal effectiveness often may be due to lack of penetration. However, selectivity towards herbicides is not clearly related to differential absorption (5, 82, 172, 176).

 

I just cut my lawn and sprayed some weeds Thursday. The weeds are curling up and dying off. Maybe one way is better than the other, but both ways work.

 

This discussion is becoming almost silly with anecdotes. For best results, follow the herbicide label. The manufacturer has done a lot of testing on a wide variety of weeds under a wide variety of conditions and to get the benefit of all that testing, just follow the label. If it says wait, wait. If it says don’t apply to stressed turf, wait. If it doesn’t say anything about mowing, don’t wait.

 

The more surface area of weed that sprayed, the more effective the treatment will be. If possible, I prefer to have customers hold off mowing in the Spring until I spray and then wait another couple days. The lawn will look ratty until the first spray but the results will be excellent. Under normal years, (this year was not one of them) weeds start growing well before the grass does and the amount of weed surface area is much larger.