Will Clethodim Kill Sunflowers? (Explained)

Will clethodim kill sunflowers header

Herbicides are great for controlling unwanted plants and vegetation, but there is often a nagging doubt about the damage they could do to the plants you DO want to grow.

That is why it is always best to err on the side of caution before tackling weeds or grasses that might be growing in your garden.

In this article let me answer the question, ‘will clethodim kill my sunflowers?’ and explain a bit more about the substance and how to use it.

So let’s get started.

Will Clethodim Kill Sunflowers?

No clethodim will not kill sunflowers. It kills grasses only and can be used in and around sunflowers without any cause for concern. The active ingredient in clethodim is absorbed by grass to kill it from within, and it works well on both annual and perennial grasses.


What is Clethodim?


Clethodim is a postemergence herbicide that is designed specifically to control weedy grasses and certain invasive species. It is often sold as Arrow 2EC or Clethodim 2EC.

Postemergence herbicides are applied when weeds or grasses have already appeared, whereas preemergence herbicides are applied before weeds or grasses even germinate, stopping them in their tracks before they have a chance to rear their ugly heads.

Clethodim is very commonly used and is considered one of the better herbicides for both annual and perennial grass control.

In fact, clethodim is the only graminicide (a herbicide with the intent of controlling weedy grasses) that controls annual bluegrass and it is effective on other grasses such as foxtail, crabgrass, ryegrass and Japanese stiltgrass. It is also very handy for controlling bermudagrass and fescues.

In terms of its safety, it is classed as moderately toxic to aquatic plants, fish, birds, honey bees and earthworms, but less so to aquatic invertebrates and algae. It is also categorized as moderately toxic to mammals.

Aside from some cases of mild skin irritation, no serious health effects have been associated with it.


Is Clethodim Dangerous to Sunflowers?


Sunflowers with blue sky behind

In short, no it isn’t.

Clethodim kills grasses only, meaning you can spray away around your sunflower, no matter what variety, and you will be fine.

It kills the grass from within, so when it comes to broadleaf plots it is a great option as it won’t affect them.


How Do You Use Clethodim?


The first thing any good gardener does when they buy a new product is to read the label right?

Ok, I have to admit I don’t always!

But with clethodim you should, as it is important to use it correctly.

For clethodim to work, it needs to be mixed with a ‘surfactant’.

A surfactant is simply a chemical additive mixed with herbicides to increase its effectiveness. The surfactant bonds the herbicide to the plant you are spraying it on and allows it to be better absorbed.

If you spray clethodim without adding the required surfactant, it won’t work. Dish soap and crop oil can be used as a surfactant.

Like pretty much all herbicides, timing is everything when it comes to using clethodim. It is best applied when the grass is under 6 inches, otherwise a second application further down the line may be necessary.

Clethodim usually takes between 10 and 30 days to kill grass completely, so some patience is necessary.


How Much Clethodim Should You Use?


Unfortunately, there is no real answer to this, as it can vary depending upon the product (clethodim is sold under many different trade names), what type of grass you are trying to kill and how far it has grown.

When I was doing some background research on this article I did make notes from various sources on their usage of clethodim. 

So below is some first-hand feedback on the substance and what people found to be a good rate to use:

  • “For a couple of acres of sunflowers with lots of grass coming in: Clethodim 2EC, 12oz rate with some crop oil.”
  • “For volunteer wheat and pigeon grass, 6oz/A is plenty. The higher rates are for quackgrass or other perennial grasses like you would see in CRP breakout.”
  • “Last week I sprayed my clover, brassicas and some alfalfa. I have a four-gallon backpack sprayer and used 2oz to four gallons, with two cups of crop oil mixed in.”
  • “I check four clethodim labels, and they all sing from the same hymn sheet for clover, 6-16oz per acre, not to exceed 16oz per year, a 5 to 40-gallon sprayer and a quart of crop oil”
  • “I have a 14-gallon sprayer, and last year I used 8oz of cleth and a quart of crop oil for a full tank. I sprayed the whole tank evenly on my acre plots and used half of it on my half-acre plots and it worked well.”
  • “I use 8-16oz of cleth, with 6oz crop oil in 15 gallons of water. That does around 2 acres for me, and always works well”.
  • “I will tell you that 10oz/acre of Clethodim with 1 quart/acre of crop oil, will do a great job. It is always a good idea to do a dry run though. Just have water in your tank over a measured area and work out how many gallons per acre you are applying.

Other Herbicides


Sunflower field in Spain

Can You Spray Raptor On Sunflowers?

Raptor can be used as a postemergence herbicide in Clearfield sunflower varieties only. Raptor is an imidazolinone herbicide and shouldn’t be used on sunflower varieties that are not tolerant to imidazolinone herbicides.

Can You Spray Roundup On Sunflowers?

If the sunflowers are mature, then spraying Roundup on them should not do them any damage.

Can You Spray Atrazine On Sunflowers?

Sunflowers are not very tolerant of atrazine, and it can lead to stunting of seedlings, yellowing of leaves and browning or leaf tip burning. In the worst cases, the sunflower may die.

Can You Spray 2, 4-D On Sunflowers?

2,4-D has been proven to be harmful to sunflowers, with damage from 2,4-D drift reported as part of a long-term study in Canada.

Can You Spray Cadre On Sunflowers?

Cadre can be used on Clearfield sunflowers only, at a 3oz rate.

Can You Spray Treflan On Sunflowers?

Yes Treflan is safe to use on and around sunflowers along with a number of other plants and vegetables.


Final Thoughts


Clethodim is a very popular herbicide, and when it comes to usage in or around sunflowers, then it is for a good reason.

It won’t kill your sunflowers but will do a good job of killing any weedy grasses that may be growing around them and vying for valuable soil nutrients and moisture.

You will need to work out the amount you need to use, and make sure you mix it with a surfactant.

Then have a bit of patience and voila, in a month or so the offending grasses should be killed off.

Good luck!

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