If you’re concerned about crabgrass control and begin scouring the internet for reliable treatment options, you’ll likely come across two effective choices: prodiamine and dithiopyr. These are generic names–not brands–but various products will list one or the other as an active ingredient for crabgrass and broadleaf weed control for turf grasses. But what’s the difference between these weed control solutions, and which is better for your lawn? Here, we’ll explore the pros and cons of prodiamine vs dithiopyr for weed control and crabgrass control in residential lawns.
Keep in mind what pre- and post-emergent mean when it comes to killing weeds. In spite of both types, the weed seed germinates. Pre-emergent herbicides prevent the seedling from emerging from the soil. Post emergents kill the weed after it penetrates the soil surface. To stop the seedling prior to emerging in your lawn, opt for a pre-emergent that stops the weed right after the seed germinates and emerges from the seed.
First, keep in mind that prodiamine is a pre-emergence herbicide. Pre-emergents don’t kill weed seeds; they kill the weed seedling as soon as it begins to sprout from its seed but before it emerges from the soil surface. Post-emergent herbicides like dithiopyr kill weeds after they emerge from the soil surface. However, dithiopyr works as both a pre-emergent herbicide and post emergent herbicide on your ground.
The benefits of prodiamine include:
- Long lasting: prodiamine can provide a pre-emergent chemical layer of protection for up to nine months.
- Inexpensive: prodiamine, especially in generic form, tends to be less expensive than dithiopyr.
- Best for early applications: if you prefer to control broadleaf weeds early / crabgrass early in the growing season, pre-emergents like prodiamine are highly effective.
- Highly effective: prodiamine works great for killing crabgrass as well as other weeds.
Not all lawn care experts prefer the use of prodiamine. Here’s why:
- Requires fast watering: prodiamine needs to be watered quickly after its application. It will lose substantial efficacy if it’s not watered within 14 days of its application.
- Not best for broadleaf weed control: although used as a control for crabgrass, prodiamine is not regarded as effective for killing broadleaf weeds as other control methods.
- Photodegradation: prodiamine breaks down with sunlight. Consequently, it may require two applications. (on the other hand, if you intend to aerate and overseed your soil later in the season, you can lower your mowing cut to allow more sunlight to penetrate the soil and inhibit this pre-emergent herbicide.
- Messy: prodiamine in liquid spray form is messy and yellow. However, even if you choose products made with granules, the watering needs of the product can still leave your sidewalks, pavers, ground, or rocks with yellow staining.
Dithiopyr Pros (known by the brand name Dimension)
Dithopyr, Dimension, works as both a pre-emergent and early post-emergent herbicide, which makes it a versatile option for killing a tough weed like crabgrass. It’s also known to kill a wide range of turf weeds–about 45.
Here are the pros of using dithiopyr for lawn weed control:
- Efficacy: in the battle between prodiamine vs dithiopyr, dithiopyr is a more effective method of preventing weeds in the grass.
- Post-emergent capabilities: unlike prodiamine, dithiopyr can kill young weed seedlings after they emerge from the soil. (If using Dimension at max rates with a non-ionic surfactant). It has a wider window for use for this reason.
- Later turf application time: you can use dithiopyr later in the season (it has a longer window for potential use), which makes it a great second or third option for your split application.
Cons of Dithiopyr (known by the brand name Dimension)
Not all gardeners love dithiopyr for their grass: here’s why:
- Root pruner of grass: be sure your grass roots are well established before applying dithiopyr.
- Expense: dithiopyr will cost you more than prodiamine to treat your grass. Consider your lawn size when making your decision.
- Reduce efficacy time: prodiamine lasts longer than dithiopyr, which will only remain effective for 3-4 months.
- Larger dose: you’ll need more dithiopyr than prodiamine to kill crabgrass. Again, lawn size may affect your choice here.
- Vulnerable: dithiopyr is more vulnerable to water and heat than prodiamine. Heavy rainfall can reduce its efficacy.
Pre-emergents, post-emergence control–the pros and cons of these two quality lawn weed control measures may still leave you uncertain about the one to choose for your turf or grass type. When in doubt, research your grass type to see what lawn care experts have to say about their use on cool-season grasses, warm-season grasses, and your specific grass type. One may be better than the other for your type of grass. Be sure to wear safety equipment no matter what type of weed-controlling product you choose for your grass type.
Also, remember that timing is important. If you need a wider window of use for applying a crabgrass preventer, dithiopyr may be the better choice. On the other hand, if you want your product to control weed growth for a longer window of time, opt for prodiamine. Be sure to read the label of any product you choose so you can apply the full rate of the product’s active ingredient safely and at the right time.
Bottom line: I always apply a Prodiamine product (0-0-7 or 19-0-7 granular) in the early spring (late March/early April in Massachusetts) before the soil temperatures hit 55 degrees. The next round is Dithiopry 6-8 weeks later. I like the 21-0-10 with a 0.25% Dimension from The Andersons.
Prodiamine vs Dithiopyr FAQs
Is dithiopyr a good pre-emergent herbicide for a lawn?
Yes, dithiopyr is an effective pre-emergent. It also has post-emergence lawn weed-killing properties. Grass type may play a role, however. Remember that some weed killers only target certain weeds. Be sure that you use an herbicide that’s ideal for your grass type (i.e. Kentucky bluegrass, fescues, Greensboro NC grass type) and for the weeds in question.
Can you mix prodiamine and dithiopyr on your lawn?
You can apply your first application with prodiamine and then use dithiopyr as your second or third application 6-8 weeks later. If your lawn size is large, gardeners often prefer a first prodiamine app because it’s cheaper.