As gardeners and outdoor enthusiasts, it may go against your better instincts to reach for the herbicide spray bottle, but occasionally an instance arises that calls for a little trigger-happy action. Perhaps the weeds have gotten out of control in your front lawn or you have decided to take out a patch of grass to make way for the Mrs’s flower beds. Whatever the reason, you might be undecided on which herbicide to use. If you have narrowed it down to Diquat Dibromide vs Glyphosate and can’t decide which is the right product for the job, read on. I’m going to compare the two below.
Diquat Dibromide vs Glyphosate: An Overview
Both herbicides are non-selective, meaning they will kill whatever plant material that they are applied to. The main difference is the way in which they kill the plants. Glyphosate is a systemic herbicide and Diquat Dibromide is a contact herbicide. This means that while Diquat Dibromide only kills plant tissue that it comes into direct contact with, Glyphosate will move through the plant from point of contact down to the roots.
Glyphosate takes longer to act but kills the whole plant, making it more effective on persistent or well-established weeds, and also means that they have less chance of reappearing. So, whether you are aiming to kill a patch of lawn or eliminate specific problem plants, Glyphosate would give you the most thorough and consistent results.
Comparing Diquat Dibromide vs Glyphosate in More Depth
Below I’m going to run through some of the main pros and cons of each of these products, so you can get a better understanding of which might be the best choice for what you’re trying to achieve with your lawn.
Pros of Diquat Dibromide
Less Likely to Kill Things You Don’t Want it to Kill
One of the pros that Diquat Dibromide has going for it is that it is a contact-type herbicide, so if small amounts of it drift onto non-target plants (it gets windy here where I live!) it won’t kill them. If you are the type of guy that doesn’t like to read the label carefully, there is less chance of you killing your entire lawn by mistake whilst trying to target specific weeds.
Not Temperature Sensitive
It is also not temperature sensitive, which means that you don’t have to wait for the perfect conditions before getting down to work. Other herbicides, such as Glyphosate, often don’t perform well in cold conditions. If the plants’ transport system has slowed down the herbicide won’t be distributed throughout its tissues. This could be a reason to use Diquat if you need to do lawn maintenance in the dead of winter or live in a cooler climate.
Rapid Localised Results
It kills only the part of the plant that it comes in contact with, and because it works so rapidly, it kills the parts responsible for translocation before it can move to other parts of the plants. This means that it can be used as a broadcasted herbicide to control weed emergence in established creeping grasses, such as Bermuda, while the grass is dormant.
Cons of Diquat Dibromide
It is Not Effective on Well Established Plants
Diquat is ineffective on perennials, hardy grasses, or some very well-established weeds. It will injure and may hinder the growth of perennials but likely not kill them outright. While this could be a positive factor if you plan to use herbicide as a desiccant, it will not help eliminate grasses with underground runners, such as Zoysia or Bermuda. It is, therefore, best suited to small annual weeds while they are still young, tender, and less than 6 inches in height. Weeds that have already grown greater than this will probably require repeated applications.
Pros of Glyphosate
Only One Application Necessary for Permanent Results
It may take longer to see results from Glyphosate because it takes time to move through the plant tissues and disrupt functioning. However, it kills all parts of the plant, including roots, and therefore has a better success rate with only one application. Using fewer applications makes it less expensive to use than herbicides that require repeated applications (like Diquat Dibromide often does).
It Is Inactive Once it Enters the Soil
Glyphosate has little to no soil residue and is not easily leached as it binds rapidly to clay particles. That means that once it enters the soil it won’t move through it to affect other neighboring plants.
Cons of Glyphosate
No Rectifying a Mistaken Application
You won’t be able to wash it off or trim away affected plant foliage after it comes into contact with plant matter, as once it enters the tissues the effects are irreversible. So beware, there is a greater chance that you can kill your whole lawn if you are not paying attention to the instructions.
Results Are Not Instantly Noticeable
Glyphosates do not have rapid results and take several days until you can notice it working. So if you need immediate results, it might not be the herbicide for the job.
Performance is Temperature Dependent
It works optimally at 65-85 degrees Fahrenheit so you should wait for a warm, sunny day if you want the best results.
Is Diquat Safer Than Glyphosate?
Perhaps your main concern isn’t product performance but rather the safety of your children or pets running around in your backyard and a more pressing question you are asking yourself is: is Diquat safer than Glyphosate?
Of the two, Glyphosate is safer. It works by disrupting a plant enzyme EPSP that is responsible for the production of amino acids in plants, and EPSP is not present in mammals. This means that it has low toxicity for people and animals. There is also no evidence of it being carcinogenic. It binds tightly to soil particles and is eventually broken down by soil bacteria, meaning it does not easily enter groundwater systems.
The use of surfactants added to it to increase herbicide efficacy is thought to be a contributing factor of its toxicity to aquatic organisms, and not the glyphosate on its own. Other products added to Glyphosate herbicides might also make them more toxic and irritable to people’s skin and eyes, even though Glyphosate itself doesn’t pass easily through the skin. PPE should be worn as a precaution when handling any chemical substance. If ingested it moves quickly through the body and leaves without being changed or absorbed.
Diquat Dibromide is an irritant to the skin, eyes, and respiratory tract, and moderately toxic to mammals if ingested. It is quickly absorbed by the body after ingestion and causes multiple organ cellular damage. It has the potential to affect the liver, kidney, stomach, and intestines, although it also doesn’t have any known carcinogenic factors.
Exposure to residue post-application is a concern with Diquat Dibromide and the correct use of personal protective equipment should always be used.
Can You Mix Diquat and Glyphosate?
I have seen some enthusiastic suggestions to mix Diquat Dibromide and Glyphosate. The theory is that whilst Glyphosate kills plant matter more thoroughly, it takes several days to work, and that by adding Diquat you can speed up the process.
In fact, it makes Glyphosate less effective than applying it on its own, and only appears to be working quicker. Diquat kills cells before Glyphosate can translocate through the plant, so it doesn’t reach other parts of the plant to do its job and there is more chance of weeds re-sprouting from their roots.
Although you may not get the satisfaction of seeing an immediate response after spraying the weeds, by using the two mixed together you are only using more herbicides in total, probably costing you more and with less effective results. So really you are cheating yourself for instant gratification and setting yourself up for long-term failure. Just because you can mix Diquat and Glyphosate together, doesn’t mean that you should.
Conclusion
When comparing Diquat Dibromide vs Glyphosate I would select Glyphosate as my preferred herbicide for spot treatments on non-selective weeds and grasses. It is relatively inexpensive when compared to other herbicides, only requires one application, is considered an environmentally friendly option, has low toxicity to humans, and kills just about anything it touches that is green and grows.
Just remember that none of these products should be used as a blanket treatment on your lawn unless you intend to kill that too. There is nothing worse than relaxing on your lawn chair in summer, a beer in your hand, and feeling your toes rub against dead grass. No one has ever sung a country song about that particular scenario.
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