Resolva weed killer: which one have you actually bought?
Resolva is not a formula, it is a badge. The register carries 54 Resolva rows across four completely different chemistries, Westland holds not one of the authorisations, and three products share the name Path & Drive. Here is every Resolva decoded, with the number that tells you what is really in the bottle.
By The Weed GuyLast updated
The short version
The word Resolva tells you nothing about what is in the bottle. Four unrelated chemistries wear the badge: glyphosate and the lawn hormones, which are systemic and reach the root, and pelargonic acid and acetic acid, which burn what they touch and cannot. Three products are called Path & Drive, two are called 24h, and Xtra, Xtra Fast and Xtra Tough are three different chemicals. Turn the pack over, find the five-digit MAPP number, and buy that instead of the brand.
Every Resolva, decoded
Read off HSE's amateur pesticides register on 14 August 2026, product by product. Westland's own website names an active substance on only a handful of pages and a registration number on almost none, and no retailer listing I found states either, so this comes from the register rather than from anybody's marketing.
| Name on the register | Active substance | Strength | MAPP number |
|---|---|---|---|
| Resolva Weedkiller 24h RTU | Glyphosate | 8.39 g/L | 18921 |
| Resolva 24h Weedkiller Concentrate | Pelargonic acid + maleic hydrazide | 186.7 + 30 g/L | 21895 |
| Resolva Xpress 24h | Pelargonic acid | 31.02 g/L | 19538 |
| Resolva Xtra Tough | Glyphosate | 8.39 g/L | 17648 |
| Resolva Xtra Fast Weedkiller | Pelargonic acid | 31.02 g/L | 20063 |
| Resolva Xtra Fast Concentrate | Pelargonic acid | 186.7 g/L | 20062 |
| Resolva Xtra Ready To Use Weedkiller | Mecoprop-P + dicamba | 3.75 + 0.468 g/L | 19317 |
| Resolva Xtra Ready To Use | 2,4-D, dicamba, MCPA, mecoprop-P | Four-way mix | 19319 |
| Resolva Path & Drive | Acetic acid | 60 g/L | 19199 |
| Resolva Path & Drive Weedkiller RTU | Pelargonic acid | 31.02 g/L | 21365 |
| Resolva Path & Drive Concentrate | Pelargonic acid | 186.7 g/L | 21852 |
| Resolva Fast Weedkiller | Acetic acid | 60 g/L | 19308 |
| Resolva Lawn Weedkiller Extra RTU | Mecoprop-P + dicamba | 3.75 + 0.468 g/L | 16863 |
| Resolva Lawn Weedkiller Extra Concentrate | Mecoprop-P + dicamba | 37.5 + 4.675 g/L | 16848 |
| Resolva Pro Weedkiller (sold as Pro Xtra Tough RTU) | Glyphosate | 8.39 g/L | 18143 |
| Resolva Pro Weedkiller Liquid Sachets | Glyphosate | 72 g/L | 18521 |
| Resolva Pro Weedkiller Concentrate | Glyphosate | 151.4 g/L | 18934 |
| Resolva Pro Weedkiller Super Concentrate | Glyphosate | 360 g/L | 18936 |
| Resolva Super Strength Xtra Tough Concentrated | Glyphosate | 360 g/L | 15853 |
| Resolva Weed And Root | Glyphosate | 90 g/L | 21121 |
Twenty of the products people actually meet, out of 54 register rows covering 47 distinct Resolva products in total. The strength column runs from 0.468 grams a litre to 360, which is a spread of nearly eight hundredfold inside one brand name. There is also a moss line, a slug killer, a fungicide and two insecticides wearing the same badge.
Westland does not hold a single Resolva authorisation
This is the finding that explains all the others, and I did not expect it. Every one of the 54 Resolva rows on the register lists Westland Horticulture as the Marketing Company. Not one lists Westland as the Authorisation Holder.
Seven other companies hold the approvals. Syngenta holds every glyphosate Resolva. W. Neudorff holds most of the pelargonic acid ones. Compo holds the Zero and Mosskiller Ultra lines. Sipcam Home and Garden holds both acetic acid products. Hygeia Chemicals and Arysta LifeScience hold different halves of the lawn range. Barclay Chemicals holds Resolva Weed And Root.
So Resolva is a badge applied to other manufacturers' formulations, and that is precisely why the chemistry underneath it is so inconsistent. A brand that develops its own products tends to have one house approach. A brand assembled by licensing other people's approvals ends up with four unrelated chemistries and a naming scheme that has to stretch across all of them. Own-brand provenance works the same way across the whole category, which is set out on where to buy weed killer in the UK.
Xtra, Xtra Fast and Xtra Tough are three different chemicals
If you take one thing from this page, take this one, because the three names sit together on a shelf and reaching for the wrong one can kill the thing you were trying to keep.
- Resolva Xtra is a selective lawn herbicide. Mecoprop-P and dicamba, hormone chemistry, designed to leave grass alive.
- Resolva Xtra Fast is 31.02 g/L pelargonic acid. Non-selective, contact only, kills the grass and never reaches a root.
- Resolva Xtra Tough is 8.39 g/L glyphosate. Non-selective and systemic, so it kills the grass and does reach the root.
Three products, one prefix, three unrelated modes of action, and two of the three will leave a dead patch on a lawn the shape of your spray pattern.
It gets worse one level down. "Resolva Xtra Concentrate" under MAPP 19306 is a four-way hormone mix of 2,4-D, dicamba, MCPA and mecoprop-P, held by Arysta LifeScience. "Resolva Xtra Concentrate Weedkiller" under MAPP 19313 is a two-way mix of mecoprop-P and dicamba, held by Hygeia Chemicals. Different companies, different formulations, and the entire difference between the two names on the shelf is the word Weedkiller. The same trick repeats on the ready-to-use pair, 19319 and 19317.
Path & Drive is three products, and 24h is two
Two names in the range resolve to more than one product each, and in both cases the products involved work by different mechanisms.
Path & Drive. Three live authorisations use it. MAPP 19199 is 60 g/L acetic acid, held by Sipcam Home and Garden. MAPP 21365 is a trigger bottle, pelargonic acid at 31.02 g/L, held by W. Neudorff. MAPP 21852 is a concentrate, the same acid at 186.7 g/L. Two chemistries, a sixfold strength range, one name. There was a fourth, MAPP 21260, but HSE's withdrawal notice of 4 September 2025 confirms it was superseded by 21365 rather than being a separate product, which is the kind of thing you only learn by reading the notices.
24h. Resolva Weedkiller 24h RTU under MAPP 18921 is 8.39 g/L glyphosate, held by Syngenta. Resolva 24h Weedkiller Concentrate under MAPP 21895 is 186.7 g/L pelargonic acid plus 30 g/L maleic hydrazide, held by Neudorff. Both are currently authorised. One is systemic and one is contact, and the name they share is a claim about how fast you will see something rather than about what is in the bottle.
Then there is Resolva Xpress 24h under MAPP 19538, another 31.02 g/L pelargonic acid product, which Westland has retired from its own website while the authorisation runs to June 2029. I still saw the bottle listed at Wickes at £17 for three litres on 14 August 2026, sitting alongside Resolva 24 Hour at £6.50 a litre. Nothing on either listing hints that they are unrelated products. The mechanism they differ on is the one this whole site turns on, and it is set out in what actually kills weeds for good.
How long does Resolva take to work?
Between one hour and four weeks, and which end you land on depends on the chemistry rather than the brand. Every figure below is Westland's own published wording for its own products, read on 14 August 2026.
| Chemistry | What you see, and when | Rain window | Root? |
|---|---|---|---|
| Acetic acid, 60 g/L | Westland claims visible results in 1 hour, and says weeds and moss should start dying within the hour if they are actively growing. | Do not apply if rain is expected within 6 hours. | No |
| Pelargonic acid, 31.02 to 186.7 g/L | Fast visible results in just 3 hours, in Westland's own words. Path and Drive is sold on targeting weeds in 3 hours and working within one day. | Rain within 12 hours may impair performance. | No |
| Glyphosate, 8.39 to 360 g/L | Visible effects may be seen after 24 hours, then a few days to a fortnight of yellowing, and up to 4 weeks for tougher weeds. | Rain within 6 hours may reduce effectiveness, on the concentrate and sachet pages. The trigger bottle gives no hour figure. | Yes |
| Mecoprop-P and dicamba (the lawn line) | Twisting and distortion in the leaves and stem after a couple of weeks, then the weed dies over the following weeks. | Control may be reduced if rain falls within 24 hours. | Yes |
Read that table down the speed column and then down the root column, because the two run in opposite directions. The fastest Resolva on the shelf is the one least likely to have killed anything, and the slowest is the one doing the work. If a drive browned off inside an hour and was green again three weeks later, nothing went wrong with your spraying. You bought a contact herbicide.
Two practical notes the marketing does not lead with. The acid bottles carry a seasonal lockout: Westland's own instruction is that the product must not be applied between the 18th of September and the 1st of April. And the rain windows are not interchangeable, so a 12-hour dry spell is a genuinely different planning problem to a 6-hour one. The broader version of that judgement is on whether you can spray weeds in the rain, and how long the spray takes to dry is a third clock again.
Resolva lawn weed killer, and why it shares a name with something opposite
The lawn line is the one part of the range where the chemistry is straightforward, and the naming still manages to be a trap.
Resolva Lawn Weedkiller Extra is a hormone herbicide: mecoprop-P and dicamba. The concentrate under MAPP 16848 is 37.5 g/L mecoprop-P plus 4.675 g/L dicamba, and the ready-to-use under MAPP 16863 is a tenth of that, 3.75 plus 0.468. Both authorisations are held by Hygeia Chemicals rather than Westland. Hormone chemistry is what lets a product take dandelions and clover out of turf without killing the turf, and it is a genuinely different job to everything else on this page.
Here is the trap. Resolva Xtra Concentrate Weedkiller under MAPP 19313 and Resolva Xtra Ready To Use Weedkiller under 19317 are the same two concentrations of the same two actives, held by the same company. It is the lawn product under a second name. Meanwhile Resolva Xtra Fast, one word away on the shelf, is a non-selective contact acid that will take the lawn with the weed.
Lawn treatments are outside what this website covers, so there is no recommendation here and no rate advice. The reason it belongs on this page at all is the same reason as everything else: the brand name spans two opposite regulatory jobs, so "I use Resolva" describes almost nothing about what is going on in your garden.
What I found wrong on the manufacturer's own website
Checking every product in the table against the register turned up a set of straight contradictions on Westland's own pages. I am reporting them rather than repeating them, because a reader deciding what to buy needs to know which document to trust.
- Six live pages still name diquat. Three of them quantify it, giving glyphosate at 8.3 g/L alongside diquat at 0.3 g/L. Diquat's GB approval ended in 2020, and HSE lists glyphosate as the only active substance in those products. A currently sold amateur product cannot legally contain it.
- The 360 g/L page serves the 151 g/L safety sheet. Resolva Pro Xtra Tough Super Concentrate states 360 g/L glyphosate in its own safety box, and its download button hands you the data sheet for a different registration at 151.04 g/L.
- A tenfold units error in a safety data sheet. The Resolva Fast sheet describes the product as containing 60% acetic acid in one section and 6% by weight in its own ingredient table two lines below. The register figure, 60 grams per litre, is the second one. Sixty per cent acetic acid is an industrial corrosive, not a garden bottle.
- Root-kill claims on products that cannot do it. A systemic, kills-the-entire-root paragraph appears on acid bottles that are contact only, including one acetic acid page that calls the product selective in one line and confirms in its own FAQ that it kills grasses as well.
The rebuttal comes from Westland itself. The FAQ on its Resolva Moss Killer page says plainly that the active product does not kill the weed down to the root. That product is pelargonic acid, the same active as Xtra Fast, Xpress and the Path and Drive ready-to-use, so the honest sentence and the misleading ones are describing the same chemical.
One more thing worth knowing before you search. The website that ranks near the top for the brand name is not Westland's at all. It is a third-party affiliate site, and it describes Resolva Xpress 24H as containing ferrous sulphate. The register says pelargonic acid. Ferrous sulphate is an iron salt used on moss and lawns, and there is none of it in that bottle.
What to actually read on a Resolva pack
Every word on the front of a Resolva bottle is marketing, and I mean that literally rather than as a complaint. Xtra, Fast, Xpress, Pro, Tough, Super Strength, 24h and Zero are not regulated terms and none of them has to correspond to anything. The Pro line alone runs at 8.39, 72, 151.4 and 360 grams of glyphosate a litre, a 43-fold spread under one sub-brand, and its strongest member is the one whose own page gives the rate as 16ml per litre of water for annual weeds and 24ml for perennials, covering 40 square metres a litre either way.
So work from the back of the pack. The MAPP number is five digits, legally required on the pack, and the only identifier that resolves to exactly one formulation. Type it into HSE's free garden pesticides register and the entry that comes back settles what is in the bottle, how much of it, and who holds the approval. The active substance then tells you the mechanism: glyphosate and the mecoprop-P and dicamba pair are systemic, pelargonic acid and acetic acid are contact only, whatever the pack says.
One warning about that lookup, specific to this brand. The register name and the shelf name often differ. MAPP 18143 is registered as "Resolva Pro Weedkiller" and sold as "Resolva Pro Xtra Tough Weedkiller Ready to Use", so searching the register by the name printed on the bottle can return nothing at all. Search by the number, not the words. That 360 g/L ceiling and who may legally spray what above it is argued properly on the strongest weed killer resource rather than repeated here.
The acetic acid Resolvas have an end date on them
If you are choosing between the acid bottles, this is worth factoring in, and it is worth stating precisely because the rumour version of it is wrong.
There is a dated timetable hanging over MAPP 19199 and MAPP 19308, the two 60 g/L acetic acid Resolvas, and it arrives via HSE amendment notice 20250596 of 1 April 2025. That notice puts an end date on roughly thirty amateur acetic acid product authorisations. The authorisation itself stops on 30 November 2027. Shops may sell what they already hold until 31 May 2028. Anything left in a shed may be used up or disposed of until 31 May 2029. The reason printed on the notice is Commission Implementing Regulation 2023/1446.
What that is not is a ban on acetic acid. The active substance remains approved for use in Great Britain, and the notice ends specific product authorisations rather than the chemistry. It does not touch the pelargonic acid Resolvas, the glyphosate ones or the lawn line. So it does not make a bottle you already own unsafe to use. It does mean that one of the two chemistries sharing the Path and Drive name is on a timetable and the other is not, which is one more reason the number on the back matters more than the words on the front.
What I would buy over a Resolva bottle
The Resolva ready-to-use packs are convenient and priced for it. Past a few square metres, the same job done from concentrate is a different order of cost entirely.
What I’d use
Glyphosate concentrate, 360 g/L
Gallup Home & Garden Glyphosate Weedkiller (1 litre)
The one Gallup a homeowner can legally buy and use: a 1 litre glyphosate concentrate at 360 g/L, approved for home and garden use under MAPP 17672.
It is the same active, the same 360 g/L loading and the same isopropylamine salt as the professional Gallup XL, and its single label rate of 24 ml per litre of water is exactly the rate the professional labels reserve for perennial broad-leaved weeds. The difference between the two bottles is the authorisation printed on them, not the chemistry inside, and this is the side of that line you are allowed to stand on.
- Active ingredient
- Glyphosate, 360 g/L, as the isopropylamine salt
- Formulation
- Soluble concentrate you dilute yourself
- Approval
- MAPP 17672, labelled for use only as a home and garden weedkiller
- Mixing rate
- 24 ml per 1 litre of water, per the label
- Coverage
- 40 sq m per litre of made-up spray, so roughly 1,667 sq m per bottle
- Rainfast
- Rain within 6 hours may reduce effectiveness, per the label
- Size
- 1 litre of concentrate
Watch out for
- No measuring cap in the bottle. Check a cup arrives, or the dose is guesswork.
- One re-treatment a season, and it takes four weeks. Do not go again early.
- Not for lawns. It is non-selective and takes the grass too.
- Resellers dominate the listing, so check the label that arrives is Barclay.
- "Super strength" is keyword stacking. It is 360 g/L, same as professional Gallup XL.
That’s an affiliate link: buy through it and I earn a small commission at no extra cost to you. It doesn’t change what I recommend or what I say is wrong with it. More on how that works in the affiliate disclosure.
No brand pays for a mention here, and nothing on this page is a paid-for opinion. The card above is an affiliate link, so I earn a commission if you buy through it, at no extra cost to you. It buys no product a kinder write-up, which is why the watch-outs sit on the same card as the reasons to buy.
About this resource
I'm The Weed Guy, one bloke who is qualified to use professional weedkiller. Every MAPP number, active substance, concentration and authorisation holder on this page was read off HSE's amateur home garden pesticides register on 14 August 2026, one product detail page at a time, and every timing figure, rain window and application rate came from Westland's own product pages and safety data sheets on the same day. Anyone can repeat both lookups, and the point of the page is that you should.
Anything I could not stand up is absent rather than smoothed over. Westland publishes no prices and sells nothing direct, so the only money quoted here is two dated August 2026 shop snapshots. The Super Concentrate page states no annual maximum, so this page states none. The 24h trigger bottle gives no rain figure, so the 6-hour window is attributed to the products that actually print it. I could not tell which registration sits inside the Path and Drive pack any given shop is selling, which is the exact problem this page is about. And none of this comes from me running the products against each other; there is no such test behind it.
Straight disclosure: Westland does not sponsor this website, nobody paid for a word of it, and this page carries no product links whatsoever. That independence is the only thing that makes a page about one brand worth reading. It is why the diquat contradiction and the mismatched safety sheet get written up instead of quietly dropped, and why every Resolva above is described by its register entry rather than by its packaging. The full position on how this site earns anything is on the affiliate disclosure page.
Common questions
How long does Resolva weed killer take to work?
Between one hour and four weeks, depending entirely which Resolva you bought. Westland puts the acetic acid bottles at visible results in 1 hour, the pelargonic acid ones at fast visible results in just 3 hours, and the glyphosate ones at visible effects after 24 hours with up to 4 weeks for tougher weeds. The lawn products are slowest of all: a couple of weeks before the leaves even start twisting. And the ranking inverts what you want, because the two fastest chemistries are contact-only and never reach a root, while the slowest two are the systemic ones that actually kill the plant.
What is the difference between Resolva 24H and Resolva Xpress 24h?
They share no active ingredient. Resolva Weedkiller 24h RTU, MAPP 18921, is 8.39 g/L glyphosate and its authorisation is held by Syngenta. Resolva Xpress 24h, MAPP 19538, is 31.02 g/L pelargonic acid and its authorisation is held by W. Neudorff. Glyphosate is systemic, so the plant carries it into the root. Pelargonic acid is a fatty acid: it wrecks the cells it physically touches, and the plant never moves it anywhere. Westland has since retired the Xpress line from its website, though the authorisation runs to June 2029 and I saw the bottle on a Wickes listing in August 2026, so it is still out there.
Does Resolva weed killer contain glyphosate?
Some do and most do not. The register carries 54 Resolva rows covering 47 distinct products, and only a minority are glyphosate: the 24h and Xtra Tough trigger bottles at 8.39 g/L, the Pro line at 72, 151.4 and 360 g/L, Super Strength Xtra Tough at 360 g/L and Weed And Root at 90 g/L. The rest of the range runs on pelargonic acid, acetic acid, or the mecoprop-P and dicamba hormone pair used in the lawn products. Nothing on the front of a pack sorts them into those groups.
Who actually makes Resolva weed killer?
Not Westland, which is the answer almost nobody expects. Westland Horticulture is listed as the Marketing Company on all 54 Resolva rows on the HSE register and as the Authorisation Holder on none of them. The approvals belong to seven other companies: Syngenta holds the glyphosate products, W. Neudorff holds most of the pelargonic acid ones, Compo holds the Zero and Mosskiller Ultra lines, Sipcam holds the acetic acid ones, Hygeia and Arysta LifeScience hold different halves of the lawn range, and Barclay Chemicals holds Weed And Root. Resolva is a badge applied to other manufacturers' formulations, which is exactly why the chemistry underneath it is so inconsistent.
Which Resolva Path & Drive have I got?
You cannot tell from the name, because three live authorisations use it and they do not agree. MAPP 19199 is 60 g/L acetic acid, held by Sipcam Home and Garden. MAPP 21365 is a ready-to-use at 31.02 g/L pelargonic acid, held by W. Neudorff. MAPP 21852 is a concentrate at 186.7 g/L pelargonic acid. So that is two different chemistries and a sixfold strength range under three words on the front of a bottle. Turn the pack over, find the five-digit MAPP number, and look it up on HSE's free garden pesticides register.
Does Resolva kill weeds to the root?
The glyphosate ones do, and so does the lawn line. The acid ones cannot, and Westland says so itself in one place: the FAQ on its own Resolva Moss Killer page states that the active product does not kill the weed down to the root. That product is pelargonic acid, the same active as Xtra Fast, Xpress and the Path and Drive ready-to-use, so the admission applies to all of them. Several other Resolva pages nonetheless carry a kills weeds and roots line on contact-only products, which is the contradiction to watch for.
What is Resolva lawn weed killer, and is it the same as Resolva Xtra?
It is a selective lawn herbicide, and yes, it is the same formulation as one of the Resolva Xtra products. Resolva Lawn Weedkiller Extra comes as a concentrate under MAPP 16848 at 37.5 g/L mecoprop-P plus 4.675 g/L dicamba, and as a ready-to-use under MAPP 16863 at 3.75 plus 0.468 g/L. Resolva Xtra Concentrate Weedkiller (19313) and Resolva Xtra Ready To Use Weedkiller (19317) are the identical pair of concentrations under different names, all four held by Hygeia Chemicals. Those are hormone herbicides that leave grass standing, which is a different job to everything else in the range.
Does Resolva 24H contain diquat?
The HSE register says no, and the register is the document that has to be true. MAPP 18921 lists one active substance, glyphosate at 8.39 g/L. Six pages on Westland's own website still name diquat, and three of them quantify it as 0.3 g/L alongside the glyphosate, but diquat's GB approval ended in 2020 so a currently sold amateur product cannot legally contain it. I am reporting the discrepancy rather than resolving it, because I cannot see from outside which document is stale. Read the pack in your hand and check its MAPP number, which settles it in thirty seconds.
What is the strongest Resolva weed killer?
Resolva Pro Weedkiller Super Concentrate at 360 g/L glyphosate under MAPP 18936, with Resolva Super Strength Xtra Tough Concentrated at the same 360 g/L under MAPP 15853. Both sit on the amateur register, so no certificate is involved. Its own page gives the rate as 16ml per litre of water for annual weeds and grasses and 24ml per litre for perennial and other difficult broadleaved weeds, either one covering 40 square metres per litre of made-up spray. That is roughly 43 times the glyphosate concentration of the 24h trigger bottle, out of the same brand.
Can I use Resolva weed killer on my lawn?
Only the lawn line, and getting that wrong is expensive. Resolva Lawn Weedkiller Extra and Resolva Xtra are selective hormone products designed to leave grass standing. Everything else carrying the Resolva name is non-selective and will kill the grass along with the weed, which means a Resolva Xtra Fast bottle and a Resolva Xtra bottle do opposite things on a lawn despite sharing a word. Check for mecoprop-P and dicamba on the pack before anything goes near turf.
Is Resolva being banned?
No, and the timetable that does exist is narrower than the rumour. One chemistry in the range is affected: the 60 g/L acetic acid products, MAPP 19199 and MAPP 19308. HSE amendment notice 20250596 of 1 April 2025 puts an end date on roughly thirty amateur acetic acid product authorisations, with the authorisation stopping on 30 November 2027, retail stock sellable to 31 May 2028 and anything already bought usable to 31 May 2029. That is specific products losing their approval. Acetic acid itself remains an approved active substance in Great Britain, and no pelargonic acid, glyphosate or lawn Resolva is touched by the notice.
Is Resolva weed killer any good?
The chemistry is fine and the naming is the problem, which is a different criticism to the one people usually make. The 360 g/L glyphosate concentrates are as strong as the home garden register goes. The lawn products are an ordinary mecoprop-P and dicamba pair that does what it says. The acid bottles are competent contact herbicides being bought by people who wanted a root kill. What lets the brand down is that none of those packs tells you which of the four chemistries you are holding, so the honest verdict is to judge the registration rather than the name.