Getting rid of whitetop/hoary cress

[KateParticipant]

After trying to identify this awful weed on my allotment plots in the past few years I’ve finally identified it as hoary cress. Have you had any experience of getting rid of it? The guy who I took the plot over from used weed killers every year but it always came back. Until this year I’ve dug it out every year but it returns (the tiniest bit of root means it returns and that’s without what happens if I don’t get it out before it seeds!)
So this year I’ve gone no dig. One plot has less of it and that one is where I have most of my soft fruit so I’ve just mulched heavily and am hoeing to try and keep it down (hoping it will weaken). The other plot is somewhat different in that it’s everywhere. I’ve created two no dig beds for salad and am hand pulling what comes through the thick mulch every other day. The rest of the bed I’ve put dpm over as a test to see if a year under cover might kill it off. Three months in and it’s still coming up but is very pale but certainly looks like it needs the year under cover. If it does I will do the same on the other half next year! Couldn’t cope with the thought of it all under cover for the year!
Any ideas on whether I’m on the right track? I’m under pressure from fellow allotmenteers to dig and spray!
Thanks Kate

[charlesModerator]

Hello Kate, I had not heard of hoary cress and just looked it up: what a monster!
Its growth habit sounds similar to couch grass and bindweed combined with a high seeding ability, oh dear.
I am sure that mulching offers you more hope than cultivation but suspect it will be difficult to eradicate among the soft fruit, though easier to keep on top of.
Yes I would keep polythene/membrane on for a whole year.
And its not fair of the other allotmenteers to complain of your approach which sounds highly conscientious, diligent and will be effective.
Do keep us posted and best of luck with it.

[bluebellParticipant]

Hi Kate
I think that there are always differences of opinion on allotments and I get equally annoyed at neighbours who spray because they cannot be bothered to do the work required.

This one will require consistent effort as the seed remains viable in the soil for a long time, however not digging should help by not bringing the seed to the surface. The more you weed and hoe the less impact it will have – it just takes a while to get to the point where you feel you are winning 🙂

[KateParticipant]

Thank you! Yes I’ll let you know. At least with this approach I feel I have a plan! After years of digging I think I’ve just been making it worse! Kate

[Don FoleyParticipant]

Hi Kate,

I had similar situation with new ground I took on about two years ago, though not Hoary Cress ( like Charles I have never heard of that) just lots and lots of perennial weeds. I covered the beds with about 4″ of Horse Manure and then covered them with DPC. It worked brilliantly and when I removed the DPC after 12 months I had the finest tilth I could wish for.
I think of this method as an in situ compost bin.

Don.

[Anonymous]

Its becoming a real problem now http://www.steamboattoday.com/news/2008/jun/23/whitetop_weed_invades_again/

[charlesModerator]

Thanks Arabella, it looks bad, and I am interested whether anybody has tried mulching.
It would need a large sheet of polythene, for example, because you need a bare area of no-man’s-land between any spreading weeds and bare soil for cropping.

[KateParticipant]

Hi
It’s me back to report how its gone! Well last year was an interesting one. After finally identifing the hoary cress, I decided than on one of my two plots to run an experiment to see if anything worked. Half the plot I mulched with cardboard and a thick layer of compost. The other half I left thick black plastic covering the whole area. The plastic was on for a year. The hoary cress was slower to get going under the mulch but then came back with avengence. I kept hand pulling every other day but as it spreads by root and seed this didn’t seem to help. If hoped this would weaken it….
The black plastic side it still came through but was v yellow and slower. The slightest chink of light and it grew out the sides!
By the end of the year I was pretty exhausted from it. I’ve got kids and work etc etc. The allotment committee by then were v concerned about it spreading. We found it on four plots (2 mine) and being heavy chemical users they did a lot of research on chemicals. Despite lots of discussions about the methods I was trying etc they really pushed to spray. I refused to keep growing there so moved to another plot. Looking back I could have pushed more but at the time I had a severe chest infection and was tired of the whole thing!
Since moving they’ve sprayed twice on three of the four plots. The fourth is still digging it out. However I removed the black plastic in autumn. That hoary cress dies back about Oct/Nov and reappears in early March. Everywhere they sprayed had died including grass except the hoary cress!! That is still coming through! Less admittedly but very much still there. Incidentally, where the black plastic was there is NO trace of the hoary cress! Obviously it might be slower that side and I’d certainly not was too disturb the soil as you’d likely bring the old seeds to the surface but I am now sure that had I covered the whole plot with plastic for a year, then practiced no dig them I could have got on top of it. The issue would be how to get rid of on the grass paths!! Certainly that would have been a challenge as my path was by the gate.
Hope that helps someone! Sorry for the long ramble.
Kate

[KateParticipant]

Apologies for the spelling mistakes! I just noted that the auto correct on the phone was working overtime!

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