With grasses I would think the idea would be the younger the better so they have not had time to develop a large root base - which takes more vinegar. In dealing with Whitetop, the extension agent said if one is going to spray, they need to time the spraying to when the plant is winding down for the season and is taking food stores back down to the roots . Otherwise all you would be doing was burning the tops. Yes that could serve to set the plant back and enough of it might kill the plant, but it wouldn't happen directly. So, this line of thinking appears to agree with what you were taught. It does make sense. The risk I see is that if you are a bit too late with the herbicide, you have allowed for another year's seed set, which is what tends to happen with this method and Whitetop. Colleen -----Original Message----- From: pbs-bounces@lists.ibiblio.org [mailto:pbs-bounces@lists.ibiblio.org] On Behalf Of J. Denys Bourque Sent: Thursday, April 04, 2013 11:01 AM To: Pacific Bulb Society Subject: Re: [pbs] Vinegar for weeds Dell writes that his vinegar potion only kills the tops of undesired plants... On this, long ago in our "Kill-raspberries-et-al.-that-competes-against-spruce-&-fir" course in Forest Management @ UNB, Canada, we were instilled with the notion that "weeds" are best dealt with near the end of the growing season when they have used up all their resources. Perhaps timing is a concern here. J. Denys Bourque Saint-Jacques, NB CANADA >________________________________ > From: "ds429@comcast.net" <ds429@comcast.net> >To: Pacific Bulb Society <pbs@lists.ibiblio.org> >Sent: Thursday, April 4, 2013 2:32:52 PM >Subject: Re: [pbs] Vinegar for weeds > >I have used "horticultural vinegar" (20%) on my most hated weed, mugwort (Artemesia sp), and it only kills the tops. New growth returns from the roots in no time. > >Dell > >----- Original Message ----- > >From: "Leo A. Martin" <leo@possi.org> >To: pbs@lists.ibiblio.org >Sent: Thursday, April 4, 2013 1:19:04 PM >Subject: Re: [pbs] Vinegar for weeds > >I couldn't tell whether anybody replied to Alberto's query about using vinegar on weeds. >Yes, it works on most but not all weeds. Spray cooking vinegar (5% >acidity as sold in the USA) on young weed seedlings. It seems less >effective on older seedlings or plants, especially dandelions. > >By the way, judging by the number of people writing me privately for >unobtainable plant material, this is by far the most gullible plant group to which I subscribe. > >Leo Martin > >_______________________________________________ >pbs mailing list >pbs@lists.ibiblio.org >http://pacificbulbsociety.org/list.php >http://pacificbulbsociety.org/pbswiki/ >_______________________________________________ >pbs mailing list >pbs@lists.ibiblio.org >http://pacificbulbsociety.org/list.php >http://pacificbulbsociety.org/pbswiki/ > > >