Good point. I knew it got hot enough to kill most pathogens but was not aware it decomposes pesticides. I rather doubt it destroys those organo-halide bonds but they aren't so common anymore. On Sun, Dec 17, 2023 at 2:38 PM Nan Sterman via pbs < pbs@lists.pacificbulbsociety.net> wrote: > Municipal composters all have to adhere to very strict ISO requirements > and test regularly. They all hot compost and at the hot compost temps, > pesticides and pathogens break down so they are not a concern. The testing > is their - and you - assurance of that. All that testing is intended to > ensure there are no problems with the municipal composts. I am actually > more concerned about using compost from non regulated facilities like > nurseries. > > Nan > > Sent from my eye eye phone. All typos are the captain’s fault. > > > On Dec 17, 2023, at 11:21 AM, Jane McGary via pbs < > pbs@lists.pacificbulbsociety.net> wrote: > > > > As Mark mentioned, municipal compost in this area includes lawn > clippings, and I don't use it either for fear of herbicide residue. I do > use a mulch containing compost, but the company that provides it tests the > ingredients for residual harmful chemicals. I like to use a minor > proportion of organic material in bulb potting mix, and most recently I > bought bags of "garden topsoil" from certified organic sources for this > purpose. The main things I avoid are bark, which appears to be attacked by > a fungus with visible mycelia that can also attack the tunics of dormant > bulbs, and perlite and vermiculite, which have no value to the plants and > tend to rise to the top; the latter are also said to be dangerous if you > inhale the dust. > > > > When I started growing bulbs seriously around 1990, I had a country > place with an alder woodland on part of it (alders are nitrogen fixers). I > screened the topsoil to make up part of the bulb mix, along with ground > pumice and coarse upriver sand. This worked very well and there seemed to > be no problem with disease, even though the leafmold surely contained all > sorts of microorganisms. I did not use this mix for seed sowing, but > instead used peat as a minor component. I think sterilizing seed soil is > pointless unless you can maintain laboratory conditions, since spores, > etc., will arrive in the air. I used to grow Meconopsis by surface-sowing > on milled sphagnum moss (not peat) as a preventive measure, but since > moving to a place where that genus doesn't grow well, I gave that up. > > > > Probably the hardy, summer-dormant bulbs I grow are not as vulnerable to > disease as the tropical and subtropical species some PBS members have. > Surplus bulbs that I've removed to the garden mostly flourish there despite > weekly irrigation in most places. It has always seemed to me that > cultivating these plants as "hard" as they can tolerate results in > healthier populations that appear in character. Coming to bulb growing from > the perspective of alpine and rock gardening is no doubt an influence. My > bulb house is very like an alpine house, but not even minimally frost-free. > Many PBS members might despair at a situation where South African bulbs and > tropical amaryllids can't be grown, but I like the relative freedom of this > kind of gardening. > > > > Jane McGary, Portland, Oregon, USA > > > > > >> On 12/17/2023 8:18 AM, Robert Lauf via pbs wrote: > >> Regarding arborist debris, I'd be curious to know whether the kinds of > bacteria and fungi inhabiting half-dead trees would present a problem to > bulbs or if they are sufficiently host-specific that they are harmless in > potting media. For all I know, they might be the same microbes working in > composters. > >> Any mycologists out there who could weigh in on this? > >> Bob Zone 7 > >> _______________________________________________ > >> pbs mailing list > >> pbs@lists.pacificbulbsociety.net > >> https://lists.pacificbulbsociety.net/cgi-bin/… > >> Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> > >> PBS Forum latest: > https://pacificbulbsociety.org/pbsforum/index.php/… > > _______________________________________________ > > pbs mailing list > > pbs@lists.pacificbulbsociety.net > > https://lists.pacificbulbsociety.net/cgi-bin/… > > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> > > PBS Forum latest: > https://pacificbulbsociety.org/pbsforum/index.php/… > _______________________________________________ > pbs mailing list > pbs@lists.pacificbulbsociety.net > https://lists.pacificbulbsociety.net/cgi-bin/… > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> > PBS Forum latest: > https://pacificbulbsociety.org/pbsforum/index.php/… > _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net https://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> PBS Forum https://…