Nan is right that testing is done on compost but heat doesn’t break down pesticides, some have insane half life times and really sunshine and UV is one of the best “decomposers” of pesticides. The test they are supposed to run for pesticide presence in compost is called a cucumber bioassay test, basically cucumbers are super susceptible to toxins so you germinate a handful of seedlings and test the survival rates. It’s worth asking your compost source for test results and be sure to note the date. They definitely aren’t as frequent with testing as you would think and having been “burned” by pesticide loaded municipal compost on projects before I won’t use it in a potting soil under any circumstances but it is worth testing on your own as cucumber seeds are an easy way to test your own local source. I do live in the “grass seed capital of the world” and around here people pour so much chemicals on lawns it’s bonkers. Mark Illahe Nursery and Gardens Salem, Oregon > On Dec 17, 2023, at 12:33 PM, Jan Jeddeloh via pbs <pbs@lists.pacificbulbsociety.net> wrote: > > I used to get tree trimmer waste at my old place. Some of those tree trimmers also do some maintenance and I once got a load that that wasn’t straight trees. It was filled with crap from blowing off parking lots etc. I learned my lesson. Always ask what’s in the truck before they dump. > > Jan > >> On Dec 17, 2023, at 12:23 PM, Arnold Trachtenberg via pbs <pbs@lists.pacificbulbsociety.net> wrote: >> >> We had the company deliver a load of compost to our community garden and it was full of debris and garbage from street pick up. >> I've never seen any lab work on the compost they sell. It may be tested different in CA, but not here in NJ. >> I can imagine the petrochemicals, heavy metals and brake lining debris picked up when leaves are vacuumed up in the fall from our streets. >> >> >> Arnold >> >> On Sunday, December 17, 2023 at 02:54:59 PM EST, Tim Eck via pbs <pbs@lists.pacificbulbsociety.net> wrote: >> >> 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://… >> >> _______________________________________________ >> pbs mailing list >> pbs@lists.pacificbulbsociety.net >> https://lists.pacificbulbsociety.net/cgi-bin/… >> Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> >> PBS Forum https://… > > _______________________________________________ > pbs mailing list > pbs@lists.pacificbulbsociety.net > https://lists.pacificbulbsociety.net/cgi-bin/… > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> > PBS Forum https://… _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net https://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> PBS Forum https://…