sustainable potting media

sustainable potting media
Tim Eck via pbs (Mon, 18 Dec 2023 04:23:08 PST)

Luckily they quietly took the bad stuff - arsenic - out of pressure treated
wood a few decades ago when a demographic study (of well water in Formosa,
I think) showed it was proportionally carcinogenic at all levels. Now, I
think, they only use copper naphthenate for fungicide in pressure treating.
Personally, I am banking on The American Chestnut Foundation (TACF)
eventually solving the problem altogether because chestnut wood seems to
persist untreated for decades in ground contact.
For those interested, TACF has withdrawn its support for their transgenic
chestnut, partially due to their dissatisfaction with the growth rate using
a constitutive promoter (always on) for the OxO gene (destroys oxalic acid
secreted by the blight fungus). But the departure from SUNY's deregulation
request was precipitated by the discovery of a misidentification of the
clone they were testing early in the program. TACF will continue
investigating transgenic (but with wound induced promoters) as well as
hybridizing and biocontrol.
If anyone is interested in breeding blight resistant forest quality
chestnut trees, I have (free) seed for the final generation of a breeding
program I have been working on for a few decades. The ideal plot would be
about two acres of well-drained cornfield.
Tim

On Sun, Dec 17, 2023 at 9:29 PM Laura Grant via pbs <
pbs@lists.pacificbulbsociety.net> wrote:

We had a bad experience with composted " pine bark" delivered by a local
supplier. After most of the truck load was spread around the favorite
plants we noticed some losses. When we came to the bottom of the pile we
found labels that read "pressure treated".
Laura

On Sun, Dec 17, 2023 at 3:33 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

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

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

bought bags of "garden topsoil" from certified organic sources for

this

purpose. The main things I avoid are bark, which appears to be

attacked

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

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

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

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.

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

bacteria and fungi inhabiting half-dead trees would present a problem

bulbs or if they are sufficiently host-specific that they are harmless

potting media. For all I know, they might be the same microbes

working

composters.

Any mycologists out there who could weigh in on this?
Bob Zone 7
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