[compost_tea] Re: Health & Safety Spraying Tea

From: chris reid <reidchris_at_earthlink.net>
Date: Sat, 06 Dec 2003 09:28:59 -0500

Brian,

re: Ted Peterson's post, one size anthracnose does not fit all. There are
different organisms specific to different hosts, and they vary in virulence.
For example, "dogwood anthracnose" which has traveled up and down the East
Coast in the US has been contributing to the demise of Cornus florida, our
native dogwood in recent years. According to an extension specialist at
Cornell University, this anthracnose, which does affect the vascular system
of the tree and can lead to its death, is typically OPPORTUNISTIC after the
tree has been weakened by some other condition or disease. Whether that
condition is effects of climate change, being planted too deeply (a frequent
problem here), a root disease such as some kind of Phytophthora or other
cause, that particular anthracnose tends to attack after other conditions
favor it. This same agent reports that the virulence of that anthracnose
appears to be decreasing in recent years and is less of a problem than it
was. I don't know if that is his personal opinion or whether there has
been some systematic approach to making this determination.

But you are talking about some kind of plane tree (which one?). The
anthracnose that affects the sycamores and London plane trees at the NY
Botanical Garden can defoliate the tree, and then it refoliates in a few
weeks. This has happened sometimes twice in the year. The plants are still
going. So -- it isn't a given here in US that the anthracnose will kill the
sycamore or the London plane tree.

BUT -- You are saying your experience is that the anthracnose prevents the
tree from leafing out and thus leaves it defoliated. So, either you are
dealing with a different kind of anthracnose or a different disease from
what Ted Peterson and I have experienced in the USA. Do you know what
organism you're dealing with (Latin name)? Does this anthracnose affect the
vascular system of the tree? (Often when vascular system is affected, you
will see staining in the vascular tissues when you cut off a twig or
affected branch).

This is where some net research and correspondence with highly trained plant
pathologists and consulting arborists might lead to some info as to what any
other precipitating factors might be in the particular disease of the
particular tree you are dealing with. Such factors as mineral balance in
the soil, conditions for the tree (climatic, soil texture/moisture levels),
soil food web considerations may set the tree up for infection. If you
apply tea and there are other aggravating factors, foliar tea may not get at
the problem.

As a theoretical example of a problem that may appear to be one thing but
be stimulated by another, here is a quote from the book PRINCIPLES AND
APPLICATIONS OF SOIL MICROBIOLOGY (David Sylvia et al.), chapter 6 "Protozoa
and Nematodes" by Elaine R. Ingham: "Nematodes can influence the production
and accumulation of plant growth factors. Increased hormone concentrations
in nematode-infected plants may contribute to greater infection by
wilt-causing organisms, because these growth factors make host tissues
easier to penetrate by maintaining cells in a rapidly dividing, juvenile
state. Plant pathogens can also affect nutrients released by roots, which
might affect decomposer and mycorrhizal fungi as well as root pathogens.
The composition and quantity of exudate compounds can be altered, damaged
plant cells can leak nutrients, and pieces of damaged root can become
available as substrate for rhizosphere microorganisms. Elements such as
calcium, magnesium, sodium, potassium, iron and copper are exuded in greater
quantity from roots infected with Meloidogyne sp., a plant-feeding
nematode."

Okay, be clear everyone, I am NOT saying this is the problem! I am pointing
out that there's a heck of a lot of info that never makes it into the
popular literature --and by popular, I also mean much of what the average
arborist (at least in the US) has at his/her disposal for identification and
management of disease.

A lot of applied science (typical horticultural) information doesn't delve
into this -- so I find I end up going in circles and hearing the same thing
over and over again. It's amazing how quickly I can tap into useful info
when I get out of that loop. So -- I recommend getting outside the info loop
you're in and seeing what you can learn. Forgive me if you've already done
this.

In relation to precautions when spraying tea, here is an opinion. My own
personal preference would be not to be casual about it. You are spraying
undifferentiated living organisms. Whether or not in theory "tea is safe,"
each time you spray tea, you are spraying something slightly different. Tea
made with compost that has incompletely composted manure and spends any time
anaerobic could have human pathogens in it. In *theory* any viruses in the
soil don't need a critical mass to cause infection the way bacteria do. One
virus is enough. So - what precautions do you use when you're spraying the
toxic stuff? Why not use the same precautions - mask, long sleeves, don't
spray on windy day, restrict entry till the tea is dry, etc. There's no
need to flout the belief that it's safe.

Chances are, what you are spraying IS much, much safer than the typical
pesticides out there but since you can't prove it unequivocally,
precautionary protection will protect you from public hysteria and also show
that you are respectful for the *potential* for problems that any biological
entity might in theory bring with it.

If we have any consulting arborists on the list, how about giving Brian a
hand with this?

Chris Reid




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Received on Sat Dec 06 2003 - 11:43:06 EST

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