I do the Lucas Formula for coco. I water to waste some, depending on how lazy/busy I get.
Most of the stuff in my myco's (thanks for the abbreviation, I can never remember how to spell that) supposedly gets killed by that ratio of fert.
I have two kinds of tricoderma in mine among about 35 others. It is Plant Success.
So some of the stuff will survive?
I could start using it again, I just thought it was a waste in coco with the Lucas formula.
Here you go:
http://www.puyallup.wsu.edu/~Linda Chalker-Scott/Horticultural Myths_files/Myths/Mycorrhizae.pdf
Y
ouve probably seen them beforethose white
threads too long and slender to be roots, yet
intimately associated with the root system of
your landscape and garden plants. They are fungal hyphae, and their association with many plant
hosts are collectively called mycorrhizae (myco = fungus, rhizae
= roots). These are primitive associations, thought to have arisen
hundreds of millions of years ago when vascular plants emerged
on land. Originally, mycorrhizal relationships were thought to be
unusual oddities; we now know that they are the rule, rather than
the exception, especially in woody plants. But, before you grab the
fungicide, lets get to know these plant partners.
Mycologists have divided mycorrhizal fungi into two categories depending on how intimate the relationship is: those whose
root-like hyphae surround and occasionally penetrate root tissues
(ectomycorrhizae; ecto = outside) and those whose hyphae
always enter the root cells (endomycorrhizae; endo = inside).
Though ectomycorrhizae are only found in a small percentage of
plant families, they are important partners of many woody plant
species, forming an extensive hyphal network throughout mulch
and topsoil layers. (If you use a coarse, woody mulch in your
landscape you can easily find fungal hyphae inside the mulch layer
and some of these could be mycorrhizal.) In contrast, endomycorrhizae are widely spread through hundreds of plant families and
most commonly represented by arbuscular (previously called
vesicular-arbuscular) species whose hyphal-root interfaces look
like branches (arbuscule = small tree) or balloons (vesicle = small
bladder). You might find these delicate structures associated with
the roots of your annual flowers or vegetables.
How do mycorrhizae infect plants?
Healthy soils contain vast repositories of mycorrhizal spores
in the coarse organic matter near the soil surface, where they germinate under moist, aerated conditions. As the hair-like hyphae
emerge from the spores, rain- and irrigation water create channels
down through the soil towards growing plant root tips. Roots
of plants under mild nutritional stress release chemical cues,
such as organic acids, that stimulate mycorrhizal growth. If the
hyphae encounter these receptive roots, they penetrate the cell
walls, pressing up into the cell membrane and creating chemical
passageways between the two partners. Multiple infection points
and hyphal branching create a cottony sheath around the roots
that extends far into the surrounding soil.
While inoculated roots tend to be shorter and more branched
than uninfected roots, their associated mycorrhizae act like root
hairs on steroids, extending far beyond the root mass to exploit
soil resources. Like microscopic miners, mycorrhizae discover
and extract soil water and nutrients from otherwise inaccessible
pockets.
The impact of mycorrhizal colonization goes far beyond an
individual plant. Most plants are colonized by a variety of mycorrhizal fungi, and most fungi have multiple hosts. Mycorrhizae
can link roots of different species, transferring nutrients to the
plants with highest demand. At the same time, the dense network of fine hyphae increase soil aggregates and improve soil
stability, while enhancing organic matter decomposition and
acidifing the root zone. The resulting network is a virtual fungal
freeway of nutrient and water acquisition and transfer.
Mycorrhizal populations are dynamic both in the soil and
on plant roots; different species may colonize plants at different times of their life cycle. New mycorrhizal infections can
develop from nearby active networks, dormant spores, and even
infected root fragments. And when soil conditions are changed
by activites as simple as adding organic matter, mycorrhizal species composition changes as well.
Why dont plants have defences
against mycorrhizal infection?
(See Symbiosis)
Most mycorrhizal relationships are mutualistic (you
scratch my back, Ill scratch yours) in that both partners receive
a significant benefit in exchange for sharing resources. Plants
transfer carbohydrates and B vitamins through the hyphae to
the fungi, which are non-photosynthetic and cant generate
their own food. In return, the fungi extensively colonize the
root surfaces and enhance the plants uptake of water and mineral nutrients.
Under well-watered, highly nutritive, crop-producing
conditions, there are reports of mycorrhizal parasitism, especially among monocots like wheat or corn whose fibrous root
structure is already well-adapted to nutrient uptake. In such
unnatural systems, the balance between the partners is shifted
so that mycorrhizae take more than they give. Not surprisingly,
mycorrhizal parasitism is rarely observed in home gardens and
landscapes, where woody plants with coarse root systems have
strong mycorrhizal associations.
What are the documented benefits
of mycorrhizae on plants?
Mycorrhizae increase both mobilization and uptake of
phosphate. This is especially important in alkaline or nutritionally deficient soils, where plant roots have a more difficult time
extracting phosphate. Improvements in phosphate nutrition as
a result of mycorrhizal colonization have been seen in leafy and
Mycorrhizae So, what the heck are they, anyway?
by Dr. Linda Chalker-Scott, WSU Science EditorPAGE 4 MASTERGARDENER
www.MasterGardenerOnline.com WINTER 2009
root vegetables, fruits, nuts, grains, and ornamental and timber
trees. Mycorrhizae also have a well-documented role in improving
plant survival and establishment;
leaf, root and shoot growth;
fruit/nut/oil yield;
competition for soil nutrients;
production of stimulatory plant hormones; and
nitrogen-fixing activity by leguminous plants.
Mycorrhizae provide economic and environmental benefits
as well, reducing both the need for phosphate fertilizers as well as
nutrient seepage to the environment.
The trees and shrubs in this landscape, top photo, owe their vigor to whats hiding underneath the protective wood chip
mulch. Rake back the mulch to discover healthy brown roots associated with the fine white hyphae of mycorrhizae.WINTER 2009
www.MasterGardenerOnline.com MASTERGARDENER PAGE 5
Protection from stress
With the documented benefits of mycorrhizal
fungi, its not surprising to find their plant partners
are more resistant to environmental stresses such as
drought. A consistent water supply via the mycorrhizal network allows plants to keep their stomates
open longer - and photosynthesize longer than
uncolonized plants. Likewise, mycorrhizae can
ameliorate salt stress (which also induces drought
in plant tissues), an important function in more
arid climates.
Since mycorrhizae create a dense fungal
network around plant roots, its not unexpected
that colonized plants are more resistant to root
pathogens, such as Verticillium, and pests, including
nematodes.
Not only do mycorrhizae improve the water
and nutrient status of plants, making them less susceptible to opportunistic pests and diseases, their
physical presence on the root limits the available
space for colonization by pathogens.
Mycorrhizae can also protect plants from heavy
metal stress (including aluminum, chromium, lead
and zinc) by preventing translocation of these toxic
minerals from the roots to the rest of the plant. The
protective nature of mycorrhizae could allow their
plant partners to be used in phytoremediation and
restoration efforts at a reduced risk to plant health.
What hurts mycorrhizae?
(See Phosphate and Mycorrhizae)
Healthy soils, whether in a home landscape or a
natural ecosystem, are naturally rich in mycorrhizal
species. When the soil chemistry is significantly
changed by the addition of pollutants or contaminants including salts, lime, heavy metals, and fungicides, many mycorrhizal species are unable to function. But by far the most damaging to mycorrhizal
health is excessive fertilizer application, especially
of those containing phosphate; this includes composted manure and many soilless potting mixes. With
a plethora of nutrients, plants are less dependent on
mycorrhizae, and competitive free-living microbes
thrive in nutrient-rich soils. Mycorrhizal fungi
retreat into the shadows, remaining inactive until
more hospitable soil conditions return.
Any activity that destroys soil structure like
wanton rototilling in a landscape - will also disrupt
the intricate mycorrhizal webs beneath the soil surface. Topsoil removal during construction is probably
the most damaging of all, as much of the inoculum
and all of the organic material and plants are eliminated. Adding insult to injury is the compaction
caused by heavy construction equipment, which
creates oxygen-depleted soils about as hospitable as
cement. Of course, mycorrhizal colonization and
Symbiosis
The Good, The Bad,
and Everything In Between
S
ymbiosis is a general term used to describe the interdependent
relationships among species. Three of these relationshipsmutualism, commensalism, and parasitismare divided by the thinnest of fine
lines. Understanding how these relationships develop and change over
time is both instructive and fascinating.
Parasitism occurs between a parasite and a host, through which the
parasite benefits and the host is harmed but not routinely killed. Usually
smaller than their hosts, parasiteslike aphids, spider mites, or scales
receive food or some other benefit crucial to their survival. The hosts resources are partially directed to the parasite at the hosts expense. Parasites
that kill their host are left without these necessary resources, so the most
successful parasites are those that are not lethal. Furthermore, successful
parasites avoid alerting hosts to their presence and slip past host defenses.
There are good reasons why the saliva of leeches and other bloodsuckers
often contains anaesthetizing agents! The various mistletoes, including
those used during winter holidays, are well-known examples of parasitic
plants.
Some organisms that depend upon a host for survival, apparently
neither harm nor help their host. These represent commensal relationshipsa good botanical example would be the epiphytic orchids living
in rainforest trees. In theory, these orchids cause no damage to their
host trees, though arguably an overloaded tree might suffer limb breakage. Some scientists do not believe true commensalism exists, arguing
that such close relationships must change the host species in some way.
For the sake of this discussion, however, well consider commensals to
be perfected parasitesthey are not organisms that induce a physical or
chemical defense from the host.
The best way to ensure a dependent organisms survival is to repay
its hostrather than attempting physically or chemically to dislodge the
foreign species, the host even invites invasion. Mutualistic relationships
confer benefits on both species involved, often to the extent that if one
species becomes extinct, the other ones demise is ensured. Many examples
of mutualism exist in nature; one of the best studied is the ant/plant
relationship which includes members of Acacia. These trees provide both
shelter and specialized food resources for ant colonies, which live in the
tree and vigorously attack grazing animals that disturb the hosts leaves.
Moreover, the ants are weeding perfectioniststhey descend the tree
and nip off any germinating seedlings that might compete for their trees
water and nutrients.
In my opinion, the most amazing example of symbiosis is found in the
cells of plants and animalsincluding you! We know that chloroplasts
and mitochondria both have their genetic origins in primitive singlecelled organisms that invaded other early life forms, though the exact
process is lost to evolutionary history. Over time, these endo-symbiotic
cells became part of their hosts biological makeup and vital to host survival. Neither photosynthesis nor cellular respiration could exist without
these two organelles, which contain their own circular DNA molecule
quite unlike the double helix found in the chromosomes of more complex
species. nPAGE 6 MASTERGARDENER
www.MasterGardenerOnline.com WINTER 2009
plant communities will eventually recover, but unnecessary soil
disruption should be avoided.
What types of activities or products can help
mycorrhizal establishment in landscapes?
(See Practical Information)
To encourage these hard-working and beneficial fungi in
your plant community, youve got to cut down the junk (plant)
food - stop using soluble phosphate fertilizer! If soil tests show
youve got too much phosphate already, research has found that
conservative additions of nitrogen fertilizer or organic material can increase mycorrhizal infectivity. Warm temperatures and
daylight favor mycorrhizal colonization, as does mild drought
or nutrient deficiency. Plant roots need to be receptive to infection, and the best way to ensure this is to avoid overwatering and
overfertilization. Other environmentally friendly practices, such
as reducing pesticide use and tilling while increasing the diversity
of plant materials will favor increased numbers and biodiversity
of mycorrhizal species.
Do mycorrhizal amendments work
in landscapes?
Mycorrhizal amendments are heaviy marketed as products
that will improve soil health and plant establishment in gardens
and landscapes. These products can be effective for inoculation of
sterilized container media, but scientific studies on urban landscapes and other real world systems report that these products
have no significant value. In general, plant species inoculated with
commercial products and installed into the landscape are equal
in performance to uninoculated controls (which quickly became
colonized with native fungi). While the addition of organic
matter has been found to stimulate growth of native mycorrhizal
populations, applying commercial mycorrhizal amendments is
generally ineffective and unnecessary, given the widespread presence of indigenous inoculum.
One recent study tested several commercially available products containing mycorrhizal fungi and various so-called biostimulants (e.g. kelp, humic acids, and yucca plant extract) on the
establishment and survival of four commonly used ornamental
trees and shrubs. In the researchers words, the treatments did
not lead to a significant improvement of plant growth of transplant survival compared to the untreated plants receiving routine
mulching with pine bark mulch alone.
From a practical standpoint, two realities emerge from all the
research done thus far:
Healthy soils naturally contain indigenous mycorrhizae.
Adding packaged mycorrhizae to such soils is a waste of money
and resources.
If soils are impaired to the point where indigenous mycorrhizal species cant survive, mycorrhizal amendments alone wont
help.
Beneficial microbes are important components of garden
and landscape soils, and the best way to cultivate their presence is
through thoughtful, sustainable horticultural practices. n
Phosphate and Mycorrhizae:
A Love/Hate Relationship
O
ne of the many benefits of mycorrhizal colonization
is that plant root uptake of phosphateespecially
unavailable formsis greatly increased. Yet numerous
studies have demonstrated that phosphate fertilizer is deadly
to mycorrhizal associations. How can these two realities
coexist?
When a plant senses that its tissues or the soil contains
enough phosphate, it no longer needs its mycorrhizal
partner and so becomes less receptive to infection by mycorrhizal spores. Phosphate amendmentespecially soluble
formswill inhibit mycorrhizal development on many
economically important plants. In non-agricultural systems,
such as grasslands, wetlands, and forests, phosphate addition
has a similar inhibitory effect on mycorrhizal infection. This
negative interaction has been experimentally demonstrated
and repeated in laboratories, greenhouses, nurseries, fields,
forests, and managed landscapes.
Often this inhibition is an issue of moderation. High
levels of soluble phosphate nearly always squelch mycorrhizal activity, while lower levels are sometimes syngergistic
with mycorrhizae, especially if phosphate is unavailable
due to soil alkalinity. One form of this mineralrock
phosphatecan be particularly difficult for plant roots to
mobilize. Mycorrhizae, however, can easily solubilize this
mineral and transport it to the plant roots. Since plant roots
perceive a lack of available phosphate, they are receptive to
mycorrhizal infection and subsequent uptake of this phosphate source.
But, as with any other fertilizer, rock phosphate should
never be added to a landscape unless soil tests indicate a
nutrient deficiency. n
Practical information
for cultivating mycorrhizae
Coarse organic mulch is good reservoir for spores, and
litter type affects mycorrhizal diversity. Try to use a mixed
mulching material, such as arborist wood chips, which will
help reduce nutrient runoff and leakage.
Living mulch can facilitate mycorrhizal networks between plants. Consider using some of the many low-growing,
drought-tolerant ground covers available commercially.
Beneficial bacteria can assist in mycorrhizal activity.
Eliminate unnecessary use of broad-spectrum bacteriocides.
Diverse landscape plantings favor mycorrhizal diversity. Use a variety of trees, shrubs, ground covers, herbaceoous
perennials, bulbs, and annuals.
Strongly mycorrhizal plantsthose with coarse root
systemscan alleviate phosphate overloads in landscape
soils and enhance mycorrhizal diversity