Biologicals – Good Microbes Vs. Bad Microbes
When you first
move to a
you may not know where to shop for food, or how to get from one
place to another, or even the safe areas from the dangerous areas.
You are at a disadvantage to those who live and are already
established in the city.
When you place a
biological fungicide (microbe) on a seed, and plant that seed in the
soil, it’s much like a person moving to a new city; the introduced
microbes are at a disadvantage. Establishing a population of
introduced microbes in the soil is difficult. The established
microbes occupy the spaces where the food is, and are
established, because they are especially adapted to grow and survive
under those particular conditions.
Microbial Soil Populations
are many microbes in the soil. Most neither help nor hurt
plants. A few are directly beneficial to plants by promoting
plant growth or by making nutrients available to the plant.
There are also a few that can cause plant diseases. Those that
cause plant diseases, we’ll call the “bad microbes”.
And then… there
are those microbes that do battle with the microbes that cause plant
diseases. These we will call the “good microbes”.
have looked for, and found “good microbes” for possible use as
biological fungicides. When a scientist finds a “good microbe”
in the soil and then applies the purified “good microbe” back on a
seed, he/she is asking the microbe to establish itself in the soil
and prevent the “bad microbes” from causing plant
diseases. This is a lot to ask.
In order to
establish introduced “good microbes” in the soil, and have them
protect the plant, there must be something about your “good microbe”
that gives it an advantage over the well established microbes in the
soil, making the odds better for the “good microbes” to protect the
plant against the “bad microbes” that cause plant diseases.
Two Ways that “Good Microbes” can beat “Bad Microbes”
develop biological seed treatments look for “good microbes” that are
antagonistic against the “bad microbes”. Some “good microbes”
can release substances that prevent growth or kill the “bad
microbes”. The picture shows bacteria in the center of the
plate with fungi growing all around it. The bacteria are
releasing a substance that prevents the fungi from growing any where
near the “good microbe” in the center of the plate.
Establishment of this “good microbe” on plant roots could create a
zone of disease protection for the plant.
strategy, is to find a “good microbe” that is exceptionally fast
growing, and able to physically occupy most of the spaces where
there’s food on the seed and plant root. If you can occupy
these nutrient rich spaces before a “bad microbe” can get to them,
you can prevent infection by the “bad microbe”, and limit plant
Biological Fungicides on the Market
There are many
“good microbe” biological fungicides available on the market as seed
treatments. In general, chemical fungicides still seem to be
the most consistently effective seed treatments. It has been
suggested that combining chemical seed treatments with biological
seed treatments may extend the length of plant protection over
chemicals alone. It has also been thought, that a chemical
seed treatment that deters the growth of soil microbes without
hurting the “good microbes” may give the “good microbe” enough of an
advantage to establish itself on the plant. Both of these
thoughts suggest a possible synergistic relationship between certain
chemicals and biological fungicides in the future. Time will
we’ll talk about “Seed Dormancy – A physiological Door we can Open”.