[compost_tea] Slay Dandelions with Common Fungi, and Bacteria?

From: Ryan, Matthew <matthew.ryan_at_rodaleinst.org>
Date: Thu, 4 Mar 2004 09:47:31 -0500


Hi Everyone,


The article reminded me of another biocontrol agent that has been
isolated from Canada thistle. Almost the exact same mechanism, but
different organism. The is a bacterium, rather than a fungus like the
Phoma macrostoma. Maybe a combination of the two would be more
effective as a biological herbicide? -Matt


ASSESSMENT OF PSEUDOMONAS SYRINGAE PV. TAGETIS AS A BIOCONTROL AGENT FOR
CANADA THISTLE (CIRSIUM ARVENSE)


        Author(s):
        
        GRONWALD JOHN W
        PLAISANCE KATHRYN L
        IDE DONALD A
        WYSE DONALD L
        

        Interpretive Summary:
        
        Canada thistle is a noxious, invasive weed that infests range
and cropland in the north central part of the U.S. Although herbicides
can aid in the control of this weed, they can also have adverse effects
on the environment. Pseudomonas syringae pv. tagetis (Pst) is a
naturally occurring bacterium that infects Canada thistle. This
bacterium causes the weed to become yellow because it blocks the
synthesis of green pigments in leaves that are used to harvest the sun's
energy. Previous research showed that spraying Pst on Canada thistle
with a soap-like compound allowed the bacterium to infect the weed.
Applying Pst in this manner has no effect on soybean. We evaluated the
effectiveness of Pst for controlling Canada thistle in soybean. Spraying
Canada thistle with Pst resulted in disease symptom expression within
one week after treatment. However, within a month after treatment,
Canada thistle plants had outgrown these symptoms. Pst treatment reduced
shoot biomass of Canada thistle by 20 to 30% and seedhead production by
80%. However, treated plants were not killed. Overall, the results show
that while foliar application of Pst causes a significant reduction in
seedhead production by Canada thistle, it does not provide effective
control of vegetative growth. Future research will need to focus on
developing a spray formulation that increases the effectiveness of this
potential biocontrol agent.





Received on Thu Mar 04 2004 - 10:10:31 EST

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