[compost_tea] Phytopathology journal article on compost tea, November 2004

From: Steve Diver <steved_at_ncat.org>
Date: Wed, 20 Oct 2004 01:36:43 -0000

Compost Tea as a Container Medium Drench for Suppressing
Seedling Damping-Off Caused by Pythium ultimum.

Steven J. Scheuerell and Walter F. Mahaffee.

Phytopathology 94:1156-1163.  November 2004.
Volume 94, Number 11

http://www.apsnet.org/phyto/


Abstract:

Compost tea is being used increasingly in agricultural production
to control plant diseases. However, there has been limited
investigation relating disease control efficacy to various compost
tea production methods, particularly compost tea produced with
active aeration and additives to increase microbial population
densities in compost tea. Aerated compost tea (ACT) and nonaerated
compost tea (NCT), produced with or without additives, was
investigated for the suppression of damping-off of cucumber
caused by Pythium ultimum. Compost tea was used to drench
soilless container medium inoculated with P. ultimum;
effect on damping-off ranged from not suppressive to
consistently suppressive depending on the method used to produce
the tea. The most consistent formulation for damping-off
suppression was ACT produced with kelp and humic acid additives.

Producing ACT with a molasses-based additive inconsistently
suppressed damping-off; evidence suggests that residual nutrients
can interfere with disease suppression. Heating or diluting compost
tea negated suppression. Across all compost tea samples, there was
no significant relationship of bacterial populations, measured as
active cells, total cells, or CFU, to disease suppression. However,
for all ACT produced without the molasses-based additive, there
was a threshold of bacterial population density (6 log(10) active
cells per ml, 7.48 log(10) total cells per ml, or 7 log(10)
CFU per ml) above which compost teas were suppressive.




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Received on Tue Oct 19 2004 - 23:00:43 EDT

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