Agriculture Reference
In-Depth Information
Table 9.1
Examples of variation in the level of disease suppression after foliar application of aer-
ated compost teas (ACTs)
Pathogen, Disease, Host
ACT treatment
Disease suppression
Reference
Botrytis cinerea
, grey
mould, strawberry
Bi-weekly applications in
the field
Small but significant
reduction in disease inci-
dence for fruit scored in
the highest category for
disease severity (51-95 %
surface area infected),
relative to water or non-
treated control treatments
Welke (
2004
)
Botrytis cinerea
, grey
mould, geranium
Single foliar application
to greenhouse-grown
seedlings subsequently
inoculated with the
pathogen
Only one of six ACTs
reduced disease severity
slightly when compared
with non-treated, inocu-
lated control plants
Scheuerell
and Mahaffee
(
2006
)
Botrytis cinerea
, grey
mould, geranium
As above but ACTs
amended with a mixture
of kelp, rock dust and
humic acids
Three of six batches of
amended ACT reduced
disease severity slightly
when compared with
non-treated, inoculated
control plants
Scheuerell
and Mahaffee
(
2006
)
Alternaria solani
, early
blight, tomato;
Alternaria
porri
, early blight, onion
Foliage sprayed in green-
house and field trials
Reduced disease
incidence to the same
degree as conventional
treatments
Haggag and
Saber (
2007
)
Erysiphe necator
, pow-
dery mildew, grapevine
ACT prepared from
immature compost;
multiple applications at
two vineyards in different
growing seasons
Suppressed disease to
< 1 % mean severity on
Chardonnay leaves (non-
treated 79 % severity)
and bunches (non-treated
77 % severity), and on
Riesling leaves (non-
treated 24 % severity)
Evans et al.
(
2013
)
Botrytis cinerea
, bunch
rot, grapevine
As above
Reduced the incidence
of Chardonnay bunches
with latent
B. cinerea
and
Riesling bunches with
sporulating
B. cinerea
Evans et al.
(
2013
)
The electrical conductivity (EC) of compost is determined by the initial ingredi-
ents and compost maturity. Early secondary mesophilic compost has a much higher
conductivity than late secondary mesophilic compost and the maturation process
reduces the level of conductivity through leaching of salts and/or through microbial
osmotic activity (Lau and Wong
2001
). Electrical conductivity (EC) in the result-
ing compost tea should be tested prior to application to the crop canopy so that any
risk of phytotoxicity due to excess salt is minimised. Ideally, the EC of compost tea
should be as low as the level tolerated by the target crop plant and/or crop variety.
Salts generally found in compost include potassium chloride, sodium chloride, vari-
ous nitrates, compounds involving sulfates, calcium, magnesium, and potassium
