•
RESEARCHDIARY
•
THE
VEGETABLE
FARMER •
JANUARY 2017
Researchers at Cornell University
have looked at developing seed
coating formulations using soy
flour, a sustainable, inexpensive,
and green source, as a
biostimulant using broccoli as the
model system.
A 10% suspension of soy flour
was used as the seed treatment
binder in all coatings. The solid
particulate filler was composed of
mixtures of soy flour, cellulose, and
diatomaceous earth, together
termed as SCD. All SCD
components were homogenized in
water, then dried and ground to a
fine particle size <106 µm
(HortScience).
The SCD coatings were applied
with rotary pan seed coating
equipment at 25% of the seed
weight. Increasing the proportion
of soy flour increased the seed
coating strength and also the time
for the coating to disintegrate after
soaking inwater. As a result, the
seed coatings the germination rate
comparedwith the nontreated
control.
However, the 10-day-old seedling
root and shoot growth showed
significant improvement for all SCD
coating treatments comparedwith
controls. Plant growth and
development was alsomeasured
after 30 days in the greenhouse.
Freshweight (FW) and dry weight
(DW), leaf area, plant height, leaf
development, Soil-Plant Analyses
Development (SPAD) index
(chlorophyll measurement), and
nitrogen (N) per plant were all
greater from coatings with 30%,
40%, and 50% soy flour than the
noncoated control.
Nitrogen, from the soy flour
applied in the seed coatings,
ranged from 0.024 to 0.073mg
per seed, while the enhanced N
per plant ranged from 1.7 to 8.5
mg. Nitrogen applied in the seed
coating only accounted for 1% to
2% of the enhanced N in the
plants, indicating the soy flour
acted as a biostimulant rather than
a fertilizer.
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by Dr. David Pennell
Biostimulant seed coating formulations for broccoli
Biocontrol products for Rhizoctonia of potato
Four commercial biocontrol
formulations - (
Bacillus
subtilis
GB03,
Burkholderia
ambifaria
typeWisconsin isolate
J82,
Trichoderma virens
Gl-21,
and
Trichoderma harzianum
strain
T-22), a chemical seed treatment
(thiophanate-methyl, mancozeb,
and cymoxanil mixture, TMC),
and a combination chemical /
biological treatment, were
comparedwith no-pathogen and
pathogen-treated controls, and
monitored in two field seasons,
by USDA, ARS, scientists at the
University of Maine, for their
effects on the development of
Rhizoctonia disease of potato and
soil microbial community
characteristics (Crop Protection).
All treatments reduced the
incidence and severity of stem
canker (37–75% reduction)
relative to the pathogen control
over both years, with the best
control provided by B. subtilis and
the combination
chemical/biological treatment
(TMC/Bamb). Both bacterial
treatments (
B. subtilis
and
Bu.
ambifaria
) reduced severity of
black scurf in both years, and T.
virens reduced scurf in one year,
with reductions of 11–20%
relative to the pathogen control.
Over both years, the B
. subtilis,
T. virens
, and TMC/Bamb
treatments increased total and
marketable yield, and
Bu.
Ambifaria
increasedmarketable
yield, by 11–15% relative to the
pathogen control. Substantial
populations of the added fungal
agents, but not the bacteria, were
detected in soil at the end of the
growing season. Bacterial
biocontrol treatments generally
resulted in higher microbial
activity. This indicates that
biocontrol treatments can assist
in the control of Rhizoctonia
disease of potato, persist in soil
to some degree, and have
significant effects on soil
microbial communities long after
application.
