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Soybean Seed
Quality and Seed Treatment
Pat Lipps, Anne Dorrance and Dennis Mills
Department of Plant Pathology, OARDC
Fungicide seed treatments on
soybeans are encouraged for 2001 for the three following reasons:
- Poor quality soybean seed, as a
result of poor growing conditions, are very fragile with
cracked seed coats. Germination in these cases is reduced due
to the physical damage. Fungicide seed treatments will help
protect this seed from soil pathogens if the seed is exposed
to excessively wet soil or other stresses following planting.
- Phomopsis seed rot is a
seed-borne disease that affects the germination of seed. Most
seed treatment fungicides (Agrosol T, Rival, Maxim and others)
are effective in increasing the germination of seed affected
by Phomopsis 15 to 20%. Seed lots with
germination below 70% should not be used for seed.
- There are now races of Phytophthora
present in many Ohio fields that are able to cause disease
on varieties with many of the Rps genes (Rps 1a, 1b, 1c, 1k,
3a and 6). Choosing varieties with high levels of partial
resistance is more important than ever before. Since partial
resistance becomes effective after plants begin to develop
their true leaves, seed treatment is needed to protect these
plants during germination and emergence growth stages. For
these fields with a history of Phytophthora, wet fields,
no-till or continuous beans, the higher rates of Allegiance
and Apron XL are needed to achieve effective control of Phytophthora
(Allegiance @ 1.5 fl. oz./cwt and Apron XL @ 0.64 fl.
oz./cwt). These rates will also control Pythium seed rot and
damping off. Allegiance and Apron XL can be combined with any
of the other seed treatment fungicides labeled on soybeans to
achieve broader spectrum of control.
Refer to the efficacy tables below
for both commercial and on-farm seed treatments.
Efficacy of Commercial Soybean Seed
Treatments
|
Product |
Active
Ingredient |
Phomopsis
seed rot |
Phytophthora
damping off |
Pythium
damping off |
Rhizoctonia
seedling
blight |
|
Agrosol FL |
Captan, TBZ |
G |
N |
P |
F |
|
Agrosol T |
Thiram, TBZ |
G |
N |
N |
F |
|
Allegiance |
Metalaxyl |
N |
E* |
E |
N |
|
Apron XL |
Mefenoxam |
N |
E* |
E |
N |
|
Captan |
Captan |
G |
N |
P |
P |
|
Captan T |
Captan, TBZ |
G |
N |
F |
P |
|
Maxim |
Fludioxonil |
G |
N |
N |
G |
|
Rival |
Captan, PCNB,
TBZ |
G |
N |
P |
G |
|
Thiram |
Thiram |
G |
N |
P |
F |
Efficacy based on labeled rates of
active ingredient for each material.
Efficacy rating scale: E = excellent, G =good, F= fair, P = poor,
N = no activity, ND = no data.
*Efficacy rating for Allegiance and Apron XL are based on the
higher labeled rates.
Several on-farm products and
systems are available, by either hopper-box treatment or auger
systems. Growers should read and follow label directions for both
the system and material.
Efficacy of On-Farm Soybean Seed
Treatments
|
Product |
Active
ingredient |
Phomopsis
Seed rot |
Phytophthora
Damping off |
Pythium
Damping off |
Rhizoctonia
Seedling
blight |
|
Allegiance FL |
Metalaxyl |
N |
E* |
E |
N |
|
Allegiance LS |
Metalaxyl |
N |
E* |
E |
N |
|
Apron XL LS |
Mefenoxam |
N |
E* |
E |
G |
|
Apron Maxx RTA |
Mefenoxam
Fludioxnil |
E |
E* |
E |
G |
|
Prevail |
Carboxin
PCNB
Metalaxyl |
E |
F |
E |
F |
|
Protector L/ Allegiance |
Thiram
Metalaxyl |
G |
F |
E |
G |
|
Stiletto |
Carboxin
Thiram
Metalaxyl |
E |
F |
E |
G |
|
System3 |
PCNB
Metalaxyl
Bacillus
subtilis |
E |
F |
E |
G |
Efficacy based on labeled rates of
active ingredient for each material.
Efficacy rating scale: E=excellent, G=good, F=fair, P=poor, N=no
activity, ND=no data
*At higher labeled rates
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