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Processors and Growers Research Organisation |
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Seed Quality |
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Seed Testing:
Seed Quality
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Tenderometer
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Good
seed is essential for successful crop production. Seed
should have a high germination and be free from harmful
pests, diseases and disorders. |
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Germination &
Seed Vigour
The ability of seed to germinate and produce a healthy
plant is essential. In germination tests, seeds are grown
in controlled conditions and records made of healthy,
dead and abnormal seedlings.
A satisfactory germination result is the basis for a more
detailed examination for seed-borne pests, diseases and
disorders.
Vining peas and green beans can suffer from poor field
emergence when sown in cold, wet soil conditions. Seed
which is prone to this problem is said to be low vigour.
Tests are available to determine the seed vigour of both
vining peas and green beans. The former are evaluated by
means of an electrical conductivity test while the vigour
of beans is determined by a biochemical staining
technique.
Combining peas and field beans seldom suffer from such
problems and therefore seed vigour testing is not
relevant in the majority of cases. |
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Fungal Diseases
With peas,
these closely related fungi are usually referred to as
the Ascochyta complex, while with beans, Ascochyta fabae
can be the most damaging disease. In both cases, it is
essential to know the infection level. For beans, when
infection exceeds 3%, seed should not be used. If
infection is 1% or less, no treatment is needed, but
where infection is between 1% and 3%, seed should be
treated. The pea infection threshold is 5% but
between this figure and the upper limit of 30%, seed can
still be used providing it is suitably treated.
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Peas -
leaf & pod spot (Ascochyta pisi, Mycosphaerella pinodes)
Broad &
field beans - leaf & pod spot (Ascochyta fabae)
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Peas -
bacterial blight (Pseudomonas syringae pv pisi)
Beans -
halo blight (Pseudomonas syringae pv phaseolicola)
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Bacterial Diseases
Both diseases
have the potential to cause severe crop loss. Rigorous
seed testing and with green beans seed crop inspection,
has restricted disease development.
In the UK, bacterial blight has caused crop loss in
winter peas particularly following a late spring frost.
It is therefore important to use only tested seed which
has been found to be free from infection.
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Virus Diseases & Pests
Peas - Pea
Seed-borne Mosaic Virus(PSbMV)
PSbMV has caused severe losses in peas. An ELISA
test to detect the presence of PSbMV in the seed has been
developed to ensure that only seed with a low level of
infection is used and an infection threshold of 5% has
been established.
Broad and field
beans - Stem and bulb eelworm (Ditylenchus dipsaci)
This
pest is seed-borne and causes problems, particularly when
farm-saved seed has been multiplied for several
generations. The pest can also be soil-borne and can
infest a wide range of crops, including bulbs and onions.
For this reason a zero tolerance is recommended.
Seed testing service
Comprehensive
seed tests for all types of peas and beans are available
from PGRO, with work being undertaken by qualified
analysts. The seed testing price list gives further
details. Experienced staff can also help with the
interpretation of the results and advise on the
suitability of seed lots plus any need for special seed
treatments.
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