Swathing
When swathing, leave a stubble of about 10 to 15 cm (4 to 6
in.) to hold the swath off the ground and facilitate drying.
To prevent blowing of the swath by strong winds, flax swaths
should be rolled. Swathed flax may be ready to combine after
exposure to a few days of dry weather. The swath may be
threshed when the leaves and stems are dry enough and the
seeds rattle in the boll, or the seed has dried to the desired
moisture level as indicated by a moisture meter. Although seed
is considered dry enough for storage at 10% moisture (Canadian
Grain Commission, Official Grain Grading Guide, effective
August 1990), the crop may be harvested at a higher seed
moisture if drying facilities are available. Usually,
early-sown flax is easier to thresh than late-sown flax
because it has a better chance to mature under drier
conditions.Keep the cutter bars of combines or swathers clean and
sharp to ensure a smooth cut and to prevent accumulation of
immature flax under the knife. Gumming of the cutting parts
can be reduced by frequent application of water or
kerosene.Chemical DesiccationChemical desiccation may be used to accelerate drying of
the crop and any weeds that may be present. It does not speed
crop maturity, but will reduce the time from maturity to
harvest. Potential advantages from this practice are:
- earlier harvesting; elimination of the need for
swathing; reduction in combining time; less wear and tear on machinery; cleaner seed;
- reduction or elimination of the
need for artificial
drying.
A desiccant may be applied after 75% of the bolls have
turned brown, which is the normal time of swathing. Studies at
Morden, Manitoba have shown that yields are reduced if
applications are made too early. For instance, swathing or
desiccating at the 25 to 50% brown boll stages, reduced yields
by an average of about 10% and 5% respectively, due to
premature termination of development of some of the seed.Desiccated flax should be harvested as soon as possible
after it is ready, to avoid capsule loss and weathering of the
seed. For up-to-date information refer to the latest
provincial recommendations, or consult your local agricultural
representative.ThreshingIt is important that combine adjustments are correct for
threshing flax. The seedcoat of flax is easily broken during
threshing, particularly if the cylinder speed is too high and
the seed is very dry. Damaged seed has reduced germination. If
the seed is to be used for planting, great care in threshing
is required. Yellow-seeded varieties are more susceptible to
seed damage because of their thinner seedcoat.
It may be necessary to adjust the combine from time to time
during the day depending on temperature, relative humidity and
the condition of the flax. The manual provided with the
combine should be consulted for correct settings. |
40. Sample of No. 1 Canada flax
seed (magnified)
41. Sample of No.2 Canada flax
seed. This seed shows the rime or scabbing which occurs in
years with a wet harvest. This condition is not considered
damage as long as the seed is otherwise sound.
42. Sample of heated to
binburnt flax seed. Dark tan, orange or dark brown pulp is
indicative of heat damage. Severely heated seeds are often
accompanied by a heated odor.
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Management of Straw
There are several methods of handling flax straw. Recent research
has indicated that none of the methods appear to affect the yield of
a succeeding crop of wheat. However, if the crop residues are
removed by burning or baling, it must be kept in mind that the soil
will become more vulnerable to erosion if summerfallow succeeds
flax. Therefore, an additional cereal crop following flax is
required to rebuild crop residues. Where continuous cropping is
practised, rebuilding crop residue becomes less of a concern.
Storage of Seed
The percentage of flax grading Canada #1 is frequently very high,
but dockage is often up to 10% (see Photos 40 and 41). Dockage can
be reduced by controlling broadleaf weeds as well as grassy weeds —
including volunteer cereals. If green weed seeds are present, they
may raise the moisture of the flax seeds enough to cause heating and
moulding. Removing this dockage before putting the flax into
long-term storage is advisable.Heated flax Stored flax requires more attention than does stored wheat.
Freshly harvested seed can maintain a high respiration rate for up
to six weeks before becoming dormant. This, coupled with mould
growth if the relative humidity of the air in the spaces between the
seeds rises above 70%, can lead to heating. Once flax starts heating
in a pocket, the heat will spread quickly - possibly throughout the
entire bin. For this reason, flax seed should be cooled down after
it is put into storage.
Flax seed can be safely stored at seed
moisture levels of 10% or lower. Tough flax contains from 10.1 to 13.5% moisture; damp flax is
over 13.5% moisture (Canadian Grain Commission, Official Grain
Grading Guide, effective August 1990). Each year some heated flax seed shows up in the delivery system
(see Photo 42). A wet harvest or an early fall frost will increase
the percentage of heated flax. If aeration equipment is not
available, bins of flax seed should be inspected frequently for
problem spots until the seed has cooled down. Flax seed has an
airflow resistance very similar to Polish-type canola (B.
campestris). Periodic checking is necessary to detect the
development of hot spots.As in other oilseeds and cereal grains, moisture migration will
occur in stored flax seed. Even though the seed is binned with
uniform moisture, high moisture spots can develop by moisture
migration. This usually happens in fall and early winter, although
it can also occur in the spring.Storage insects Stored flax seed is not troubled by storage insects as frequently
as cereal grains. Insects that can occur in stored flax are:
saw-toothed grain beetle, confused flour beetle, merchant grain
beetle and red flour beetle. Various fungus beetles and numerous
mites can be found in seed that remains tough to damp in storage.
Research in Manitoba has revealed that flax varieties vary in their
susceptibility to the saw-toothed grain beetle. The rusty grain
beetle occurs occasionally in carlots of flax. However, it is
suspected that this insect feeds on cereal admixtures in the
flax.The optimum temperature for rapid growth of insects is in the
range of 30° to 35°C (86° to 95°F). Their activity is greatly
retarded by temperature below 18°C (64°F). If the grain is cool and
dry, insects will generally not thrive. However, flax may be put
into storage at an acceptable moisture content and temperature, but
pockets of high moisture and temperature can develop later through
moisture movement on convection currents and heat production by
mould respiration which would encourage insect activity.SolinThe Canadian Grain Commission has established official grade
tables for solin which are different from those for flax. It is
important that admixtures of canola, mustard and especially flax are
avoided
during production, storage and transportation of solin.
There are three main differences between flax grade tables and solin
grade tables: For solin there are:
- tighter limits on damaged seed more categories for inseparable seed
- slightly tighter limits for heated seed.
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