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The process of leveling the grain requires the judicious use of the grain auger and
a brief period of physical labor using a grain shovel. The level surface is well
suited for monitoring with pitfall traps, and for the proper application of fumigants.
MONITORING Pest monitoring is an
important component in the IPM post-harvest practice for stored grain. Inspections
should be done frequently, especially after first storage. Initially, grain is inspected
for insects weekly until the baseline insect numbers are known. Then the grain is
monitored every 2-3 weeks during throughout the autumn until the grain is cooled
to 50-55°F or below, and monitored monthly for the remainder of the storage
period.
Grain managers should carefully monitor the following:
? Grain quality ? Grain temperature Figure 1.14 ? Insects and insect density ? Hot
spots ? mold growth ? Any “off odor” Temperatures below 60°F prevent insect
activities, while higher temperatures allow for increased insect growth and
breeding.
Many storage structures are equipped with temperature sensors that provide the
temperature of the grain through the grain mass. The sensors are place on
permanent cables that are suspended from the roof of the storage bin. Three are
midway between the center and the wall, and one is very near the center (Figure
1.16). Information is transmitted for each thermocouple to a reading device that
helps grain managers record temperature over time. More than a five-degree rise
(>50 F) recorded by one of the thermocouples over a two-week period indicates a
pest or moisture problem exists in that location. Monitoring also detects changes in
grain temperature during aeration or seasonal temperature fluctuations. Temperature
of the stored grain in bins without temperature monitoring devices can be
monitored by a thermometer mounted on a probe and inserted into the grain mass,
or simply by inserting one’s arm into the top layer of the grain mass.
Frequent
grain sampling from several locations throughout the storage structure provides
grain managers with the status of insects and grain quality. Initial sampling should
be done at least weekly until the history of the grain has been clarified. In many
warmer locations, samples are collected from standing grain using either a deep bin
cup or a grain trier (Figure 1.17). An alternative that works quite well is to use
pitfall probe traps that remain in the grain (Figure 1.18). These traps are placed
just below the grain surface or probed into the grain. With Montana’s,
comparatively low insect numbers, these traps can be serviced weekly to readily
provide similar information to sampling.
Note that the traps are more sensitive
than sampling, so the numbers will appear greater than from sampling.
Nonetheless, the basic approach remains the same. Numbers and species of
insects are recorded to assess a monthly pattern. The presence of insects in dry
whole grain is an indication of future economic loss (in terms of live insects at
time of sale). The presence of IDK-causing insects will result in discounts at the
time of sale. A moldy appearance, dampness, off-odor, presence of IDK, and high
moisture levels can also indicate insect problems. Consistent findings of internal
feeders and IDK call for fumigation to protect grain value. AERATION Aeration is
used to dry and cool newly-stored grain. It is also used to prevent moisture
migration when ambient temperatures drop below that of the grain temperature.
Moisture migration occurs when outdoor temperatures decline during the fall and
winter. Grain and air temperatures near the bin walls also drop. The insulating
characteristics of grain prevent temperatures in the center of the grain mass from
falling as rapidly. Cooling air near the bin wall makes this air more denser
(heavier), and it settles toward the bin floor. At the same time, warmer air near
the center of the bin floor is less dense (lighter). This air, which is displaced by
the cooler air, rises through the center of the bin, absorbing small amounts of
moisture from the surrounding grain as it rises. Grain near the top of the grain
mass, like that near the outer walls, is cooler than the rising air. As the warm air
rises through the cooer grain and is cooled by it, moisture condenses from the air
onto the grain. This moisture migration produces wetting and crusting of surface
- 397 -
a brief period of physical labor using a grain shovel. The level surface is well
suited for monitoring with pitfall traps, and for the proper application of fumigants.
MONITORING Pest monitoring is an
important component in the IPM post-harvest practice for stored grain. Inspections
should be done frequently, especially after first storage. Initially, grain is inspected
for insects weekly until the baseline insect numbers are known. Then the grain is
monitored every 2-3 weeks during throughout the autumn until the grain is cooled
to 50-55°F or below, and monitored monthly for the remainder of the storage
period.
Grain managers should carefully monitor the following:
? Grain quality ? Grain temperature Figure 1.14 ? Insects and insect density ? Hot
spots ? mold growth ? Any “off odor” Temperatures below 60°F prevent insect
activities, while higher temperatures allow for increased insect growth and
breeding.
Many storage structures are equipped with temperature sensors that provide the
temperature of the grain through the grain mass. The sensors are place on
permanent cables that are suspended from the roof of the storage bin. Three are
midway between the center and the wall, and one is very near the center (Figure
1.16). Information is transmitted for each thermocouple to a reading device that
helps grain managers record temperature over time. More than a five-degree rise
(>50 F) recorded by one of the thermocouples over a two-week period indicates a
pest or moisture problem exists in that location. Monitoring also detects changes in
grain temperature during aeration or seasonal temperature fluctuations. Temperature
of the stored grain in bins without temperature monitoring devices can be
monitored by a thermometer mounted on a probe and inserted into the grain mass,
or simply by inserting one’s arm into the top layer of the grain mass.
Frequent
grain sampling from several locations throughout the storage structure provides
grain managers with the status of insects and grain quality. Initial sampling should
be done at least weekly until the history of the grain has been clarified. In many
warmer locations, samples are collected from standing grain using either a deep bin
cup or a grain trier (Figure 1.17). An alternative that works quite well is to use
pitfall probe traps that remain in the grain (Figure 1.18). These traps are placed
just below the grain surface or probed into the grain. With Montana’s,
comparatively low insect numbers, these traps can be serviced weekly to readily
provide similar information to sampling.
Note that the traps are more sensitive
than sampling, so the numbers will appear greater than from sampling.
Nonetheless, the basic approach remains the same. Numbers and species of
insects are recorded to assess a monthly pattern. The presence of insects in dry
whole grain is an indication of future economic loss (in terms of live insects at
time of sale). The presence of IDK-causing insects will result in discounts at the
time of sale. A moldy appearance, dampness, off-odor, presence of IDK, and high
moisture levels can also indicate insect problems. Consistent findings of internal
feeders and IDK call for fumigation to protect grain value. AERATION Aeration is
used to dry and cool newly-stored grain. It is also used to prevent moisture
migration when ambient temperatures drop below that of the grain temperature.
Moisture migration occurs when outdoor temperatures decline during the fall and
winter. Grain and air temperatures near the bin walls also drop. The insulating
characteristics of grain prevent temperatures in the center of the grain mass from
falling as rapidly. Cooling air near the bin wall makes this air more denser
(heavier), and it settles toward the bin floor. At the same time, warmer air near
the center of the bin floor is less dense (lighter). This air, which is displaced by
the cooler air, rises through the center of the bin, absorbing small amounts of
moisture from the surrounding grain as it rises. Grain near the top of the grain
mass, like that near the outer walls, is cooler than the rising air. As the warm air
rises through the cooer grain and is cooled by it, moisture condenses from the air
onto the grain. This moisture migration produces wetting and crusting of surface
- 397 -
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