Grain store preparation is one of the least glamorous jobs on an arable farm, although for one Oxfordshire grower it’s among the most crucial.
Investing significant time and money to produce tonnes of grain, only to see a proportion of it lost or downgraded to a lower-value specification due to poor grain store management is easily avoided.
Jim Calcutt, who grows about 440ha of wheat, oilseed rape and beans, likes to sell a proportion of his crop early, but also holds on to a large quantity in the hope of a higher price. It is therefore critical that he ensures his team makes a thorough job of cleaning the 4,000t of grain storage on his home farm at Hempton, near Banbury.
The key problems are insect pests such as grain weevils, grain beetles and grain borers. Rodents also need to be kept out of the store.
Mr Calcutt showed Farmers Weekly around his recently built 2,500t grain store with hardwood drying floor and gives some tips on reducing the risk of storage problems later in the year.
- Clean all the debris off walls, stanchions, fan tunnel and other surfaces from roof level. Cracks and ledges should be inspected and cleaned to ensure there is no debris or loose grain that can harbour insect populations after last year’s crop until the next harvest comes in.
- Once all unwanted debris is down at ground level, sweep up to one end of the store, collect and remove well away from the site for dumping or burning.
- Where drying floors are installed, ensure all cavities are completely empty of grain and dust and in areas such as these, use sticky traps to detect and monitor insect populations.
- Mr Calcutt has adapted a 400-litre Hardi ground sprayer to treat his stores. A telescopic lance with a wide-angle, high-output nozzle ensures rapid treatment and allows the operator to get to hard-to-reach places.
- Mr Calcutt uses the recommended label rate of K-Obiol (deltamethrin), which is applied until it runs from surfaces and gives two months’ protection against the key insect pests, except mites. Mites only thrive in humid conditions, so ensuring grain is dried and cooled correctly will keep them out. In his older store, Mr Calcutt increases the water rate to better penetrate dust.
- Good store hygiene is key to keeping out rodents such as rats and mice. Block potential access points and keep the area around the store clean and tidy. Only when activity is found – droppings, smearing and gnawing – should in-store bait be used. Remove bait when activity ceases to avoid non-target poisoning.
- If insects were a problem in the previous year, or insects are found in traps, an insecticide treatment should be used. Treat as soon as possible after the store is emptied and apply to all surfaces, including the roof space. If no insects are present, a thorough clean may be sufficient.
Avoid grain storage pitfalls
Monitoring and prevention of insect activity in store are key components of an integrated pest management (IPM) strategy, says Bayer CropScience’s manager for rural hygiene, Ken Black (pictured).
It’s estimated just two weevils in ideal conditions can multiply to 90 million in 12 months and have the potential to destroy 50t of grain, producing hotspots that attract secondary insects, and potentially fungus and moulds.
“Detecting and treating at an early stage is key as once grain is infested in store, the only option is to remove it and apply insecticide, to the grain itself. It’s expensive and a logistical nightmare,” says Mr Black.
There are limited options for chemical control of in-store insects, with other options including organophosphate insecticides which have a poor environmental and operator profile. There are also pirimiphos-methyl-containing smoke bombs.
“Smoke bombs offer good knockdown of insects, but they give no residual activity, so are a ‘quick fix’ and can allow insects to build up again,” says Mr Black.
Bayer’s K-Obiol offers two months’ residual protection and gives growers the chance to clean their stores early, apply the product and have peace of mind that insects will be controlled until grain is on its way into the store.
“It takes adult insects out, but where they have laid eggs, when those eggs hatch the larvae are also controlled. When it gets to harvest, there should be no insects, unless they come in from an external source,” says Mr Black.