Growers now have greater choice of stored grain protectants for cereals this harvest, but with choice can come confusion. Grain storage specialist Chris Warrick says, “There are two easy steps in selecting an appropriate protectant.”
Leader of the Grains Research and Development Corporation’s (GRDC), Grain Storage Extension Project, Mr Warrick encourages growers to look at the product’s active ingredients to simplify the choice.
“There are several new brands and product names available this year so the choice can be overwhelming, until you look at the product’s active ingredients to simplify it,” Mr Warrick says.
According to Mr Warrick, the first step is to choose a Spinosad or Deltamethrin based stored grain protectant and rotate ideally every year to prevent resistance. Deltamethrin or Spinosad (which will have S-Methoprene included) provide affective protection against four of the five common grain storage pests.
“This choice is easy as it’s simply a matter of rotating to reduce the risk of insect resistance developing in the same way we rotate herbicide Groups used in the paddock for weed control.”
The second step is to choose a mixing partner to include protection against the rice weevil. The choice will be stored grain protectants with either Fenitrothion or Chlorpyrifos-methyl as the base active ingredient.
“This choice will come down to grain type, withholding period and market acceptance. Fenitrothion is registered for use on malt barley, rice and maize but has a 90-day withholding period when applied at the higher nine-month protection rate. Chlorpyrifos-methyl has no withholding period but is accepted by fewer international markets.
“Some brands now provide pre-mixed or packaged products for convenience, so check the product’s active ingredients to understand what’s included in the mix.
“For complete protection pre-mixed or products selected for mixing together must include either Spinosad or Deltamethrin and Fenitrothion or Chlorpyrifos-methyl, noting delivery restrictions apply to the latter two actives.”
Before using any grain protectants, Mr Warrick insists growers read and follow the label directions, use only on cereal grains and consult the intended grain buyer to ensure the market accepts the selected products.
“Each product can only be applied once to a parcel of grain and accurate application is essential to avoid breaching Maximum Residue Limits (MRL). Expect to complete a short stewardship or online course before being able to purchase protectants, followed by commodity vendor declarations before selling the grain.”
GRDC Grower Relations Manager Graeme Sandral says observing MRLs are a particularly important consideration.
“It’s important to remember as an industry we want to provide the best food possible for kitchen tables around the world and that means maintaining grain quality, ensuring MRLs are strictly observed and maximising the usefulness of products into the future,” he says.
When it comes to non-gas tight sealable storage, Mr Warrick encourages growers to use protectors.
“Protectants are a great option for cereals going into non gas-tight sealable storage such as sheds, bunkers and silos which don’t pass a three-minute half-life pressure-test, Mr Warrick says.
“We don’t have the option to fumigate in non-gas-tight storages and the available spray on products are protectants to prevent an insect infestation, they won’t work as a knock down.
“Hygiene and structural treatments, aeration cooling, protectants and regular monitoring are all pest prevention tools to reduce the likelihood of issues in stored grain. Combining prevention tools gives the chemistry in protectants the best chance of having full and lasting effect.”
Thanks to GRDC’s investment in the 1800 WEEVIL hotline (1800 933 845), growers have a national team of grain storage specialists to call for information about grain storage management.
There is more grain being stored on farm than ever before, and the various types of storage require a planned approach to mitigate potential issues.
“The team much prefer a phone call to help growers plan their grain storage management than the phone call when there’s an issue and options are limited,” Mr Warrick says.
For more information, view Chris Warrick's video on Grain storage protectant choice for 2023.