WITH harvest underway – or just around the corner – graingrowers in northwest Victoria and the Mallee need to be aware of the greater choice they have for stored grain protectants for cereals.
But with choice can come confusion.
However, grain storage specialist Chris Warrick says there are two easy steps in selecting an appropriate protectant.
As leader of the GRDC’s grain storage extension project, he 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,” Chris explains.
He says the first step is to choose a Spinosad or Deltamethrin based stored-grain protectant and ideally rotate it 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,” Chris says.
“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, Chris 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.”
The 1800 WEEVIL hotline (1800 933 845) also gives growers a national team of grain storage specialists to call for information about grain storage management.
