On-farm grain storage has increased considerably in recent years, enhanced since the deregulation of the export wheat market, while farmer-retained seed also remains significant.
Bayer Product Manager Rod McLean said when you add up seed, fertilisers, chemicals and operating costs, growers were probably spending upwards of $300 per hectare to grow their crops, equating to about $120 per tonne of grain if they were achieving a yield of 2.5 t/ha. At a grain price of $250/t, that’s a gross margin of $130/t or $325/ha. Rod said protecting stored grain well could cost just $2.50-$2.80/t, or $6.25-$7/ha, however growers did not always apply the same approach to storing grain as they did to growing it. “When you are spending $120/t to get the grain into the bin, why skimp on another dollar or so, instead of maybe just a few cents, and risk insect infestations,’’ Rod said.
“If an infestation occurs, the grain would have to be shifted into a sealed silo and fumigated, which, with the handling and messing around, could cost $10/t. On the other hand, if it is sent off in the truck and rejected upon inspection, that could cost $30/t. And when there is plenty of grain about, customers can be choosy.’’ He said Australia’s winter grain crop was stored at a time when conditions were generally ideal for insect infestations. “Insects can be found in paddocks and if they go into a silo, they will multiply,’’ Rod said.
“In the case of the lesser grain borer, at 35 degrees, the life cycle is completed in four weeks. At 22 degrees, it is completed in seven weeks.’’ He said in relation to fumigation, the industry was concerned with poor practices, especially with phosphine. “This has been showing up as increasing resistance by lesser grain borer and other beetles to phosphine.’’ “In other areas of the world, there are already high levels of resistance to this fumigant. It would be a big problem for the Australian grain industry if the same levels were to eventuate here. “The main focus is to ensure phosphine is used in gas-tight, sealed silos, so minimum levels of the gas can be maintained over the required periods, which are measured in days – not hours. “Bombing with phosphine tablets just to kill adult insects as the grain is due to be sold is not good if the industry is going to have this as an effective product for the long term.’’ For market grain, Bayer recommends the use of its liquid grain protectant, K-Obiol EC, in combination with an organophosphate product like fenitrothion or chlorpyifos-methyl. “Fenitrothion and chlorpyifos-methyl are very cost-effective at around 50 cents and 80c/t respectively, but these products on their own have problems with lesser grain borer resistance and other resistance,’’ Rod said.
“K-Obiol, compared with other similar treatments, is more cost-effective at about $2/t, so why take a risk saving this when you could end up having to retreat grain or have a truck load rejected.’’ In combination, the K-Obiol controls the lesser grain borer, while the organophosphate product better targets rice and granary weevils, which have shown some tolerance of K-Obiol. “Used in combination, fenitrothion and K-Obiol provide the best protectant against insect attack,’’ Rod said. Containing deltamethrin, K-Obiol can be used on all, uninfested cereal grains, including malting barley, sorghum, rice and maize, in sealed and unsealed storage, and it is active for up to nine months.
Rod said with the combination using two insecticide modes of action, resistance was unlikely to develop. “We also recommend rotating K-Obiol with a Group 5 insecticide on an annual basis to further reduce the likelihood of resistance.’’
It is available to approved bulk handlers only in Western Australia. In other states, K-Obiol users complete a simple online training program prior to use of the product and retail distributors are also audited as part of the product stewardship program.
“The training helps to ensure there is never the risk of over-treating and exceeding grain residue levels,’’ Rod said. He said another good practice to ensure grain was sold in the best possible condition was to clean out silos, headers, augers and grain handling equipment, removing pockets of grain where insects could be harboured.
For farmer-retained cereal seed, Bayer’s popular and economical seed treatment insecticide, Gaucho 600, provides protection against a range of insect pests. Containing 600 g/L of imidacloprid, it protects against granary weevil, Indian meal moth, lesser grain borer, rice weevil, rust-red flour beetle, sawtoothed grain beetle and tropical warehouse moth. Plus growers also get the benefit of effective control of a range of aphids, including Russian wheat aphid, and the prevention of barley yellow dwarf virus spreading during early crop establishment.
Bayer Broadacre and SeedGrowth Brand Manager Nick Moses said an application of 240 mL/100 kg of seed with Gaucho 600 would provide good protection against stored grain pests through to aphids early the next season in cereal crops.