When the Russian wheat aphid first arrived in Australia in May, Australia’s grain industry went into a panic because the insect was potentially devastating for cereal crops.
But no one could have predicted the record rainfall that hit parts of South-Eastern Australia, which has virtually wiped out the exotic pest.
South Australian Government principal entomologist Greg Baker said the aphids were unlikely to affect this year’s harvest because most of the insects were drowning in watery mud.
“In general terms, I think most crops are likely not to experience further infestation levels”, he said.
Last month, Baker’s research team was counting about 100 aphids per tiller of wheat in three research zones in South Australia.
In those same areas, the researchers are now seeing numbers closer to one and sometimes zero aphids per tiller.
“As we understand it, the observations that we’ve been making recently in South Australia are being mirrored in Victoria and southern New South Wales”, Baker said. “In the absence of those rains, we would have seen numbers increase – so quite dramatic effects from the rain”.
While it is good news for grain growers this harvest, Baker said the Russian wheat aphid was here to stay in Australia.
“There’s going to be an ongoing need for us to continue to learn more about this aphid”, he said. “We’ve dodged a bit of a bullet in terms of how this spring goes. But there’s no reason to expect that Russian wheat aphid isn’t here to stay”.
Entomologists also have noticed there has been quite a lot of fungal infection of aphids in cereal crops.
The recent record rainfall that has helped kill off the Russian wheat aphid has also seen an increase in the separate foliar fungal diseases in crops. This increase has caused a huge spike in fungicides.
Sales representative Stephen Lyons from Crop Smart, an agriculture chemical distributor in western Victoria, said the wet weather was causing such strong demand for fungicide, his company was having to air freight product from China, costing producers triple their normal freight cost.
“There’s a lot of demand coming from all states really, as high up as Queensland, as far south as South Australia”, he said. “It’s not just one area that doesn’t have it. It’s right across. You could never have forecast for the amount to be used that has been used”.
Lyons said his company had now doubled the price of fungicide to bring it in line with market demands. (ABC/Business World Magazine)