SEVERAL new pests of germinating crops in southern and western regions are presenting challenges for growers.
Dr Paul Umina, from the University of Melbourne and Director of cesar, a science-based company working on sustainable pest control, said the shift was probably due to a complex interaction of several factors, including increased use of broad-spectrum insecticides, widespread adoption of stubble retention and minimal tillage, increased plantings of vulnerable crops such as canola, and drier conditions exacerbated by climate change.
He said reduced tillage had resulted in higher soil organic matter and moisture levels that favoured some pests, while increased use of chemistry has also changed pest populations.
"Increased insecticide use has wiped out some pests, but others, like Balaustium mite, have filled the gap like lucerne flea have increased in some regions due to increased use of synthetic pyrethroids (SPs)," Paul said.
In addition to mites and lucerne flea, there are a number of establishment pests in southern Australia, including weevils, wireworms, slugs and snails. More sporadic species, such as cutworm, also can be devastating - as experienced in south-eastern Australia last year.
Paul said a lot more insecticides were now used with broadacre crops, including canola, pulses and cereals.
"Canola is probably the crop that is more vulnerable to insect attack than other broadacre crops, so a lot of canola is now sown with seed treatments."
He said various pest species had developed resistance to different chemical classes.
"Some redlegged earth mite (RLEM) populations have evolved resistance to SPs and have a lower level of resistance to organophosphates.
"Green peach aphids, which are a vector for beet western yellow virus (BWYV), also have widespread resistance across a number of chemical classes in Australia, including SPs, organophosphates and pirimicarb.
Bryobia mite, also known as the 'clover mite', are prevalent in some situations and have an elevated tolerance to SPs higher than RLEM, but not as high as lucerne flea.
Balaustium mite are naturally more tolerant of insecticides than other broadacre mite pests. Moreover, this pest has increased in pest status in recent times and up until the recent registration of Pyrinex® Super insecticide from Adama Australia, there had been no product to control it in any broadacre crop.
We have really been grappling with effective control options for Balaustium for a number of years, so this is a good news story for the industry. We can now have an effective product that should control Balaustium mites when they reach damaging levels and require treatment."
cesar was involved with some of the early research and trial work that contributed to the development of Pyrinex Super.
The new insecticide also will address some of the issues with other species.
"It controls a multitude of pests that attack grain crops and pastures," Paul said.
However, he cautioned that all chemical products should be used as part of a broader, integrated pest management (IPM) strategy, rather than as "insurance" sprays. Before any decision to spray, growers should monitor crops carefully and assess the likely risk posed to a particular crop.
Pyrinex® Super is a unique, broad-spectrum insecticide featuring the two ingredients, bifenthrin and chlorpyrifos, that provide excellent knockdown and residual control (up to 58 days on some species) in winter crops and pastures, as well as in cotton, tomatoes and sugarcane.
Adama Australia Senior Product Manager Jock Leys said when applied to bare soil prior to seedling emergence, or onto pasture after direct drilling, Pyrinex® Super controls pests such as Bryobia mite, lucerne flea and even SP-resistant RLEM. When used early post-emergence on canola, it controls Balaustium mite, lucern flea, cutworm and other key pests.
Compatible with knockdown and residual herbicides, Pyrinex® Super has demonstrated excellent activity in trials.
While lower rates were effective in these trials against SP-resistant RLEM and Balaustium mite, a use rate of 1 litre per hectare has been registered for Balaustium mite to ensure consistent, long term control.
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