Monitoring for canola insects is critical
From the December 2008 edition of Agriculture Today.
Table
- View the IPM canola combat table
Canola is one broadacre crop where available knowledge can help growers consider the merits of suppressing insect pests using integrated pest management (IPM) techniques.
"Canola hosts a range of economically important insect and mite pests that can affect yield potential if left unchecked, but with crops now maturing there are other factors to consider before rushing to spray," NSW Department of Primary Industries district agronomist at Cootamundra, Phil Bowden, said.
"These pests all have a wide range of naturally occurring biological controls that can often help keep their populations in check.
"Natural biological control agents include several predatory ladybeetles, hoverflies, lacewings, small parasitic wasps and fungal infections."
According to Mr Bowden, monitoring techniques could become part of an IPM program which could have many benefits, including maintaining biodiversity, reducing chemical use and minimising insecticide resistance levels.
Canola pests could occur simultaneously and control in the past had mainly involved spraying broad spectrum systemic chemicals.
"However, in many cases this is often unnecessary, so we need to monitor crops regularly, about twice a week at this time of year, to see if pest populations are above the damage thresholds and to see what beneficial insects are active," Mr Bowden said.
"Environmental conditions also play a major role in insect development cycles and need to be considered when controls are being planned.
"Many chemicals have specific requirements of temperature and humidity to work efficiently and heavy rain can wash pests off shoots as well, so it pays to keep a close watch on pest numbers.
"The key to maintaining control is regular monitoring, knowing what you are looking at, whether predator and parasite biocontrols are active and if pest numbers are likely to increase due to fresh new growth or plant stresses."
If a chemical was necessary, then a selective one for a specific pest was preferable, to preserve beneficial insects, which may also be helping to control other pest species.
Early in spring it was most important to preserve the beneficials, since their role was to keep pest numbers in check later on.
Mr Bowden said there was no point in spraying a broad spectrum insecticide early in the season as an insurance spray, or if pests had not reached economic damage thresholds.
"This can lead to greater pest problems later in the season because you will have destroyed all the natural enemies that would keep other pests at low levels," he said.
