Controlling aphids in broadacre crops is not primarily about limiting feeding damage. The greatest threat is that the aphids will infect the crops with a devastating disease.
Green peach aphid (GPA), for instance, generally causes very little feeding damage in canola crops, but is a key vector for the transmission of Turnip Yellows Virus (TuYV). TuYV can cause yield losses of up to 50% if the crop is infected before bolting.
Beet western yellows virus, cauliflower mosaic virus, cucumber mosaic virus and turnip mosaic virus are also widespread and damaging diseases that GPA can spread as they feed on canola.
Timing is a key factor in limiting the damage from infection in a number of ways. The crop and spray timing issues are relatively straightforward:
- The potential for yield loss is much greater in crops that are infected early, so careful monitoring is highly recommended. Inspection at budding and early flowering will often reveal aphids amongst the buds and flowering heads. The crop can then be sprayed before dense clusters from and it becomes harder to get spray coverage of all the aphids.
- In general, aphids should be sprayed when 20% of plants are infested with colonies of aphids. As always with insects, applications early in an infestation are more likely to achieve quick control. In the case of aphids, early intervention also minimises the opportunity for disease transmission.
Now an innovative option from BASF has made an extra timing advantage available to growers. Versys® Insecticide, which is already widely used by Australian fruit and vegetable growers, has been registered to control aphids in canola, wheat and barley.
One of the product’s key benefits is that it can stop affected aphids feeding within 15 minutes. That is much faster than other insecticides, greatly limiting the aphids’ opportunity to spread infection. The SARDI PestNote on GPA reports that they need 15–30 minutes of feeding to infect a plant.
The reason Versys can stop feeding so quickly is that its distinctive mode of action disrupts the aphids’ nervous system and disturbs its hearing and balancing, inducing a ‘dance’: constant jittery movements that prevent feeding.
This effect is sufficiently different to place Versys in a mode-of-action sub-group of its own: Group 9D. So adding it to the rotation will strengthen growers’ resistance management programs.
Using Versys will also enhance IPM programs and help minimise the environmental impact of insecticide use. Its mode of action is particularly efficient, with excellent translaminar and acropetal mobility to reach the underside of sprayed leaves, and is effective at low rates. The formulation has low toxicity, so it poses very little risk to pollinators and is compatible with the common beneficial arthropods including predatory mites.
Versys can be used twice with a spray interval of 14 days if aphid pressure requires it, but the BASF technical experts emphasise the importance of a pro-active approach that ensures early intervention with complementary management initiatives.
They recommend:
- controlling summer weeds to prevent a green bridge, then
- monitoring canola crops at 5 points in each paddock with 20 plants at each point,
- backing up Versys with biological controls like hoverflies, lacewings, ladybirds and damsel bugs, and (of course)
- rotating between chemical groups if more than 2 sprays are required.
While Versys also now provides an innovative control solution in wheat and barley crops, the BASF team is already seeing that most of its early broadacre use will be in canola, where it can probably provide the biggest return on investment.
“There’s a clear need for a solution like Versys in canola,” says BASF Canola and Pulses Protection Portfolio Manager Shannon Altomare. “It will deliver great value by allowing growers to improve pest and disease control at the same time as they’re managing resistance issues and reducing the impact on the environment.
“Versys is part of a range of BASF initiatives that will make growers less reliant on older chemistry while also extending the life of those established solutions. The release of LibertyLink® canola varieties provides the option of using glufosinate to enhance in-crop weed control. And next year we’re scheduled to release an innovative fungicide that will give growers another premium quality option to tackle disease control.
“So the immediate benefit of using Versys to get really rapid and effective aphid control is really only the start of the story.”