Farm Table says:
Reducing Insecticide Use in Broad-Acre Grains Production: An Australian Study
What is the problem?
There is increasing concern over insecticide use regarding both farmer and consumer safety, as well as pests developing resistances to insecticides. Pest variety and numbers have been shown to fluctuate over time, so a set spray regime can be costly and unnecessary.
The aim of this study was to measure the impact of different pest management approaches in wheat and canola crops across southern Australia. The results aim to highlight situations where growers could reduce pesticide inputs without impacting profitability.
What did the research involve?
The researchers from the University of Western Australia gained permission from 5 commercial farms (2 in WA, 1 each in NSW, VIC and SA) to perform these field trials over 2 growing seasons. Each farm had Control plots, conventional/high input plots (following the local regions common insecticide spray regime), and low input plots that used pest monitoring and selective sprays. They measured all 3 plot types by:
- insect counts,
- plant chewing and sucking damage,
- final yield, and
- pest control costs.
What were the key findings?
- Insect abundance: The high input fields showed the greatest reduction in numbers of both pest and beneficial insects over time. The number of pests and beneficials in the low input and control plots maintained moderate levels.
- Crop Damage: Many of the trials showed similar levels of plant damage across the three pest management approaches.
- Crop Yield: Statistical analysis from across the experiment showed no link between increased insecticide input and greater yield. In canola the highest yields were achieved when insecticide treated seeds were used. The wheat crop yields suggest that pest management approach and additional insecticide inputs had insignificant impact on crop yield.
- Pest control costs: The conventional/high input plots incurred the greatest costs on average. Although one low input crop was the most expensive due to a pest outbreak requiring the use of Bt spray, which is a pest specific spray that doesn’t harm other insects.
Overall there were no significant effects of different pest management strategies. Insecticide use did reduce pest numbers, but this did not translate to an increased yield. Likewise, the control plots with clear evidence of feeding did not have significantly lower yields, and in some cases, greater average yields. Low input options also have the potential to be cheaper but require greater knowledge to implement successfully.
This paper was summarised by Mia Courtney (Agricultural Sciences Student – La Trobe University) and reviewed by Nickala Best (PhD Student – La Trobe University). Learn more about Mia and Nickala here.