Summer is coming and with it are the pests—primarily caterpillars and aphids—to feed on your crops, cause yield loss, spread viruses and disease. It is tempting to grab a non-selective insect spray, like a synthetic pyrethroid or organophosphate, to kill just about anything crawling in it or about it. Before you do, remember not all insects in your crop are damaging. Some are beneficial and feed on the pests. So rather than turning to a non-selective spray, let Mother Natur do some of the work for you.
Integrated Pest Management (IPM) is about using cultural, biological, and selective chemical insecticide control to effectively control pests in crops. Agrichemicals, to be used sparingly and only when necessary, should be selective insecticide sprays, where possible, that are safe for beneficial insects.
Beneficial insects are split into two types:
- Predators - such as lacewings and ladybirds
- Parasitoids - which are mostly wasp species.
The predators eat the pests, with some consuming high levels of pest numbers. Parasitoids are the most important beneficial insects. These wasps lay their eggs in the pest, from which a small maggot hatches and consumers the host pest from the inside leaving only a cocoon of the host insect. Some species of parasitic wasp can lay over 600 eggs in a season to take out just as many pests.
Monitor your crops for both pest and predator. Generally, pests are the first to arrive, followed by the beneficial as they often use the pest to complete their life cycle.
Recent research on brassica crops in Canterbury by IPM Technologies' Dr Paul Horne found crops sprayed with a non-selective mid-season insecticide (like an organophosphate) saw a drastic reduction in pest and beneficial numbers. However, they can rapidly return because beneficial insects are slower to build in numbers.
TECH TIPS
- Choose wisely: careful paddock and cultivar selection helps reduce risk of some pests. Know which crops and areas on your farm are more susceptible to pest damage.
- Knowledge is power: being able to identify beneficial predators and parasitoids helps you target specific pests at the correct lifecycle stages.
- On watch: establish a plan to monitor both pests and beneficial insects.
- Control options: utilise cultural and biological control before considering a pesticide.
- Avoid broad-spectrum insecticides: once identifying your pests, only use products specific to that pest and have minimal impact on beneficial species.
- Conditions matter: recognise conditions leading to rapid increases in pest numbers.
- Crop monitoring: following crop establishment, regularly monitor for crop damage or aphid colonies.
This gap in your pest control leads to more damage and, potentially, requiring additional applications of spray. An IPM approach, where a selective insecticide targets only the pest species, the beneficial insects remain to prevent a return of pests and the need for additional spraying.
Farmers using an IPM programme save money, even when targeted sprays often are more expensive.
Integrated Pest Management | Dr Paul Horne of IPM Technologies
