Understand the potential yield losses associated with false wireworm feeding damage.
- Fifteen adults per square metre in summer may produce over 1500 larvae, which is sufficient to damage most canola crops at the seedling stage, if seeding coincides with later instar stages. The adults chew on seedlings at or above ground level, ring-barking or completely cutting stems. Larvae bore into germinating seed and chew on seedling roots and shoots. Larvae can cause substantial economic losses.
Assess the cost and benefits of removing surface plant material prior to seeding.
- The removal of surface plant material (stubble), where it is considered to be a suitable practice, will reduce or eliminate this pest. This may be achieved through cutting and baling, grazing or burning.
Compare the costs, benefits and risks of each management option against doing nothing or delaying treatment.
- What are the likely outcomes of each management option? When the result of treatment is unknown consider the most likely (expected), as well as the worst and best results from each treatment option.
- When calculating the cost of non-treatment assess the potential yield losses.
- The effectiveness of insecticide applications is poor if there is heavy stubble on soil surface.
- Compare the costs of alternative options ensuring that you allow for the possibility of further treatment.
- Selection of insecticide may be influenced by the opportunities to control other insects.
- If applying insecticide at the same time you would with other treatments, only assess the actual cost of adding the extra treatment to the operation, i.e. the total cost of going over the paddock is not included as it would have been incurred anyway. The additional (marginal) cost is simply the direct cost of the insecticide and any additional time needed to prepare and apply it.
- Consider the potential costs of further treatment.
- Consider costs and benefits for both ground and aerial application methods.
- Consider choosing a treatment option where the expected return is sufficient to offset its risk of the treatment. We all have different attitudes to risk when making decisions. The probability (risk) of outcomes can be affected in terms of responsiveness (efficacy), application rates, products, application methods and climatic conditions. The economic calculator can assist with this decision.
Ignore all previous treatment costs when assessing current management options.
- Costs associated with previous treatments are ‘sunk costs’ and should be ignored as they cannot be recovered and will not affect the economic outcome of taking various courses of action from this point forward, i.e. even if the current treatment results in the crop not breaking even, provided the additional benefit of undertaking the treatment exceeds the cost of treatment, then the economic return will still be better than doing nothing about it.
Include a resistance management strategy into your spray program.
- Include a resistance management strategy into your spray program to reduce the chance of false wireworms and other non-target pests becoming resistant. If monitoring indicates the need to spray, then insecticide choice and rotation of chemical groups needs to be considered, along with appropriate spray application.
To assist in assessing the economic risk and financial costs associated with various treatment strategies go to MyEconomicTool