Gerri the NVT Guru explains how to manage Russian wheat aphid in South Australia and Victoria using the GRC FIGHT strategy: find, identify, apply thresholds, and enact management. Spray only when 20% of tillers are infected at tillering, or 10% during spring. Use selective insecticides like chlorpyrifos or pymetrozine instead of broad-spectrum sprays.
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Integrated Pest Management or IPM is all about managing and preventing crop pests through a mix of chemical, biological and cultural controls. IPM aims to stop pests from getting to economically damaging levels, but also to provide a long term solution for crop pest incursions. IPM is not about abandoning chemical use altogether. Rather it aims to reduce our reliance on pesticides as the sole means of pest control on farm. We know that when we rely on pesticides too much we get problems with resistance and eventual control failures down the track. There are steps growers can take to adopt IPM principles. The first one is monitoring. Routine monitoring is really important in any IPM program. This involves monitoring of both pest and beneficial species. To make the most out of monitoring, the next step is to get a positive identification of your pest or beneficial species. In addition to industry specialists that can help you out with this, there are resources available such as the GRDC View Guide. Another IPM principle that growers can adopt is spraying only if necessary. Avoid prophylactic spraying or spraying just in case. This will only harm your beneficials and make your cropping system less resilient to secondary pest incursions that could happen down the track. If spraying is necessary, choose selective over broad spectrum insecticides where possible. And finally growers can incorporate control methods. This can include making management decisions around crop rotation, time of sowing, grazing, tillage or cultivation that make the environment less favourable to pests.
So we know Russian wheat aphid are quite widely distributed across South Australia and also in parts of Western Victoria, particularly in the Wimmera and the Mallee. We've found commonalities around Greenbridge, so where there's been volunteer cereals and grasses in paddocks over summer, late herbicide applications and early sowing. As we head into spring we're leading into a relatively so called high risk period for Russian wheat aphid infestations which is typically from around stem elongation through to the soft dough stage. And based on overseas experience this would be potentially the period when the highest impacts on yield are likely to be seen. So the FIGHT strategy is a GRC initiative which has four steps to help advise growers and advisers around how to manage Russian wheat aphid going forwards. The first step is around how to find and locate Russian wheat aphid within cereal paddocks. The second step is to positively identify Russian wheat aphid through consultation with an industry specialist. The next step is to adopt a threshold approach based on overseas literature. There are two thresholds that have been advised for growers in Australia up until the tillering stage, there's an economic threshold of when chemical sprays should be applied, which is at about 20% of tillers infected with Russian wheat aphid. As we step into that higher risk period in spring, that threshold is reduced to about 10% of tillers showing signs of infection of Russian wheat aphid. The fourth step is around enacting management and currently there are two chemicals that have been registered via APVMA under emergency use permits. Those two products are clopyrifos and pyramicarb. Both of those products have been shown to work very effectively against Russian wheat aphid, both in South Australia and in Victoria. There are numerous benefits to integrated pest management, such as conserving beneficials by the judicious use of chemicals and only applying chemicals whenever needed. There are also benefits to the environment and importantly, IPM will also extend the life of agrochemicals that we currently have at our disposal.
