The last season was exceptionally hot and dry – conditions which favour pests such as two-spotted mite and western flower thrips. Did that mean growers had to spray more, and how did IPM perform?
Certainly, some growers had to spray more, but a couple of orchards in the Goulburn Valley -Geoffrey Thompson and Plunkett Orchards – that had made good progress with IPM, either sprayed less or not at all for thrips and mites. This is not a coincidence – it is the result of a lot of work going into control of all pests in a sustainable way and, in particular, good cultural controls.
IPM means using all control options in a compatible way and the only control options are biological controls (insects and mites that eat the pests), cultural controls (management methods including inter-row cover crops and canopy structure and height) and insecticides and miticides.
While the importance of avoiding disruptive insecticides is well understood, just how much impact beneficial species can have is often not understood until the total control of secondary pests is seen. Secondary pests are those largely caused by insecticide applications that kill the beneficial species that control them. In orchards, secondary pests include two-spotted mite, western flower thrips, woolly apple aphid and mealybugs. It should be entirely possible to control these pests without insecticides or miticides.
This might seem to be a big call, but is very achievable, as shown by Jason Shields at Plunketts even under last season’s extreme hot and dry conditions.
Why use IPM?
IPM is a concept that has been around for a long time. While it has been easier to spray pests, many growers have chosen to do that. But when pesticides are withdrawn or when pests become resistant to pesticides that option may be lost. Market requirements may also demand that certain products are not used.
The main reason that growers should consider IPM is because of better control of all pests and no longer having to spray at all for some pests that at present are considered really serious and difficult to control with pesticides. Recent experiences at Plunkett and Geoffrey Thomson should encourage growers and show that IPM can deliver great results.
The main concept to understand is that we are dealing with multiple generations of some pests and beneficial species and that these interact over a long period of time. When we see problems with pests in January or February, we are seeing the result of what has been building for the last five months. The problem did not just appear in February. Similarly, when growers did not have to spray for mites in February, that is also the result of management of the pests over the preceding months. In the case of woolly apple aphid, it is the result of multiple years of effort.
There are examples of individual Australian orchards adopting IPM and minimising insecticide and miticide use, such as those mentioned here. However, if anyone is interested in the New Zealand experience, there is total adoption of IPM. This has been described in a recent book called Farewell Silent Spring by Howard Wearing that documents the change from use of broad-spectrum insecticides decades ago to the current state of minimal insecticide and miticide use. While Australian growing conditions are different to those in New Zealand, I am optimistic that in the near future Australian production will also be totally IPM. This is something that should be a target because the bottom line is – IPM delivers better results for growers.
To practice IPM, there is a need for knowledge of pesticides and their impact on beneficial species, and of cultural options and recognition of beneficial species. However, all this information is accessible. Anyone interested in trialling IPM is welcome to contact Dr Paul Horne or Jessica Page from IPM Technologies.
About the author:
Dr Paul Horne, IPM Technologies.