Before we moved into using IPM we had a set insecticide spray program for control of insect pests. We used broad-spectrum insecticides, which killed all insects so in theory we should have had clean crops with no insects.
In the 1990’s we had a problem with two-spotted mite in our leek and parsnip crops. We had been rotating our chemicals making sure that we were using different chemical groups so as to not cause resistance to one chemical but this was not working. The two-spotted mite had built up resistance to whatever we hit them with and were building in numbers.
Not liking the idea of continuous use of dangerous chemicals (for health reasons) and having no success in controlling our pests, we needed an alternative. A fellow grower (Tom Schreurs of J. & J.M. Schreurs & Sons) advised us to talk to Dr Paul Horne of IPM Technologies. Dr Paul Horne came out to have a look at the problems we were having with the two-spotted mite and immediately advised us to stop spraying. This was unprecedented advice when for decades we had relied on spraying chemicals to control pests to then not spray at all. Paul then went on to explain how a predator mite called persimilis actually fed on two-spotted mite and by allowing the persimilis to live in the crop they would then control the two-spotted mite.
Being a bit sceptical we tried a small-scale experiment (in a fish tank) to see what would happen. By 18 days the persimilis had eaten all the two-spotted mite. This then brought us on to try this out in the field on our leek crop. We closely monitored the crop, a little nervously, but after 4 weeks there was not one two-spotted mite to be found in the leek crop. This made us realise that there was more to pest management than just spraying chemicals. If we could understand more about what is happening in the insect world we may then possibly understand how to control them naturally.
With this first experience with our leek crop we then built up enough courage and experience to then use IPM in all our crops. By 2001 we had all of our crops pests being controlled using IPM.
We feel there are many benefits to using IPM. As we are no longer using broad-spectrum insecticides it is much safer for the people involved with pest management, safer also for the environment, protecting birds, waterways and other insect species from dangerous chemicals. For the consumer this has the added benefit of knowing that there will be no insecticide residues on produce that may be harmful.
Using IPM means that we spend more time in the crop monitoring insects rather than sitting in the spray tractor, which then allows us to be in more contact with the crop and able to detect other problems such as disease or weeds before they become serious problems.
IPM is a long-term sustainable way of controlling pests. Since using IPM it has led us to have a greater understanding of how nature works and of how our actions on the farm impact on the environment around. We have a much broader view on what our farm was and has led us to start our own sustainability initiatives.
To encourage more beneficial insects onto our farm we are planting more native trees and shrubs that flower during different times of the year so as some insect species can use these as a food source between crops. We have also started growing crops such as rye corn in ground side by side with lettuce. The rye corn attracts grass feeding aphids that provide food for a large number of predator insects, which then breed up, and move into the lettuce crop controlling aphids such as currant-lettuce aphid.
One of the problems that we have had in using IPM is that we cannot guarantee that our entire product is insect free. Using beneficial insects to control insects means of course that we will have insects present throughout crop production. Despite having very thorough washing systems in place before any produce is packed and dispatched there may still be some insects present in some produce.
It has been a challenge dealing with some of our customers, in particular with product being exported, to be able to meet the criteria of no presence of insects. We feel that with more awareness of what IPM is, people will then understand that finding a ladybird or a brown lacewing in your lettuce is not a bad thing and in fact people may become more comfortable in finding this in their produce knowing that there are no chemical residues that inhibit any insect activity.
Disease control comes hand in hand with IPM. We have moved away from using most chemicals for disease control as a lot of them also interfere with insect activity and can harm beneficial insects that we are promoting in the crops so here again we look for alternatives.
One of the most simple things we ensure is proper crop rotation so that the same species of vegetable is not grown on one particular paddock over and over again. This will assist in breaking the chain of disease build up.
Another more exciting disease control method we are using is the use of certain cover crops that we will grow and then be incorporated into the soil. The decomposing plant matter will act as a bio-fumigant in the soil helping to control a variety of insect pests and diseases. One of these crops is mustard, which not only acts as a bio-fumigant, but also adds to organic matter in the soil helping to build a more fertile well structured soil.