The “4T” approach to insects in the vegetable garden and fruit orchard is a decision-making tool and it goes something like this:
1) Know your target, 2) Figure out your timing, 3) Use the right tool, and 4) Adjust your technique to the given situation so you are optimizing the chance that your tool will work.
Target. Timing. Tool. Technique. The Four Ts.
The 4T approach is not as simple as going to your store and asking what spray works for what insect. The contact insecticide spray you buy to fight squash vine borer will not work as effectively if, for example, the eggs have hatched seven days ago and your target (e.g., young squash vine borer caterpillars) have already burrowed into the vine. Likewise, the plain insectcidal soap may not work as well against flea beetles as the insecticidal soap that contains neem tree oil.
Very simply, the 4T approach is a way of organizing the decisions you make in terms of the products you choose to use so you also have a plan in place to use them properly. Planning and preparation are key to responding effectively to the insects in your garden.
The 4T approach asks the grower to think in advance of the growing season about the insects that will likely become an issue in the garden area. By thinking ahead, say in late April instead of late May or early June…and tracking the development of insects using insect degree days…the grower will be more aware of what insect and life stage to look for and when to look for it…and more prepared to respond effectively using the right tools in the right way.
The Four T approach goes like this:
- Target. Before you do anything, you need to know your target. Target means basically “what species of insect” and “what life cycle stage is the most vulnerable”.
- Timing. The next thing you need to do is find out approximately when your insect will be emerging, and which stage of its life cycle you are going to target. Timing has a lot to do with insect degree days.
- Tools. Once you know your target and know the stage you’re focusing on, you select the appropriate tool. This basically means if you are an organic grower, you need to find out which pesticides or other tools are allowed for organic food production. If you are not an organic grower, but want to use low-risk pesticides that have short residual times and are compatible with human food consumption, you still need to find out which tools meet your needs and reflect your values and/or the values of your customers.
- Technique. Finally, each tool has a way of using it that will be more or less effective. Insecticidal soap, for example, can be sprayed on the underside of leaves for better control of aphids, scales, and plant-feeding mites. Insecticidal soap with neem oil might be even more effective because of its repellent and antifeedant properties.
The 4Ts are covered in more detail during the IPM Workshops for the Permaculture Research Institute Cold Climate and other workshops for gardening groups.Neil Cunningham firstname.lastname@example.org March 2012 (updated January 2013)