Organic Pest Management

Most growers are aware that organic food products are becoming more common in the marketplace. Currently organic food sales are around 1% of the total, which is not a large marketshare, but it is growing at about 10-20% per year. Currently there are 4,000-5,000 acres of fruits and vegetables grown organically in Ontario. There are opportunities for more growers to participate in the market.

When new growers are considering a move to organic production they often start by asking "What can I use to control 'xxx' pest (be it an insect, disease or weed)?" While this sounds like an easy question, it does not have an easy answer for organic growers.

A basic principle of organic crop production is to be as self-reliant as possible by using on-farm inputs. Where outside inputs are needed, the organic standards require you to use those that are 'found in nature'. Manufactured or synthetic inputs are not allowed to be used. Quite often the management tool is not a product that you need to buy. In all cases organic pest management relies on a combination of many techniques that work together to accomplish the task.

For example, a good crop rotation is the cornerstone of any pest management program on the farm. Continuous or frequent cropping of related crops in the same field will almost always lead to increased pest problems. Tillage and time of planting can also be used to influence the populations of some pests. Resistant and tolerant varieties are also key tools to managing pest populations.

The challenge on organic farms is to set up your cropping system - rotation, tillage, planting, fertility, varieties, etc. - so that you avoid problems. On most commercial farms part of the strategy is to wait and see which pests are present and then spray with whatever is the best product to get maximum effectiveness. The organic grower does not have many pesticide tools available to use after the problem occurs; they need to plan to avoid the problem.

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Avoiding the problem is the 'ideal' system. When everything is working right you can avoid or tolerate many pest problems. There are some pest problems that are very difficult to manage organically. There are some pesticide management tools that organic farmers can use. Bacillus thuringiensis (Bt) is probably the most common used 'organic' insecticide. Spinosad and kaolin give some excellent promise for future products but growers should always be careful to use the correct formulation. Not all formulations of these pesticide products are permitted in organic production; for example at present the only permitted Bt products are some of the dry formulations. Spinosad is allowable but current formulations (Success is registered in Canada) contain inert materials that are disallowed for organic production. Organic growers should always check with their certification agency prior to use to make sure that the intended use and the product is permitted. All organic pesticides have to receive registration from the PMRA. Sometimes the US organic growers have access to products that we do not in Canada.

Diatomaceous earth, repellents, pheromones, traps, trap crops, and predators are all practices that are used in specific situations. Pyrethrum is an organically permitted substance, but frequently it is formulated with piperonyl butoxide, which is prohibited. Rotenone is permitted by organic standards, but is not widely used by our growers and under the standards is not allowed to be used as the primary method of pest control.

For disease control, copper and sulphur have traditionally been used. There is some controversy over copper and likely to be more controls on this product in the future (as now occurs in Europe). Compost tea has gained in popularity in the past couple years and has shown some benefits in suppressing specific diseases. There is, however, still a lot to learn about the how to make and use compost tea on the farm. At a recent conference, two presentations referred to disease suppression by soil mycorrhiza. These beneficial soil fungi are native to our soils and part of the complex of organisms that can be managed to stimulate soils to be more disease suppressive. This is a relatively new field that we need much more information on.

For a more complete list of inputs for crop management on organic farms go to the Directory of Allowable Organic Inputs website put together by the organic associations in Atlantic Canada and is the best Canadian website listing these permitted substances with some explanation on each.

Related Links

• ACORN Directory of Allowable Organic Inputs
  

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