Researchers from INRA (France’s National Institute for Agricultural Research) have reported on their long-term experimental work on apple orchards, which has seen them reduce pesticide use by up to 50% through a series of measures based on increased forecasting and observation of pests and diseases.
INRA and its partners have been experimenting with three orchard systems using three different apple varieties since 2004. It’s work with potentially major consequences as apples are a crop worth €4 billion in the European Union and conventionally subject to a range of insecticide, fungicide and herbicide treatments.
INRA’s broadly similar organic and ‘eco’ systems have seen them reduce the average number of annual treatments from 35 to 20 with the major difference between the systems being the fact that synthetic inputs can be used as a last resort in the latter. Crucially, these reductions have only been possible using varieties offering good resistance to pests and diseases (Ariane, pictured above right, and Melrose), while the most commonly grown apples in France are in the Golden Delicious family.
Agronomist Sylvaine Simon explained to the INRA website that the ‘eco’ system was the more innovative, demanding access to information, regular observation in the orchards and excellent reactivity with the window of opportunity for treatments as little as an hour or two. She added that yields in the organic system, better known and based on prevention, may be reduced and the fruits smaller, but the organic label adds value to the crop.
Questioned about the feasibility of these systems for producers, she said that biocontrol, one of the major levers, is already widely used by French producers with, for example, between 80 and 90% of orchards using sexual confusion in the south of the country.
Other measures require a rethink before orchards are planted or replanted. For example, mechanical weeding can replace herbicide use but is not possible if ground-based irrigation systems have been installed. Similarly, there is the question of variety, which is tricky given that orchards are generally in place for around 20 years and the downstream chain (cooperatives, processors and even consumers) plays a pivotal role in varietal choice. Less than 10% of France’s apple growing area is planted with varieties resistance to scab, the crop’s main disease, she added.
Researchers will now be taking a two-track approach to going beyond a 45% reduction in pesticide use with no yield penalty. In the organic and ‘eco’ systems they will be taking a step-by-step approach, reducing the use of copper and sulphur as fungicides, for example, and replacing the use of neonicotinoids to control aphids with the use of repellent plants, such as marigold and rosemary.
At the same time, they are developing a new trial where rather than a step-by-step approach, they will be designing a ‘zero pesticides’ system from the outset. This, she explained, will involve a diversified agroecosystem composed of a mosaic of fruit trees and service plants with different roles: acting as a barrier or diluting pest pressure, plants which repel pests and those which attract beneficials etc. This will require thinking beyond the plot and rethinking the marketing methods for a diversified production.
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