Enjeux - Should plant protection products be banned ? Enjeux - Should plant protection products be banned ?

Should plant protection products be banned ?

Used intensively for nearly 50 years to defend crops from weeds, insects and diseases, plant protection products are the target of harsh criticism today. They are attacked for their effects on the environment and public health, for their impact on ecological balances and for being used excessively. Do they really work? Are they harmful to humans, to the soil, to water and air quality? Could we get along without them? Could they be better managed? In this report we look at these products from a number of perspectives to try to gain a clearer understanding of these issues.

CONCEPT

Définition

Plant protection products, also called “phytopharmaceutical products”, “phytosanitary products”, or simply “pesticides”, are used to keep plants – in most cases, agricultural crops – safe from insects, diseases and weeds. They are composed of one or more active substances, which are diluted (or “formulated”, to use the technical term) with binders and possibly additives, and then with water or solvents if the final product is a liquid. A plant protection product is not necessarily made from synthetic molecules; it can also consist of natural organic molecules.
Like medications, plant protection products must be analysed in a series of regulatory studies to confirm they are risk-free under normal conditions of use before they can be put on the market. They cannot be sold without authorisation.

Plant protection products no to be confused with fertilisers

Plant protection products and fertilisers are both widely used in agriculture, but the former are intended to protect crops against pests, while the latter provide plants with the nutritive elements that they need to grow (e.g. nitrogen, phosphorus, potassium and magnesium). Both plant protection products and fertilisers may be either chemical or natural in origin.

What plant protection products do

These products fall in several categories:

  • Insecticides eliminate insects or disrupt their life cycle to keep them from multiplying and destroying crops. In France, the most harmful insects are aphids, which can transmit diseases, and Colorado beetles, leafhoppers, and click beetles. In some countries, insecticides are used to kill locusts, which can be very destructive.
  • Herbicides, or weed-killers, control the growth of self-propagating plants that compete with crops. Coach grass, thistle, goosefoot, shiny black, mustard weed…the list of such plants is long. Herbicides are also used to eliminate weeds on pavements, railway tracks, paths, green spaces and similar areas.
  • Fungicides protect plants from diseases caused by fungi. The most common of these diseases are mildew and oidium as well as rust fungi, which attack many kinds of plants. Certain very destructive diseases like septoriose, botrytis, sclerotinia and some others attack a smaller variety of crops.
  • Molluscicides are used to fight against slugs and other molluscs.
  • Growth regulators are employed for varying purposes depending on the crop. In the case of cereals, they limit the plant’s height and thicken its stalk to boost grain yields and lower the risk of the stalk’s breaking in storms or very strong winds. Fruit-growers use them to reduce the quantities produced in order to obtain larger fruits of more even quality.

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Imprimer

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A little history

Plant protection products have been in use for many years.

- Products made from arsenic (notably copper arsenate) have been employed since 1865 as an insecticide to keep the Colorado beetle from ravaging potato crops. Though banned today, sodium arsenate was long used in France to protect grapevines.

- The famous bouillie bordelaise (Bordeaux mixture) made from copper sulphate and lime, was invented by a chemist from Bordeaux named Ulysse Gayon and the botanist Alexis Millardet in the early 1880s to protect grapevines from mildew. It is still used today for this purpose as well as for many other crops, especially in organic farming.

- DDT was developed in 1874, but it was not until 1939 that Paul Hermann Müller recognised its insecticide properties, a discovery that earned him the Nobel Prize for medicine in 1948. DDT came into wide-scale use after the second world war to battle insects and in particular the mosquitos that carry malaria and typhus. The work of an American biologist revealed DDT’s cancer-causing effects, leading to its being banned in many countries in the early 1970s. However, its use is still allowed in some tropical countries.