Information on the Safe Use of Pesticides

Introduction

Herbicides and How They Work   

Insecticides and How They Work

Fungicides and How They Work

Pesticides for Pest Control

Adjuvants, Dyes etc

How long does it take for a new Pesticide Active Ingredient to be available?

Examples of pesticides etc used in Amenity Horticulture can be found here

Introduction

In 2500 BC the Sumerians were using sulphur compounds to control insects and mites and this was the first documented use of pesticides, for further information follow this link.

Nowadays we use the term Pesticide as defined in the Control of Pesticides Regulations 1986 (as amended by the Control of Pesticide (Amendment) Regulations 1997), regulation 3.  Briefly, it means any substance, preparation or organism that is prepared for or used to control any pest. A pest is any unwanted plant, harmful creature, or organism that is harmful to plants, wood or other plant products.

You may also come across the term Plant Protection Product, this is defined in the Plant Protection Products Regulations 2005, regulation 2.  Throughout the code of practice for using plant protection products the term ‘pesticide’ is used to cover pesticides and plant protection products.  ‘Pesticides’ and ‘plant protection products’ are herbicides (products to kill weeds and other unwanted plants), insecticides (products to kill bugs), molluscicide (products to kill slugs and snails) vertebrate control agents (products that control small animals and birds, such as rodenticides, which kill rats and mice) and so on. 

Herbicides and How They Work   

What is a herbicide? - A chemical that kills or inhibits the growth of weeds.

Insecticides and How They Work

What is an insecticide? - Preparations intended for preventing, destroying, repelling or mitigating any member of the class Insecta or allied classes in the phylum Arthropoda.

• Non-selective - kills a very wide range of insects

• Systemic - the pesticide is absorbed by the pest and moves around within the pest system to reach parts of the pest remote from the point of application

• Contact - directly affect the parts of the insect to which they are applied. They cause localised damage to the animal tissue on contact.

• Repellent - Repels insects, mites, ticks or pest vertebrates (dogs, rabbits, deer, birds)

• Attractants/Pheromones - Attract animals, especially insects usually into traps. Often sexual pheromones.

• Chemosterilants - Sterilise insects or vertebrates (birds, rodents). Will usually sterilise males.

• Feeding stimulants - Causes insects to feed more vigorously

Fungicides and How They Work

What is a fungicide? -  A chemical or physical agent that kills or inhibits the development of fungus spores or mycelium (or when used in a broad sense bacteria). The term 'fungicide' includes all preparations intended for preventing, destroying, repelling or mitigating any fungi. Fungi includes all such organisms as rusts, smuts, mildews, moulds, yeasts, viruses and bacteria, except those on or in living man and other animals.

Types of disease: - There are two types of disease, non-infectious and infectious. Non-infectious diseases result from:

1. temperature, water or light stress;

2. essential nutrient deficiencies;

3. inorganic and organic toxicities;

4. soil oxygen deficiencies;

5. atmospheric pollution;

6. soil acidity or alkalinity;

7. mechanical injury; or

8. genetic defects.

Fungi, viruses, bacteria, mycoplasma, nematodes or parasitic higher plants cause infectious diseases. All of these are biotic, but they have different effects and affect the plants in different ways. The fungi act as parasites meaning that they live off another species and therefore they kill it.

• Curative - This means that they are active against pathogens that have already infected the plant, thus there tends to be a higher risk of pathogens developing resistance to the fungicide. A resistant pathogen is less sensitive to the action of the fungicide, which results in the fungicide being less effective or even ineffective. Since these curative fungicides must be able to penetrate into plants and selectively kill the invading fungi, they are designed to target specific enzymes or proteins made by fungi. Since the mode of action of these fungicides is so specific, small genetic changes in fungi can overcome the effectiveness of these fungicides and pathogen populations can become resistant to future applications. For information on resistance in turf diseases see this publication

• Systemic - These fungicides (also called penetrants) are absorbed into plants. Some systemics move very short distances from the site of application, such as across a leaf blade from one surface to the other (local systemic or translaminar). Some fungicides are weakly systemic and can move further from the application site than local systemics. Most systemics move more extensively because they are mobile in xylem tissue. When applied to the root zone, these are absorbed by roots and then move upward through the plant with the transpiration stream (xylem-mobile systemic). Xylem-mobile systemics applied to leaves move throughout the leaf where deposited, but cannot be redistributed out of that leaf; however, any material deposited on stems can move upwards into leaves. Phloem-mobile systemics (also known as "true" or amphimobile systemics) have bi-directional mobility, some material moves in phloem out of the leaf where deposited upwards to other leaves and downwards to roots. Systemics cannot move again after translocation.

• Contact - These fungicides (also called protectants) remain on the surface of plants. Many contacts are potentially phytotoxic (toxic to plants) and can damage the plant if absorbed.

Pesticides for Pest Control

Worm control agent for the suppression of worm casts

These are usually fungicides with a dual action to suppress worm activity in the top few cms of the turf. Miildothane Turf Liquid, the main product available will no longer be able to be used after 30th August 2008 and supplies are very difficult to get hold of at the time of writing (November 2007).

Adjuvants, Dyes etc

What is an Adjuvant? - A substance other than water without significant pesticidal properties, which enhances or is intended to enhance the effectiveness of a pesticide, when it is added to that pesticide.

All adjuvants sold in the UK have to be authorised by PSD. They scrutinise data such as effect on pesticide residues, mammalian and aquatic toxicology, environmental data etc. Provided the information is acceptable, the adjuvant is authorised and given a unique adjuvant (ADJ) number.

Some Amenity products already have an Adjuvant pre-mixed, for example the herbicide Roundup Pro Biactive.

Other additives not legally classed as Pesticides or Adjuvants - These include spray tank cleaners, dyes, anti-foaming agents and foam bout markers.

How long does it take for a new Pesticide Active Ingredient to be available?

• Research chemists and biologists suggest a novel compound; the patent officer checks that neither it nor the functional groups suggested have already been patented.

• Research chemists synthesise the compound on a small scale (100 g).

• Biologists test its action in a greenhouse; toxicologists test it for toxicity.

• Economists assess the feasibility of launching such a compound; marketing specialists decide whether there is a market for the product.

• The patent officer applies for a patent.

• A pilot plant is set up to synthesise the product on a larger scale (100 kg).

• REM (Residue environmental metabolism) specialists use a ‘typical’ production sample to determine the degradation, soil mobility, and metabolism of the product in the environment;

• Toxicologists carry out further toxicology studies using typical production samples;

• Agronomists test typical production samples in the field. (These tests take 2–3 years because one farming cycle takes 12 months.)

• Process chemists determine the most economical and efficient method of synthesising the product on a large scale, using readily available starting materials. This takes up to 12 months in the first instance, but is a continuous process once the decision to produce the compound has been taken.

• The formulations chemist researches the most effective way of applying the product in the required dose, and conducts storage stability tests at different temperatures.

• Formulations chemist also researches the best way of packaging the product. (The formulations chemist takes 2–3 years to complete work on a product.)

• The registration specialist will compile documentation for the registration authorities, using the data and reports from the REM, toxicology, and agronomy experts (approximately 3–4 months); then applies for registration.

• Registration typically takes 4 years to come through in the UK; 12–18 months in France; and 18–24 months in Germany and Holland.

• Economists will make out a case for the construction of a site to manufacture the product should registration be granted. Alternatively, they might suggest contracting a different site to manufacture in the first instance so that the market can be tested.

• Marketing specialists, some of whom will be regional – ie based in different parts of the world – will decide how to launch the product, and when to launch it for maximum capture of the market.

• The patent officer might now apply for further patents to protect the product, or compounds with a similar structure, from being produced by competitors so that they get a share of the market.

• Economists agree to start constructing of a full-scale plant, or contracts signed with other sites for manufacture of the product, subject to registration being granted

• Registration comes through; product is launched.

Last modified: Tuesday January 22, 2008                                                                                                 Copyright © Ian Gower Associates Ltd 2008