Insecticides, Fungicides and Herbicides

Field pests are controlled by applying chemicals to foliage or the soil; crop seed can be dressed with pesticides before sowing, protecting it from subsequent fungal and insect attack. Foliar applied chemicals and seed dressings can have local protectant action or be translocated throughout the growing plant, affording protection to new and developing tissue. Pesticide approval in the UK ensures that treated crops are safe by requiring a suitable interval to elapse between the final spray application and harvesting. However, a small residue is inevitable especially if insecticides and fungicides are subsequently used during storage of the harvested crop. Droplet and particle size of the applied pesticide is important in determining biological efficacy, coverage, tenacity, uniformity of distribution, minimisation of drift and economy in use of the chemical. In 1991, global agrochemical sales amounted to $26.8 billion, with herbicides accounting for 44%, insecticides, acaricides and nematicides 29% and fungicides 21%.