Problems in Development, Registration, and use of Fungicides

Abstract

The basic goal in the development, registration, and use of fungicides is to provide the grower with materials that will give satisfactory and economical control of plant disease and that present only acceptable risks in their potential effects on the consumer, the user, and the environment in general. Only generalizations can be made regarding disease losses throughout the world, but the losses in spite of the controls used today are enormous. Recent estimates (2, 3) indicate that the worldwide annual loss to disease in wheat, rice, and corn is equivalent to 86 million metric tons. To put these losses in perspective compare them with the following production figures. In 1974 the United States produced 48 million metric tons of wheat and India's combined production of rice, wheat, and corn totalled 87 million metric tons (5). These estimates do not include storage losses due to fungal attack nor do they include those frequent situations where a crop is not grown at all in a region because of the almost total loss to disease. With the present world food situation it is even more necessary that disease losses be mini­ mized. Certain fungicides are no longer effective because of the development of resistance by the fungi. An example of such developing resistance is to the benzimidazoles. Other compounds have had their registration withdrawn because of hazards asso­ ciated with their use, i.e. organic mercurials useful as eradicant foliage sprays and seed treatments. There is a need to develop other materials to replace these com­ pounds as well as to control those diseases for which there is yet no satisfactory control. The entire complex of soil organisms causing root rot and wilt diseases cannot now be economically controlled by fungicides. The discovery of effective fungicides for controlling these organisms might easily double the world market for fungicides. An adequate number of alternative fungicides should be available so that growers will not be without effective control agents should a particular material suddenly