Diseases are a major source of crop and plant damage that can be caused by a number of plant disease-causing organisms. Fungi are the number one cause of crop loss worldwide. Viruses, nematodes, and bacteria also cause diseases in plants . Symptoms resembling those caused by pathogens can be caused by non-living factors, such as nutrient deficiency and air pollution and also insects

Fungicides, herbicides and insecticides are all pesticides used in plant protection. A fungicide is a specific type of pesticide that controls fungal disease by specifically inhibiting or killing the fungus causing the disease.

When properly applied at the correct times, fungicides usually perform very well and have an acceptable margin of safety to humans, wild life, and crop plants. However, we still need fungicides, diseaase controlnew fungicides for several reasons. Despite the large total number of fungicides that are available, each particular crop disease typically is well controlled by only two or three marketed fungicides, each with its strengths and limitations. A wider choice of treatment is desirable for many crop diseases. The development of resistant mutants of target pathogens has led to losses of effectiveness, in certain regions and uses, of most of the modern fungicide classes. Further resistance problems seem likely to arise despite the considerable efforts of the agrochemical industry and farm advisory services to promote the use of countermeasures. New types of fungicide can act as effective replacements for these problem situations and also increase the diversity of treatment, which is a mainstay of fungicide resistance management. Certain fungicides, for example, captafol, binapacryl, organomercurials, and ethylenebisdithiocarbamates, have been banned from or restricted in commercial application because of perceived toxicological risks or because manufacturers are not prepared to do additional toxicological or environmental safety evaluations required by regulatory authorities, and further withdrawals for these reasons are likely to occur.

Benefits of using Fungicides:

  • To control a disease during the establishment and development of a crop.
  • To increase productivity of a crop and to reduce blemishes. Diseased food crops may produce less because their leaves, which are needed for photosynthesis, are affected by the disease . Blemishes can affect the edible part of the crop or, in the case of ornamentals, their attractiveness , which both can affect the market value of the crop.
  • To improve the storage life and quality of harvested plants and produce. Some of the greatest disease losses occur post-harvest . Fungi often spoil stored fruits, vegetables, tubers, and seeds. A few which infect grains produce toxins capable of causing severe illness or even death in humans and animals when consumed. Fungicides have been used to reduce mycotoxin contamination in wheat affected by Fusarium head blight, but most fungicides developed so far have not been sufficiently effective to be useful for managing mycotoxins associated with other diseases.

Fungicides are applied as dust, granules, gas, and, most commonly, liquid. They are applied to:

  • Seed, bulbs, roots of transplants, and other propagative organs. These treatments are usually done by the seed company. Some treatments need to be done by the grower on-site at the time of planting. The goal is to kill pathogens that are on the planting material or to protect the young plant from pathogens in the soil.
  • Soil either in-furrow at planting, after planting as a soil drench , or as a directed spray around the base of the plant.
  • Foliage and other aboveground parts of plants by means of a sprayer.
  • Inside of trees via trunk injection.
  • Air in enclosed areas such as greenhouses and covered soil. Fungicides are called fumigants when applied as a vapor-active chemical in the gaseous phase. Some fumigants are also active against nematodes, insects, and weed seeds.
  • Harvested produce, as a dip or spray in the packinghouse.