Since Rachel Carson's, Silent Spring, there has been a significant outcry among environmentalist regarding pesticide use. Pesticides scare many people. 10% of the pesticides on the market today are suspected or known carcinogens, and studies are currently being conducted into whether pesticides are responsible for a declining sperm count in males.
The term pesticides covers herbicides, fungicides, and insecticides. Herbicides and insectisides are the most commonly used of the two on annual crops.
Herbicides are used to control competitive weeds. Cultivators and other tillage practices fight weeds mechanically, but they promote soil erosion. If soil conservation is desired, the only other real alternative is the use of herbicides.
Fungicides are used to kill fungal diseases. Fungicides are generally expensive to apply. They are more commonly used on perenial plant & fruit crops.
The use of chemicals for insect control dates back to 1000BC when Homer referred to using sulfer to divert pests. One of the first synethic insecticides was Lethane marketed in 1932. Insectides are easy to apply to fields and cost effective. Their use creates a more affordable and more visually appealing crop. Consumers desire healthy foods, but they buy with their eyes. Often the best looking crop is the one best protected with insectides.
An alternative method of pest control is introducing predatory insects. The predatory insects eat the pest insects. This method can be effective, but it is very time sensitive. If the predatory insects are not released during the currect stage of pest developement, then they fail to protect the crop.
Crop rotation can also reduce the need for pesticide application.
Horticultural oils can kill insects by smothering their pores. They are considered safe for humans and leave very minimal residue. I do not know if they are cost effective for large scale farming practices.
The EPA, which is supposed to regulate and approve new pesticides is actually helping to slow down the introduction of newer safer pesticides. Older pesticides have been okayed for use, but newer, safer, and more effective pesticides are denied permits because they cannot meet the EPA's strict guidelines. I guess the EPA considers it no big deal that we are still using older more dangerous pesticides while better ones sit unused.
The reason people advocating sustainable agriculture usually frown on liberal pesticide use is that the pests can grow resistant. Currently, more than 200 species of insects are known to be resistant to one or more insecticide.
There will always be a need for insecticides, especially as more people demand foods from less cropland. However, perhaps alternative pest control methods should be utilized besides just chemical applications.
Vertebrates are also pests. Rabbits, moles, raccoons, rats, and many other mammels feed of agricultural products. Hunting , trapping, and poisoning is required to reduce their impact. Birds are also a major problem. They feed on seeds and defecate in the seed storage areas. These seeds are then feed to animals or people who can become ill from it.
One of the major criteria of sustainable agriculture is that it must feed the world's population. Modern pest control methods are meant to increase the yield as much is possible.