Among the limiting factors of agriculture are insects, diseases, weeds, rodents, and birds, which affect both plant and animal production. It is not only that insects, diseases or weeds act as a limiting factor of agricultural output, but also that their unexpected massive development in the form of a pest can, in a few hours, destroy crops or entire crops.
Pests are a permanent latent risk and have been a recurring event in the history of agriculture.
The magnitude of the pests varies between regions, particularly between temperate and tropical or subtropical. It has been pointed out that a crop in developing countries competes with at least 10 to 50 different varieties of weeds.
To combat pests, traditional agriculture has applied various practices: crop rotation, crop combinations, development of more resistant varieties, and use of natural pesticides, such as the use of neem which are seeds to protect both crops and stored grains.
In modern agriculture, pesticides of different types play an essential role: fungicides, insecticides, and herbicides, among others.
Pesticides and Pests Development
The basic principle of these chemical compounds lies in their toxicity with respect to at least one of the objectives (the type of insect, weed, etc.); but since the degree of specification of such compounds is not precise, they are also toxic to other species or alter their behaviour. These unwanted objectives are often central to the agricultural process, or to the biological functions of the land.
The problem of the development of resistance in the insects and plants attacked by the pesticide has acquired alarming characters. Today it is common to see that one weed succeeds another, or that one insect replaces another or, finally, that a species develop resistance to certain compounds.
The massive discharge, the persistence and the concentration of toxic compounds in the natural environment create mechanisms of adaptation in insects, weeds or bacteria.
Today more than 520 insects, 150 species of plant diseases and about 110 weeds are resistant to pesticides, fungicides or herbicides. Before 1970, resistance to weeds, resistance to insects and plant diseases had not been detected, although they were detected several decades ago.
Currently, more than 700 pesticides are commercialised. One of the characteristics of the pesticide market is its high concentration in a few products: more than 50% of the pesticides are applied to wheat, corn, cotton, rice, and soybeans.
The principles of ecological selectivity and biological control, the selection of resistant genetic varieties and the study of the dynamics of pests should be part of agricultural practice. This integrated control also translates into a significant reduction in the consumption of pesticides.
Integrated pest management considers plants and pests as integral parts of the ecosystem and seeks the use and combination of natural factors that limit the emergence of pests together with agricultural practices, resorting as little as possible, and selectively or in extreme cases, to use of agrochemicals.
An integrated pest control system includes: crop rotation, inter-cropping, biological controls, the use of bio-pesticides, the study of populations and precautionary systems integrated into health programs.
The greatest difficulty that the development of integrated pest control in Dubbo has found is that being an intensive system in the use of knowledge, it requires special rural training programs that reach large sectors of the rural population.