Pest and Disease Management
Pest and Disease Management
Non-chemical (or ecologically friendly) methods of crop protection have been practiced over the centuries, but the introduction of chemical pesticides a few decades ago seemed to make crop protection easier.
Products proved to be effective at first as it was thought that all pests could be eradicated. However, the pests were not eradicated, as they came back over and over again, every growing season. Many natural enemies were temporarily wiped out along with the pests, which gave pests the opportunity to multiply even more explosively than before.
It is necessary to spray several times per season in order to control even just one type of pest and to ensure healthy crops. Eventually, some pesticides do not work anymore because pests develop a certain resistance to them. Initially, this happened with pesticides used against insects and mites (insecticides), but eventually some pesticides used to control diseases (fungicides and bactericides) and weeds (herbicides) also have become ineffective. Given that pests were becoming resistant to frequently used chemicals, there is a continuous need for new chemicals, chemical compounds and mixtures.
Moreover, some pesticides are extremely poisonous for the users. Farmers are expected to know how to handle chemicals safely, without incurring accidents.
More than just to affect farmers directly, it has been shown that their is a correlation between the use of pesticides by farmers and birth defects of their children, in particular boys being born with genital defects:
It is not economically easy to compare the cost-effectiveness of chemical and organic crop protection systems. Especially if looking at one crop or one year alone, farmers tend to under-estimate the costs of chemical control and over-estimate the costs (especially the labor costs) of organic control. The costs of chemical control include not only the pesticides, but also equipment, protective clothing, safe storage and depreciation costs. Often, health costs have to be considered in case of accidents.
In addition, in remote areas, the local market price of the crop may not cover the costs of the pesticides.
Chemical pesticides are often effective against the target pests. However, if the pests become resistant to the pesticide, or if crops suffer unfavorable weather conditions, costs incur and there is no crop yield to pay for them.
Organic crop protection is often less effective than chemical crop protection, but it is usually less expensive, and is based on locally available inputs and interventions.
The undesired side effects of chemical pesticides make it difficult to combine them with many non-chemical methods.
This chapter does not give farmers ready-to-use formulas on how to respond to pest X in crop A or to pest Y in crop B. It provides a more flexible way of thinking and working, which farmers can adapt to local conditions and to the crops cultivated.
Whether a farmer applies non-chemical crop protection methods or chemical pesticides, he or she must be able to recognize the most important pests that occur on the farm. It is also important to know more about their life cycles and how they are affected by local conditions.
The chapter summarizes the most important characteristics of pests and explains how farmers can learn to control them in a responsible way. The intention is not to eradicate pests, but to minimize their harmful effects.
Also, the chapter describes how farmers can organize their farming activities in such a way that pests have less chance of multiplying at an explosive rate. Many of these measures are effective for several years and help to control more than one type of pest.
Many measures to protect crops from pests are taken before or during cultivation. These measures are usually directed towards keeping down the numbers of a specific type of pest or category of pest organisms.
One example is the use of healthy seeds to prevent a crop from becoming diseased at an early stage of growth. Another example is sowing a crop in rows so that weeds can be removed using a hand tool. Yet another example is planting a Neem tree, which keeps many pest insects at bay.