7.3 Natural Management

The basic guiding principle of natural pest management is that there is no such thing as a pest problem. If the ecological balance in the agricultural land is not disturbed then the appearance of the pest is not a problem but a symptom. If the symptoms appear, we should try to find out the causes (disturbing factors) and remove them in order to recover the ecological balance. Only this approach can avoid the same mistake the next time. There are two measures, preventive and control. The most emphasis should be put on preventive measures, however, control measures may be necessary in the initial stages of ecological agricultural practice. If proper preventive measures are taken, control measures will not be necessary.

Preventive measures have indirect effects and are a long term process. That is why farmers are not very interested in using these methods. From the ecological point of view it is the only way to permanent solution of pest problems. Therefore, much emphasis (more than 90%) should be put on preventive measure.

Create a Balanced Agro-Ecosystem

It is diversity which has the most important role in building up ecological balance in agricultural land. The elimination of disturbing factors is also very important. Methods include:

1. diverse cropping (Section 6.3)
2. mixed cropping, including insect repelling herbs and medicinal plants (Section 6.5)
3. planting perennial trees and grasses (Section 5.5)
4. no use of agricultural chemicals (Section 5.1)

Create a Balanced soil Ecosystem

A balanced soil ecosystem (balance in micro-organisms) is the key element in the health of plants. Almost all plant diseases come form this imbalance which is mainly created by a lack of organic matter, continuous cropping and use of agricultural chemicals which kill micro-organisms. Methods maintain this balance include:

1. crop rotation (Section 6.4)
2. regular supply of organic matter (Section 5.1)
3. avoid mixing raw organic matter with soil (Section 5.1)
4. no use of agricultural chemicals (Section 5.1)

Others

1. good seed selection (no disease contamination, etc.)
2. planting at appropriate time
3. appropriate spacing, etc.

Actually, the cause of pest outbreak is not simple but very diverse and complicated. If we face a pest outbreak, we should reconsider the methods we are using for growing our crops and find out what is wrong. The insects and diseases are the indicator, not the problem.

Despite preventive measures, some pest problems may occur in the early stages of ecological agricultural practice because the health of the soil is not fully recovered form the effects of chemical agricultural practice and the ecosystem is not yet balanced. In this case, it may be necessary to undertake control measures to protect the crops.

Physical Control

This method is very simple and easy, and effective in the early stages of insect outbreak.

1. hand picking – remove / catch the insects by hand or net
2. light trap – put a light above the water of a bucket; insects come and fall into the water
3. stick setting – becomes a place for birds that eat the insects
4. scare crow – something which scares birds that eat grain
5. net cover to protect crops (e.g. cabbage) from insect attack

Natural Pesticide

There are many natural things which repel or kill insects. Common natural pesticides in Bangladesh include:

1. ash (powder)
2. neem leaves and seeds
3. tobacco leaves
4. jute seeds (powder)
5. chili
6. bishkathali (hydro piper)
7. other locally adapted plant leaves

A way of using the plant leaves is to soak them in water for a night or so to take out extracts. The extract water is then used as a natural pesticide.

Natural Crop Protection in the Tropics by Gaby Stoll is a very appropriate book for natural pesticides. (Margraf Publishers, Muhlstr. 9, D-6992 Weikersheim, Germany)