Aromatic repellent

Fennel now plays a new role as a pest controller

Published: Monday 15 January 1996

FROM rendering aroma to curries and pickles to warding off mustard pests - the common spice fennel or Foeniculum vulgare (popular name saunf) has come a long way indeed. At the Lucknow- based Central Institute of Medicinal and Aromatic Plants (CIMAP), experiments demontrated that saunf grown in between rows of mustard crops effectively controls a major pest of the crop, the mustard aphid (Science Service, Vol 14, No 19).

Several essential oil-bearing plants like Arternisia, coriander and Anethum were tested for their effect on the mustard pest. Scientists found that the lowest incidence of the pest was in fields where mustard was intercropped with fennel.

The finding is significant since mustard is a major source of edible oil in India. Every year its crop suffers due to infestation with aphids, Lipaphis erysimi. These regular outbreaks affect the crop, especially vulnerable from flowering to seed maturity, at all stages. This in turn leads to a considerable loss in yield.

And how does the pest attack its target? It chooses soft parts of the plant like tender stems, flowering parts and unripened seed pods to do the damage. Gradually, it soaks dry the plant of its vital life-giving nutrients, which retards the rate of growth. Thus, Outputs get reduced. As a result, a large quantity of mustard oil needs to be imported every year to meet the domestic demand.

Scientists at the CIMAP report that the effect of fennel is due to some chemicals released by these plants that affect egg-laying in the aphids. This decimates the pest population. Besides benefitting mustard crops, elimination of aphids, which are carriers of viral diseases too, would also mean containing these diseases to some extent.

Supposedly one of the first experiments of its kind, the,work by the scientists at CIMAP upholds the organic method of cultivation. "This approach to cultivation may help improve yield and minimise environmental pollution due to synthetic pesticides", says D Singh, a scientist at CIMAP.

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