SWEET FLAT – Acorus calamus

General

Sweet flag isa perennial plant native to India which has achieved worldwide distribution because of its high medical value. Swamps and still waters are its typical habitats where it can developp considerable stands. It ill grow in situations up to 2000 metres. At these elevations it develops its greatest essential oil content (71).

Sweet flag is easy to cultivate. Due to its site requirements it does not compete  ith other crops. In India over 4000 kg of dried rhizomes per hectare can be harvested annually (149). Even through its cultivation is easy and the possibilities as insecticidal plant in field and store are promising its practical importance is still minimal. Scientific investigation started about 1939.

Effective Range

Inseticidal, repellent, antifeedant, antifertile (94).

Espace pour photo de sweet flag

Target Insects

Adzuki bean beetle               - Callosobruchus chinensis  (52)

Army worms                          - Spodoptera litura                (52)

Fleas                                      - general                                (52)

Khapra beetle                       - Trogoderma granarium                (52)

Large cabbage worm           - Pieris brassicae                           (13)

Lesser grain borer                - Rhizopertha dominica                  (52)

Mediterannean fruitfly           - Ceratitis capitata                 (52)

Melonfly                        - Dacus curcubitae                (52)

Oriental fruitfly                       - Dacus dorsalis                    (52)

Rice weevil                            - Sitophilus oryzae                (52)

Remarks

*It has been established that sweet flag is not poisonous to hu-mans and warm blooded animals (100). No harmful resuls have been experienced w    handling the essential oil except for a slight uneasiness and itching of the eyes when the treated seeds were looked at constantly for a considerable length of time (160).

*When used against pests in the field the crop itself suffers no damage (149).

*When used on crops in store, the germination power is not harmed and the food quality does not suffer (160).

Methods of Use

Tests with dried rhizomes in powdered form or in water solutions have demonstrated the effectiveness of sweet flag against beetle larvae and aphids. Water solutions benefit from the addition of a little soap which disperses them better over the leaf and makes them more adhesive.

A useful mixture is 30 gm rhizome powder in 4 litres of water which is either allowed to stand cold for a day or boiled for 45 minutes and cooled before  spraying (149).

Sweet flag as an insecticide can be used both in field and store. Most of the available information concers the latter. Practitioners interested in experimenting  could contribute a great deal  enhance its practical use.

Published results about the use of sweet flag to protect crops in store are mostly based on scientific work. When stransferring scientific results to practical work, data on quantities used are to be considered as a guideline. They have to be adapted to local requirements, as the influences in field conditions are more complex than under laboratory conditions.

Rhizomes of sweet flag are used in two ways :

Powder

Essential oil

*Before grain is stored it should be well mixed with dried, powdered sweet flag rhizome at the rate of 50 kg grain : 1 kg sweet flag (149).

Another source recommends a rate of 100 kg rice : 1 kg sweet flag rhizome (71).

*The effect of the essential oils of  sweet flag  rhizome on the Adzuki bean beetle (Callosobruchus chinensis) has been investigated by YADAVA (160) with the following results.

5 different formulations were tested with references to knock-down effect (50 % and 100 %) and mortality (50 % and 100 %). The essential oils were obtained from the rhizomes by steam destillation.

Chickpeas were thoroughly coated with wich of the above formulations. About 250 gm of so treated seeds were then put into jars. Into each were then introduced 50 adult weevils.

All formulations were found to be effective. None of the weevils survived and the seeds was not affected. In creased concentratinos brought about an earlier onset of the knock-down effect and a quicker death, particularly in the caes of kerosene preparations. The protection appears to last longer when the treated seed is not exposed to sunlight.

Conclusion :

The dried seeds should be dressed with 2 % or 4 % its solution in alcohol or 2 % or 4 % emulsion in water before taking them to godown. This treatment will keep the storage free of pest for  at least 4 months. After that, if necessary seeds may be redressed or a light spray with its alcoholic formulation on the heap will suffice to ensure the store to be free of beetles for at least another 6 months.

As its 2 % solution or emulsion may become weak within a short time, the 4 % may preferably be used for a long term  storage. The seed dressed with its water-emulsion should by all means be dried before taking them to store. The mixture of essential oil and water should be vigourously shaken before use (160).