Use of derris as botanical pesticide

Derris

Derris elliptica, commonly known as Tubli, Tibanglan, Tiba-lau, Malasiag, Bauit or Tugleng Pula, is a bushy leguminous vine usually found growing near river banks or streams. The dark-green compound leaves usually have 9-13 sword-shaped to oblong leaflets with pronounced pointed tips.

The roots of Tubli contain rotenoids, a highly potent insecticidal chemical which is widely used for the control of a variety of insect pests in the home, on domestic animals and on the field. It is also widely used as fish killer. On field crops, it has a short (3-5 days) residual toxicity and the residues are non-toxic to man.

SELECTION OF PLANTING MATERIAL

Twist the roots of Tubli plants and observe the amount of milky sap that oozes out. Get stem cuttings only from whose roots contain a lot of sap since potency has been associated with sap content.

PROPAGATION

Tubli is easily propagated using 10-30 cm mature brown stem cuttings with 1-3 nodes and at least 5 mm in diameter. Plant the cuttings in sand or well drained top soil, either in plastic bags or in mist beds.

When rooted directly in plastic bags, place them in shaded locations and spray with water at least 3 times a day. Fitly to sixty percent of the cuttings will root successfully. The plants will be ready for transplanting in 34 months.

Rooting can be increased to almost 100 percent if the cuttings are allowed to root for at least 45 days in mist beds prior to bagging.

PLANTING

Tubli grows best when grown in unshaded areas. It is planted from 0.3-1.0 m apart, either in between perennial crop rows as a cover crop or as part of a contoured vegetative terrace. Plant at the start of the rainy season.

CARE AFTER TRANSPLANTING

Tubli is a relatively slow grower and will need frequent during the first year. Irrigation improves plant growth. Though it is N-fixer, it will benefit from the application of 50 and 100 9 14-14-14 during the first and second years, respectively.

HARVESTING

Tubli roots can be harvested 4 months from transplanting although the highest root yield per plant is attained at 1.5-2 years from planting. Early harvesting is suggested in areas with deep soils to forestall the development of deep roots which are difficult to harvest.

PROCESSING

Tubli roots can be dried, powdered, then mixed with clay (kaolinite) at a ratio of 1:4. The mixture can be dusted directly on plants stored in sealed, black plastic bags for future use.

For spraying, freshly harvested roots are crushed finely and suspended in water at the rate of 40 9 fresh roots per 20 l water. Spray Derris extract only after 5 p.m. to maximize toxic effects. The solution can be used as shampoo for animals to eliminate fleas and ticks.

For the elimination of trash fish, a jute bag containing about 1 kg of crushed root is immersed in the pond.

Note: The above rates are tentative and should be adjusted depending on the original toxicity of the roots and the type of pest.