Trinidad and Tobago has acquired a distinct taste for "blue metal" dasheen – a dasheen type that boils to a dark blue colour, is extremely tasty and is the ideal root crop to go with curried duck or iguana. Dasheen corms are an important source of Vitamin C, thiamine, riboflavin, potassium and niacin. Corms can be processed into (dasheen) taro flakes, taro chunks or chips. This bulletin is intended to provide agronomic information for the successful cultivation of dasheen.
There are two varieties of dasheen (Colocasia esculenta) grown locally in Trinidad: "Blue Metal": the corm boils to a light to dark blue colour after cooking and "White Dasheen" which cooks white. In the Caribbean there are other types such as: Common/purple, white; soufe, noir, madere, bunlong.
1. Soil type:
Dasheen can be cultivated in most soil types, the best soils being sandy clay loams that are well drained. This is the only Root Crop that can be grown in flooded conditions although dasheen can also be grown in upland conditions.
2. pH: 5.5-6.5 – difficult to achieve in flooded conditions.
3. Temperature: 25-27o C (hot, humid conditions)
1. Clear land of all grass, brush and trees.
2. Spray a contact or pre-emergent herbicide if necessary.
3. For flooded conditions, clear land, plough and harrow.
4. For flat land, build embankments to retain water.
5. Home gardening: can use run-off water to flood channels (45 cm x 45 cm) planted with dasheen (for leaf production).
Select from vigorous, healthy growing plants, remove all dead material, roots and soil. The upper 2-4 cm of the corm should be intact having a base diameter of 5cm to 7 cm and weighing 150gm to 250 gm.
2. Small corms or 'bullheads':
After selecting the larger corms for sale, the smaller corms can be used as planting material.
Treatment: Suckers and small corms are immersed in a solution containing 90 ml household bleach in 45 liters of water for 15 to 20 min. Dust cut surface with fungicide/insecticide mixture.
Spacing and depth:
55 cm x 55cm (15,000 plants/ha) with a planting depth of 15 cm in lowland conditions.
90 cm x 90 cm (10,000 plants/ha) with a planting depth of 15 cm in high rainfall conditions.
Under flooded conditions, corms or suckers are planted by hand in puddled soil covered with 2-3 cm of water and subsequently flooded.
Planting depth, spacing, soil type and rainfall pattern can all affect the size and shape of the corm.
Keep the base of the plant submerged in 2-10 cm of water as the plant grows. Because the leaves are large, transpiration rates are high. Flooding also encourages sucker production.
Use contact and/or pre-emergent herbicides to control weeds for the first three months of growth (vegetative stage) in upland dasheen cultivation. Hand-weeding using hoes are normally recommended after 3 months.
Prometryne @ 1-2 kg/ha before emergence gives 4-8 weeks of control.
Dalapon or Chloramben @ 2.5 – 3 kg/ha. applied after planting but before emergence.
PEST AND DISEASE MANAGEMENT
1. Taro beetle: (Ligyrus); controlled using Malathion ®
2. Aphids in the dry months. Can be controlled with Cypermecthrin ® and/or
3. Caterpillars feeding on the lamina can be controlled by hand-picking or using biological chemicals
4. Taro Leaf Blight (Phytophthora spp.) A fungus which can be controlled with a copper fungicide.
5. Brown leaf spot – Cladosporium colocasiae. A copper fungicide can be used to manage leaf spot.
6. Shot hole leaf spot – Phyllostica spp. Proper field husbandry can help to control this problem.
7. Corm rot: Phytophtora and Pythium spp.: Death of young plants, wilting, stunting, chlorosis and subsequent collapse of the whole plant. Dip plants in, as well as drench the land with copper fungicides.
8. Soft rot: Fusarium oxysporium causing a whitish-grey spongy soft rot with a brown margin. Foliage wilts and plants collapse. Can be controlled using a soil fungicide and good field management.
9. Dasheen Mosaic Virus- rogue plants, remove away from fields and destroy plants.
10. Root Knot nematode – Meloidogyne spp. can be controlled with a nematicide or dip planting material in 100°C water for 50mins.
A soil test should be done to determine fertilizer types and rates and also any limestone requirements. The following fertilizer recommendations can be useful:
1. NPK MgO (15:8:12 +2) applied at 2 and 8 weeks after planting at 57 g/pl. in a circle 18 cm from the base of the plant.
2. 112 kg/ha N, 13-26 kg/ha P and 48-96 kg/ha K applied in a split dose at
planting and 3-4 months later.
Nitrogen deficiency: uniform yellowing of the lamina and development of a purple colour along the petiole.
Potassium deficiency: Marginal chlorosis of the leaves, roots die.
Zinc deficiency: Inter-veinal chlorosis, narrow leaves and cupping of the leaves.
Mould 1-2 weeks after the first application of fertilizer 15-30 cm around the base of the plant in upland dasheen production.
The maturity period is 6-7 months after planting in drier areas and 9-10 months in wetter areas. Tubers can be harvested using a fork. Leaves turn yellow, dry and shrivel at maturity.
Prepare the corms by removing the soil and fibrous roots. Sort by size and clean in running water within 4 hours after harvest. Treat with Ridomil MZ (14 gms/23 liters of water) for 2-3 minutes to prevent fungal attack or use a solution of household bleach (19 ml bleach in 10 liters water).