Post Harvest Management: Dasheen

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Production Characteristics

Dasheen is often produced on land ill-suited to intensive cultivation techniques, such as steeply sloping or swampy areas. Its high moisture requirements necessitate high rainfall year round for production (such as in Portland) or seasonal heavy rains for one crop per year (e.g. Clarendon) or waterlogged swamp conditions (e.g. parts of Westmoreland).

Wetland Dasheen this is produced in highland areas of year round high rainfall, such as in Portland which receives more than 3,800 mm (150”) of rain per year. Wetland dasheen in

Jamaica produces many basal suckers or cormels, which are used as planting material. These cormels range from 4-11 per corm.

During harvest these suckers break off, or are removed leaving basal wounds which heal less easily than wounds occurring at the top of the corm. These then act as entry points for soil pathogens, resulting in post harvest microbial rotting. The shelf life of wetland dasheen is reduced by this.

Dryland Dasheen

This type of dasheen is produced in highland areas, in generally lighter soils, such as Clarendon and parts of Manchester, which receive 1200-2500 mm (50-100 inches) of rainfall per year. Although farmers tend to stagger planting, there is less dryland dasheen available between June and October.

Crop rotation is commonly practiced in dry- land area. Dryland dasheen generally produce fewer suckers (0-4) so the tops are cut and retained for use as planting material. These wounds heal easily. The good wound healing response at the cut top of the corm, together with few sucker-removal scars at the base of the corm, gives dryland dasheen a longer shelf life than its wetland counterpart.

This type is well-suited for the export market.

Swampland Dasheen

This is produced in low-lying swampy areas, or by river banks (e.g. areas of Westmoreland), on land that is ill-suited to any alternative cultivation.

It is effectively grown pure stand but plant care is minimal after planting.

The tops are used as planting material. This type of dasheen spoils quickly due to its high water content.

It is grown mainly for local sales and home consumption, as its high perishability and characteristic covering of root hairs make it generally less attractive to exporters and higglers.

POST HARVEST PRACTICES

Harvesting

Dasheen corms should be carefully removed from the soil as even very small scrapes and bruises which break the protective outer skin can become sites of entry of disease organisms and cause the corms to rot after harvest.

Harvesting should be done with a fork being placed far away from the root system so as to prevent damage to the corm. The soil is then loosened and the corm removed from the soil. In most cases the corm is pulled out of the soil by pulling on the aerial shoot. This results in the cormels of suckers breaking off from the corms, leaving large wounds which heal very slowly, and so act as sites of pathogenic infestation.

Harvesting at the right maturity stage is very important as immature corms will posses large cormel scars. Dasheen should be reaped between 7-9 months for wetland type and 9-12 months for dryland type.

Corms with many large scars should not be purchased as these may spoil before being consumed.

Handling practices

Never throw or drop corms during handling. This will result in impact damage which is not seen externally at the same time, but internal bruising will occur, resulting in spoilage.

Never reap corms long before transport is available. Place produce in a cool, shaded environment until transport arrives.

Leaves and cormels should be carefully removed at harvest.

Sacks can be used to remove corms from the field. However, make sure that heat does not build up inside the bags. High temperature and humidity can lead to rapid spoilage.

Do not overload the field containers as this may lead to compression damage.

Storage at ambient temperature of wetland Dasheen may last for 5-10 days.

Simple storage can be done by burying in shaded well-drained leaf-lined soil pits for up to (4) weeks.

Cold storage can further extend the life of the corms to periods of 4-6 months at 10ºC. However, these corms must be clean of soil, dry, and free from mechanical injury.

Post Harvest Diseases

  • Phytophora colocasiae-light brown firm rot, often with a distinct margin
  • Phythium splendes-a white, dry crumbling rot with sharply defined irregular boundary between healthy and decayed tissue.
  • Botyrodiplodia theobrome-a strong smelling rot similar to P. colocasiae initially but rapidly changing to blue-black with age and having a distinct margin.
  • Fusarium solani-a white, dry powdery rot with a distinct margin.

Control

  • This achieved by the use of postharvest chemicals eg. TBZ, Ridomil MBC 60.

Packaging

Dasheen is packaged in moist saw dust in two piece telescopic carton boxes and sea-freighted to its destinations-UK, USA and Canada.

Remember that the corms must be removed quickly out of the field after harvest.

Selecting & Grading

This can take place in the field and at delivery.

In the field:

  • Removal of all rotted, damaged and small or abnormal-shaped corms which may be difficult to handle in processing.
  • All excess soil should be removed.
  • Removal of small suckers from main corm.
  • Corms should have a minimum of 3-4 small sucker-attachment points (scars), but no large scars should be present.
  • Removal of major portion of stalk (cabbage) or leaf bases can take place in the field. However, some should be left on the corm for protection to final destination.
  • Dasheen corms should be fully matured therefore possessing none or few large scars enhancing the shelf-life.

Storage

Corms should be properly cured before storage resulting in the healing of wounds.