Diversity & resilience
Diversity of coconut (© Roland Bourdeix CC BY-NC-ND 4.0)
Strength in diversity!
Some varieties of coconut are more vulnerable to diseases, pests and other forms of damage than others. Growing a diversity of coconut varieties ensures that the crop is not affected as much as if one variety alone is planted.
Considering diversity is likely to become even more important because:
Diversity can be considered in terms of the varieties of coconut planted, as well as the other different crops that are planted with coconut.
Tolerance is the ability of a particular plant (or plant variety) to avoid, endure or recover from attacks by insects or diseases or climate variability than other varieties of plants of the same species. In agricultural systems, tolerance means that despite stress from a pest or disease, the production levels can remain above an economic threshold.
Resistance means that a plant completely resists the effects of a given pest or disease.
Both tolerance and resistance conditions along a continuum: from plant types very susceptible to those that are completely unsusceptible.
For a grower, resistant types are preferable to tolerant types, which in turn, are preferable to susceptible types.
For pest and disease mitigation, one less costly and time-consuming way is to use resistant or tolerant varieties. This requires that consistent breeding programmes are set up and succeed to identify and distribute such tolerant varieties. Sometimes networks and mutual aid between farmers can also help to identify and obtain such varieties directly from farmer’s fields.
Ideally replanting programmes should focus in tolerant / resistant varieties. In reality, different varieties have different uses so replanting is often dictated by the farmers product. Discussing options with farmers and listening to their needs also is important in these cases.
The table below outlines some of the vulnerable (susceptible) and resistant or tolerant varieties of coconut to specific pests and diseases.
The suggestions below are based on information from different locations. Check with your local Agriculture department for confirmation of the best varieties in your area.
Pest / disease
Disease-resistant / tolerant varieties
|Coconut rhinoceros beetle - Oryctes rhinoceros||Malayan Red Dwarf x Rennell in Papua New Guinea.||-||-|
|Coconut foliar decay||Most varieties introduced to Vanuatu. Malayan Red Dwarf is one of the most susceptible varieties.||Vanuatu Tall (resistant) or Vanuatu Red Dwarf (tolerant).||Rennell Tall.|
|Tinangaja||-||Javanica(?) Red Dwarf.||-|
|Bogia Coconut Syndrome||-||Diverse coconut plantations may limit effects of disease.||-|
|Coconut hispine beetle - Brontispa||Malayan Dwarf and Rennell Tall.||Samoa: Green Dwarf variety of unknown origin.
Solomon Islands: selected Ivory Coast and Fiji varieties.
Pohnpei: Local Tall varieties are resistant.
|Local Tall and Rennell varieties more resistant than Red or Yellow Malayan Dwarf.|
|Coconut mite||Jamaica and Panama Tall, Malayan - Golden, Green and Yellow Dwarf.||Equatorial Green, Malayan and Cameroon Red Dwarfs and Polynesian and Rennell Tall more tolerant.||-|
|Lethal yellowing - and potentially other Phytoplasma diseases||Jamaica Tall, Panama Tall, Malayan Dwarf, Maypan hybrids.||Chowghat Green Dwarf, Cuban Dwarf, Fiji Dwarf, Red Spicata Dwarf, Sri Lanka Yellow Dwarf and King possibly resistant to some Phytoplasma diseases.||-|
|Coconut spike moth||Phillipines: female flowers of 3 to 5-year old Malayan Dwarf x West African Tall hybrids.||-||-|
|Bud rot caused by Phytophthora palmivora||Malayan Yellow, Red and Green Dwarf, Brazilian Green Dwarf, and PB121 Hybrid varieties.||Hybrids of Dwarf crossed with Polynesian Tall and Rennell Tall are said to have better tolerance than the PB121 Hybrid.||-|
|Melanesian CRB||Slower growing palms such as Rennell Tall, Rennell Tall X or Malayan Dwarf.||Papua New Guinea and Solomon Islands: fewer deaths of Gazelle Tall palms.||-|
|Coconut embryo rot||Hybrids with Malayan Dwarf female parents.||Local Tall varieties.||-|
|Coconut leaf spot||Malayan Dwarf and its hybrids.||-||-|
|Sugarcane weevil borer||Varieties with growth cracks.||Varieties with hard rinds and higher fibre.||-|
|Coconut leaf stripe||Malayan Dwarf and hybrid Malayan Dwarf x Rennell.||-||-|
Resistance or tolerance to a pathogen is unlikely to be permanent. In most cases, the pathogens will evolve in order to overcome the existing genetic tolerance or resistance. For annual crops, It seems that the resistance of a variety to a pathogen has, on average, a lifespan of only 15 to 25 years. After this delay, the variety is generally no more resistant because the pathogen has evolved.
We can extrapolate this situation to coconut. There is good reason to think that if, today, we plant a resistant palm, there is a high probability that before its natural death, this coconut palm will become susceptible to new forms of pathogens that will appear. This is why, even if a good and tolerant variety is found, research to find the next good variety should never stop. This is the only way to mitigate the evolution of the pathogens.
Many countries have field genebanks of coconut varieties. When managing these genebanks it is important that hybridisation is controlled. For example, hybridisation should be managed in a laboratory context, rather than allowing genebank trees to hybridise freely in the field.
Refer to the Coconut Field Genebank Guidelines (page 91) for information on effectively managing these genebank resources.
Consideration of diversity is not limited only to the variety of coconut grown. Intercropping, rather than monoculture is the traditional way of farming in the Pacific.
An example of how intercropping can be used is the planting of cocoa together with coconut to minimise coconut stick insect damage.
You can find much more information on the importance of coconut diversity and how to achieve it in Roland Bourdeix's blogs including:
- replanting coconut: CIRAD (French Agricultural Research for Development) created this website on coconut planting material in the Pacific region.
- the polymotu concept of planting: Polymotu is a new research and development concept in multi functional management. It intends to use small islands, valleys or other geographically isolated locations for the conservation of biodiversity of various species, including the coconut palm.
Please see individual pest / disease pages for more information sources.
content reviewed by Roland Bourdeix, CIRAD, October 2018; Jimmy Risimeri and Eremas Tade, Kokonas Indastri Koporesen, Papua New Guinea, October 2018; Renwick Weilbacher, Federated States of Micronesia Quarantine Services, October 2018; Maja Poschko, Cook Islands Ministry of Agriculture, October 2018.