Options for protection from diseases

Disease resistance

The terminology used to qualify the resistance of oil palm varieties differs depending on whether it is being described by a plant pathologist, a breeder, a trader, or a grower. ISF (International Seed Federation) has proposed a clear terminology of the different levels of planting material resistance, which we have chosen to adopt.

Biotic and abiotic resistance

Biotic interactions

The reaction of a plant to a parasite or a disease is highly complex and depends on three factors:

1. Environmental conditions, which can be more or less conducive to the development of the disease or the parasite, its maintenance, etc. (and likewise for the plant).

2. The characteristics of the pest, its aggression strategies, its genetic variability, etc.

3. The plant and its ability to develop its own defence mechanisms.

Oil palms do not all react in the same way to a parasite or a disease. They may react differently depending on the environmental conditions in which they are growing, their age, and the virulence and aggressiveness of the pathogen to which they are exposed. In addition, pests may mutate and develop new races or new strains, which can modify the reaction of palms in a given place.

Abiotic interactions

Oil palms also react differently to abiotic factors, such as pedoclimatic conditions (soil “quality”, temperature, rainfall, sunlight). In this case, the term used to describe the better adaptation of palms to a given abiotic condition is tolerance.

Definition of biotic resistance

• Immunity:

This is usually acquired by way of a specific interaction, gene to gene. Some varieties express total resistance to a pest, without any symptoms. No such resistance systems are known in the oil palm.

• Quantitative resistance or partial resistance:

This is the ability of the oil palm to limit the growth and development of a specified pest and/or the damage it causes compared to a susceptible palm under similar environmental conditions and pest pressure.

  • High resistance:

Ability of the oil palm to greatly restrict the growth and development of a specified pest and/or the damage it causes compared to susceptible palm under normal pest pressure conditions. However, a highly resistant palm may still exhibit some symptoms or damage under heavy pest or disease pressure.

  • Intermediate resistance:

Ability of the oil palm to restrict the growth and development of a specified pest, but exhibiting more symptoms than those of a highly resistant palm under the same conditions. Compared to a susceptible palm under the same conditions, palms with intermediate resistance show fewer symptoms and less damage.

• Susceptibility:

The inability of an oil palm to restrict the growth and development of a specified pest.