At last, Panama Disease in banana can be controlled
  
Plant pathology.
Stimulation of natural defence mechanisms.
 
Panama Disease

Panama Disease is the name given to wilting caused by the fungus Fusarium oxysporum f.sp. cubense. It is one of the most serious threats worldwide to banana crops and causes large economic losses. This pathogen, which attacks the roots and invades the vascular system of of the banana plant, hinders its normal feeding and causes progressive dehydration, yellowing of the leaves, wilting and, finally, the death of the plant.

 

Use of pesticides

Over the past fifty years, the use of pesticides in farming to control pests and pathogens has contributed, on the one hand, to harming the environment and, on the other, to a deterioration of the quality of agricultural products due to their content in toxic waste.

The classic approach in the battle against plant diseases has been to remove or counteract the pathogen as far as possible by means of the said pesticides, ignoring the fact that the plant has its own defence mechanisms. Why not stimulate them? This scarcely explored possibility has, however, given place to the development of so-called resistance inducers.

This type of chemical products, which are generally non-toxic, induce biochemical processes in the plant that considerably augment the capacity of the plant to defend itself with respect to untreated plants.

Thus, among other common plant defence responses, such substances induce the plant cells to biosynthesize a certain amount of defence antibiotics (known as phytoalexins), in a manner similar to genetically resistant plants, and to create physical barriers that impede penetration of the pathogen.

 

New compounds

PARAM-A: A series of compounds that are innocuous to humans, animals, plants and the environment, which, under field conditions, have been proven to be efficient against Panama Disease in banana plants. Chemical control of this disease was hitherto impossible. Crop production and quality of pretreated plots has increased by 30% with respect to untreated plots.

It has been determined that plants pretreated with these compounds biosynthesize different amounts of defence antibiotics (phytoalexins) than the control banana plants, when submitted to inoculation under identical experimental conditions. It must be stressed that these substances do not spontaneously induce the synthesis of defence antibiotics but rather they subtly increase the concentration of phytoalexins at the precise site and moment in which the plant is attacked by the invading fungus during the development of pathogenesis. What really happens is that the plants pretreated with these natural compounds mimic the model of incompatible (resistant) banana plant-fungus interaction.

 

Considering that this type of compounds do not act against the pathogen directly but through the plant, strengthening its defences, research is underway in order to verify their efficacy in other plant-parasite systems, very promising results having been obtained in preliminary experiments carried out in several different crops.

Unlike pesticides, this type of non-contaminating substances are destined to play an important role in agriculture for years to come.