Plant Pandemics

Why in news?

Plant pandemics have been forecasted as the next big contagion and posing threats to global food security.

What is Plant pandemic?

• Plant pandemic - It is the disease outbreak that spreads across continents or subcontinents and causes mass mortality in plants.

What are the factors driving plant pandemics?

• Climate Change – With the consequent expansion of warmer and more humid conditions to higher latitudes, tropical diseases are spreading to temperate and higher latitudes.
• Higher global trade - Introduction of foreign crops and flow of agricultural produces across the globe enables the pathogens to spread across the globe favouring disease outbreak
  • In the 1980s, citrus plants infected by Citrus tristeza virus were shipped in vast numbers to unaffected countries, leading to a large-scale infestation and extending the pandemic.
• Increased industrial Farming – Large scale mono cropping pattern facilitates the quick spread of the pathogen across the field.
  • High-density monocultures soybean and wheat are compromised by the fungus Phakopsora pachyrhizi.
  • Wheat blotch caused by the fungus Zymoseptoria tritici.

What are the impacts of plant pandemic?

• It could provoke a humanitarian crisis that could deprive people of livelihood and lead to widespread hunger.
• Threats global food security – Plant pandemics affects the yields of diverse food crops and cause food shortage across the globe
  • Yield losses of more than 50% have been documented during severe epidemics.

Fungal disease outbreak could reduce global wheat production by 13% by 2050.

• Famine – Plant pandemics causes famine and large-scale death
  • 1943 Bengal famine - Caused by Cochliobolus miyabeanus, a brown spot disease in rice led to the death of over 2 million people.
• Loss of Livelihood – Farmers lose their livelihood and are pushed to poverty.
• Promote out migration – Loss of crops causes farmers and people to migrate to other regions for food and livelihood.
  • Between 1845 and 1852, Phytophthora infestans wiped out potato crops in Ireland, resulting in famine & mass migration.
• Damage ecosystem – Pathogen outbreak disrupts the natural food web and ecosystem functions.

Pierce’s disease is a bacterial disease that affects grapevines and can cause epidemics in vineyards of southern Europe, particularly in France, Italy and Portugal.

What are the challenges in controlling plant pandemic?

• Ineffective fungicides – Existing fungicides are ineffective in controlling these newly evolved pathogens.
• Increasing resistance – High usage of fungicides is making the pathogens like Magnaporthe oryzae Triticum to develop higher resistance to those fungicides.

Magnaporthe oryzae Triticum (MoT), a fungus that attacks wheat crops and can wipe out the entire harvest in a matter of days.

• Complexity pathogen – Physiological and genetical complexity of the pathogens makes it difficult to understand their interaction with the target crops.
  • For example, in case of MoT fungal infection, there is difficulty in deciphering the gene responsible in MoT or in wheat that confer durable resistance to it.
• Evolution - Pathogens are evolving fast to reproduce quickly infect new hosts.
• As the fungus spreads to wider geographies, it may evolve to become more virulent or infect other species.
• Inter species spread – Some pathogens could jump to other crops.
  • For instance, pathogens may jump from wheat to paddy.

What lies ahead?

• Diversify crops to limit the outbreak and yield loss.
• Create genetic libraries of crops and pathogens to mitigate the future risk.
• Screen seeds and certify them for the fungus and quarantine measures to help thwart its spread to other countries.
• Model the global food system using advanced technologies like data analytics to forecast the disease outbreak in plants.
• Implement a greater disease surveillance by improved detection.

References

1. Down To Earth| Magnaporthe oryzae Triticum Infection across Ind0-Bangladesh Border
2. Down To Earth | Plant Diseases – Causes, Origin and Impacts
3. Down To Earth| Efforts to be taken to control Plant Pandemic