Coffee Wilt Disease | UPSC

      HEADLINES:

Researchers re-animate 70-year-old coffee killer fungus in Africa: Study

      WHY IN NEWS:

  • Researchers have re-animated 70-year-old frozen samples of fungus to look for modern-day clues that cause coffee to wilt.
  • The study, published in journal BMC Genomics June 4, 2021, showed how historical genomics can help reveal mechanisms that prevent fungal pathogens from spreading.
SYLLABUS COVERED: GS 3:Diseases

      ISSUE: 

COFFEE WILT DISEASE

  • Coffee is a major cash crop, with over 2.5 million people directly depending on its production and trade as a livelihood.
  • For some countries, coffee accounts for 50% of primary foreign exchange, valued around 300–400 million dollars annually.

BACKGROUND

  • The first outbreak in the 1920s-1950s was brought under control by management practices such as burning infected trees, looking for natural resistance in coffee and breeding programmes.
  • However, the disease re-emerged in the 1970s; it spread extensively through the 1990s and 2000s. It continues to cause damage in 2021.

CAUSES

  • It currently affects two of Africa’s most popular coffee varieties — Arabica coffee in Ethiopia and Robusta coffee in east and central Africa.

Coffee Wilt Disease | UPSC

SOURCES : DOWNTOEARTH

MANAGEMENT

  • Once a coffee plant is infected by coffee wilt disease, death is inevitable, making prevention the most beneficial for coffee growers.

  • Additionally, regular root inspections are an effective measure to catch the disease in the early stages.
  • Once disease is found, destruction of the coffee plant by cutting it at the ground level and burning it stops the spread of the infection to other plants.
  • Restriction of movement for coffee plant, coffee husks mulch and planting materials are also useful.

DISEASE CYCLE

  • The fungal pathogen responsible for coffee wilt disease can exist on coffee trees as Gibberella xylarioides, the sexual or perfect stage, or as Fusarium xylarioides, the asexual or imperfect stage.

Coffee wilt disease is spread by wind-born ascospores during its sexual stage or splash-borne conidia, where they land and can persist as a viable source of inoculum in the soil.

  • Infection occurs via penetration of wounds at the base of stems, mainly by the imperfect stage Fusarium xylarioides.
  • Once the plant is infected, the fungus blocks the xylem system, which induces host responses that inevitably result in plant death.

HOST

Hosts of coffee wilt disease include Coffea arabica (Arabica coffee), Coffea canephora (Robusta coffee), Coffea liberica (Liberian coffee), and Coffea excelsa (Excelsa coffee)

  • Currently, the disease is limited to Eastern and Central Africa, however, studies have shown that most Coffea species are likely to be susceptible to the disease, which can potentially lead to more worldwide problems in the coffee industry.

SYMPTOMS AND SIGNS

  • Due to the nature of coffee wilt disease, coffee plants often exhibit symptoms of disruption to vascular systems.

Internal symptoms are disturbances to conduction of water in the plant.

  • External symptoms include loss of moisture on leaves, discolouration, leaf loss, dieback of the infected region, swelling of trunks, cracks in mature trees and lastly plant death.
  • Signs of coffee wilt disease include small blackish-brown perithecia caused by the sexual stage of the fungus, and cracks in the bark which cause an observable bluish-black stain on the wood.

RECENT FINDINGS

  • The research team noticed that the two species often live close to the roots of coffee and banana plants, so it was possible that coffee fungus gained these genes from banana-based neighbours.

The researchers are now using the re-animated strains to infect coffee plants in the laboratory to study how the fungus infects the plant.

  • This may help understand other ways to prevent the disease from occurring.
  • The historical approach shows us what happens to a plant pathogen before and after a new outbreak of disease occurs.
  • We can then study the mechanisms of evolution and improve predictions of how similar outbreaks could occur in the future.
  • The discovery could help farmers reduce the risk of emerging new disease strains. For example, coffee beans could be planted separately from other crops.
  • Farmers could also work to prevent the accumulation of plant waste that can shelter the associated fungus.

      IASbhai WINDUP: 

  • Relocation of coffee production or replanting of resistant C. canephora germplasm, assist with combating future spread.

Preventive measures for coffee wilt disease infection are to avoid wounding of trees for example when removing control weeds, fertilizing soil or by grazing of any animals.

  • Additionally, maintaining plants’ health by using inorganic fertilizer, manure or mulch to conserve moisture are some ways to decrease the risk of coffee wilt disease.
     SOURCES:  DownToEarth  | Coffee Wilt Disease | UPSC

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