Wheat Blast

• Context (DTE): Recent study established concerning link between climate change and wheat blast.
• Currently, it affects 6.4 million hectares of cropland globally.
• By 2050, climate change is projected to exacerbate the situation, putting 13.5 million hectares of cropland at risk.

Wheat Blast (WB)

• It is a fungal disease caused by the pathogen Magnaporthe oryzae pathotype Triticum (MoT).
• It was first identified in Brazil in 1985.
• It is a fast-acting and devastating disease that poses a significant threat to wheat crops, particularly in tropical and subtropical regions.

Symptoms

• Progressive bleaching of heads, where infected spikes show a silvery appearance with a green canopy, turning partially or fully bleached in severe cases.
• Infected plants exhibit discoloured stems and leave with dark brown lesions and visible dark grey fungal spores.

How does it spread?

• It spreads via infected seeds, posing threat to new crops as the fungus can persist within them.
• Airborne spores are key in wheat blast transmission, travelling long distances and swiftly infecting nearby wheat fields upon release.
• Infected crop residues containing the fungus aid in disease spread by surviving and infecting new plants under favourable conditions.
• Warmer temperatures and prolonged leaf moisture aid wheat blast pathogen spread, fostering disease growth.
• Also, international wheat trade has been a cause in some countries like Bangladesh and Zambia.

Implications

• It leads to significant yield reductions, with projections indicating a potential 13% global wheat production decrease.
  • Vulnerable regions like South America and Africa could face up to 75% of their wheat acreage at risk by 2050.
• WB can incur significant economic losses in certain countries.
  • Vulnerable wheat-growing regions in Bangladesh, India, and Pakistan could incur potential losses of 886 thousand metric tons of wheat production, amounting to USD 132 million annually.
  • E.g. During the 2016 outbreak, an estimated total wheat production loss of approximately 8,205 tons, worth USD 2.1 million, was recorded.
• The spread of WB poses a threat to global food security, particularly in regions experiencing growing wheat consumption.

Way Forward

• Develop and promote wheat varieties resistant to WB.
• Combine race non-specific resistance genes to enhance durability.
• Fungicide spray applications can help manage WB.
• Strictly regulate the movement of contaminated plant material and farm equipment.
• Implement practices to break the disease cycle.
• Properly manage crop residues to reduce disease transmission.
• Use early warning systems to predict disease outbreaks.
• Investigate biological control agents to suppress WB (Beneficial microorganisms or natural enemies can play a role).