In the Eye of the Storm
Each sip from a cup of tea or coffee tells a story. However, the journey to the cup has become increasingly difficult, with unpredictable twists and turns threatening crops. The environmental challenges confronting tea and coffee are not novel. However, they have become more volatile,
requiring producers to consider long-term strategies to address them.
“Twenty years ago, farmers could tell you exactly the date when it was going to rain, but
that is no longer the case, which means that the quality of harvests are also unpredictable,” said
Jan Dellwisch, tea department and supervisor, organic division, Kloth & Köhnken Teehandel,
Bremen-Europahafen, Germany. “There are many biological phenomena which are highly unpredictable, coupled with political instability; tea buying has never been associated with so many risks.”
Producers must cope with climate unpredictability and a volatile market, including roadblocks within the supply chain preventing them from obtaining imported solutions like pesticides and fertilizers. Using fertilizers can help insulate plants from environmental stressors by improving the overall resiliency of the plants. However, access to fertilizer, particularly potash, which primarily comes from Russia, has become increasingly challenging, with some suppliers restricting access.
“The actual impact of this supply challenge is still unclear, but certain countries that previously relied heavily on fertilizers have been struggling with fulfilling their supply,” said Hanna Neuschwander, director of strategy and communications, World Coffee Research. “Other countries where the cultural norm is not to use fertilizers will be less impacted by this challenge.”
As imported resources, like fertilizers, become increasingly more challenging to access, farmers are
beginning to look for local alternatives to nourish their harvest and build their plants’ resiliency. The
strategies may include integrating resistant strains, applying pesticides, or putting the foundation in
place for integrated pest management.
As a buyer, Dellwisch shared that diversification, buying tea from a variety of origins, has become
a necessary strategy. Currently, the company is working with suppliers in Africa for their green
tea to provide another source outside of Asia. “As traders and suppliers to many international brand
owners, we have to decide which purchase path we are going to take,” said Dellwisch. “The path that
we’ve chosen is that we are not going to restrict ourselves to single estates because of the risks; we
are going to use a variety of sources to maintain availability and the quality of our product.”
Enhancing the plants’ resiliency has become increasingly critical as the volatility of biological
challenges continues to escalate. Regenerative agriculture, specifically improving soil health,
continues to gain attention as producers look at developing an environment that can aid plants
in combatting pathogens. “Farming extracts so much energy out of the soil, and it is not always being properly reapplied, which means that the quality of the soil is becoming poorer and poorer,” said Dellwisch. “In the long term, organic farming will mitigate the risk; the soil is much more fertile, and the plants are healthier, which means that they will be better equipped to resist outside threats. However, in the short term, we do not have the specific answer.”
One avenue that tea and coffee researchers are investigating is whether there are biological
pathogens that can be integrated at the farm level to combat these challenges. Studies, such as the
one sponsored by the World Coffee Research (WCR) in 2014, have identified natural enemies to pathogens. The WCR survey, which took place in Brazil, identified several mycoparasites; one in particular, Calonectria hemileiae, appeared to promote defense responses against rust when applied to coffee plants.
Brazilian researchers at the Federal University of Vicosa, Brazil, also looked at biological pathogens to rust, specifically whether the hexane extract, from the medicinal plant Garcina gardneriana, which is known for its antimicrobial activity, could potentially be used as a natural antifungal product against coffee leaf rust. Although the research is still in its infancy, these biological solutions may help insulate the plants from the catastrophic damage that coffee leaf rust can cause.
Understanding the genetics of the pathogens themselves may also help researchers determine the best method to combat them. Dr Catherine Aime, a mycologist from Purdue University, specialises in fungi that cause rust disease, and is currently tracing the genome. The team has already identified the aggressive strain of coffee leaf rust impacting Hawaii.
“The ultimate goal is to provide the knowledge, based on genomic and population analyses, about
how the rust manages to erode host resistance so quickly,” said Aime in a recent article published
by Alliance for Science. “Once this is understood, then we can better plan strategies to mitigate
outbreaks, whether that involves changes in management, or breeding strategies. Rust fungi cause some of our most serious diseases of agricultural crops and forest products. So, any insights into how they overcome host resistance may help to inform strategies to control them in other systems.”
In tea, researchers are studying several pathogens, including identifying the whole genome in teal leaf spot to determine its evolution to develop solutions to combat it. The fact that tea is often grown as a monoculture crop increases its risk for pathogens and pests. Pathogens like blister blight, previously only seen in the tropical provinces, have expanded into the subtropical regions in China. Tea’s natural defense mechanisms, including caffeine and catechin levels, decrease when tea is grown at higher temperatures. Introducing grasses and shade trees, like the Guatemala grass, is one strategy that is being used in Sri Lanka and India to help develop a more resilient environment.
The Role of Research
Research has played a critical role in providing both tea and coffee producers with strategies to help minimise the negative impact from pathogens. Strategies include data analysis and implementing technology to help detect the threat before it reaches catastrophic levels. These tools can be used to track both weather patterns and pathogens while also providing a way to connect with local producers to help prevent the pathogen from spreading.
Research in Central America and Hawaii has been focused on developing early detection systems for coffee leaf rust, which includes studying the relationship between meteorological conditions and the rust epidemic. Hawaiian researchers Luis Aristizabal and Melissa Johnson launched a monitoring program in Kona to assist growers with the early detection of coffee leaf rust to determine the patterns of the disease in the region.
Weather-based disease forecasting models and remote sensing techniques have also been developed to respond to the challenge of blister blight in Sri Lanka, India and Indonesia. However, forecasting systems are not enough to address the challenges that tea faces. Dr Abhay Pandey, mycologist, Tea Research Association, India, emphasised that detailed multi-seasonal field trials are required at both nursery and field levels to identify resistance sources against major diseases of tea plants, including using this data to develop climate-resilient tea cultivars.
Integrating resilient strains continues to be a proactive solution for farmers across the globe. The most recent coffee strain that has been drawing attention is RAB C15, a varietal that was originally introduced in 2015. The variety was released after eight years of field testing and experiments to determine its resilience against coffee leaf rust and coffee berry borer disease, and how well it adapted to the environmental conditions of Rwanda. World Coffee Research reports that this varietal is a tall, high-yielding varietal that is both rust and coffee berry disease resistant. It has been gaining interest from
farmers in Kenya, Uganda, and Rwanda to see if it could potentially alleviate the stress of coffee berry disease.
The challenge is that over time, the strains that were once resistant will no longer be so, and so new varietals must be continually researched and produced. World Coffee Research is launching a new global breeding program to provide supply partners with germplasm. “Modern genetics allows us to look inside the genes and identify the good combinations which will be the ones that we will cross, with the hope that additional learnings from the crops will reduce the amount of time it takes for new varieties to be put into the market,” said Neuschwander.
The plants will be grown in multiple coffee-growing regions, exposing the strains to a range of environmental variabilities while also allowing farmers to better predict if the strain will respond well to the evolving climate in their region. Neuschwander shared that the response to the upcoming program has been extremely positive and is hopeful that the program will be up and running, including secured partnerships and field sites, by early 2024.
The harsh truth is that biological challenges show no sign of dissipating; however, the solutions to address these challenges are evolving. Farmers are implementing long-term strategies, including
increasing the diversity of vegetation on the farm, focusing on soil health, introducing resilient strains, and integrating predictive technology to prevent outbreaks. These strategies will continue to evolve as knowledge about the environment and the challenges that we face grow.
By Anne-Marie Hardie