Recently, researchers from the University of Tsukuba and Ibaraki University published a research paper, revealing that coffee leaf rust (CLR) disease “is widespread in the main coffee-growing regions of Vietnam, the world’s second-largest coffee producer.” They published their findings in Frontiers in Plant Science.
Coffee leaf rust or Hemileia vastatrix, is one of the most serious coffee tree diseases that has spread to all coffee-growing areas of the world. Major disease outbreaks in Asia, Africa and the Americas have reduced bean quality and continue to cause severe yield losses, in some cases as much as 70%. The disease is caused by a fungus and can be “recognised by yellow powdery spots on the underside of the leaves.”
The study’s objective was to study the genetics of the fungus and see if that would lead them toward the original source. They also wanted to identify migration pathways.
One of the best ways to avoid the disease is to grow rust-resistant variants, although, even in this situation, research has identified cases of infection. “Coffee leaf rust spreads mainly by wind, but human beings can also spread it when they walk into the farm, and the fungus sticks to their clothes and body, just like powder.”
Professor Izumi Okane, the co-author of the study, is aware of the necessity of understanding the role of diversity in solving the problem:
The diversity of the rust population to control this disease.Professor Izumi Okane
Professor Okane also said that identifying the genetic variations that favour rust can help predict future differences.
The researchers studied the occurrence of the CLR disease in major coffee-growing areas of Vietnam, “assessed the current population structure and genetic diversity of the CLR fungus via genetic sequencing, and estimated the geographic region where the disease was first established, as well as its direction of migration between Vietnam’s main coffee-producing areas.”
The research results showed that coffee leaf rust is highly prevalent in most of the regions studied and that H. vastatrix populations in Vietnam have a close genetic relationship with several Central and South American populations.” The study also identified possible starting points and migration routes of coffee leaf rust in Vietnamese coffee-growing regions.
The spread of the disease from northern to southern Vietnam revealed that agents other than wind and monsoon were involved in moving spores from an infected region to other areas.Frontiers | Incidence of Coffee Leaf Rust in Vietnam, Possible Original Sources and Subsequent Pathways of Migration | Plant Science (frontiersin.org)
The results of this study have shed light on the genetic diversity of Hemileia vastatrix and provided new information on genetic diversity in Vietnam and Central and South America. “The researchers’ findings will help predict the spread of this fungus in the future. Furthermore, seedling sources and human activities have been highlighted as factors that should be considered in the coffee-growing industry for the control of CLR disease.”