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- Malady Mystery #2
Hello Robigalia Reader and welcome back to another week of Robigalia, delivering the latest in plant pathology directly to your inbox.
In this week’s edition, we’re diving into a mystery disease that has gained the name Moria, which translates to “die-off”. It also happens to be the name of the ill-fated mines from The Lord of the Rings (which certianly caught my attention). Keep scrolling to find out which plant is impacted by this mystery disease. If you’re a Robigalia subscriber you can also access my online database and listen to today’s title song!
Despite its deceiving name, kiwifruit (Actinidia spp.) is a vine-growing berry native to China that began cultivation in New Zealand in the early 20th century. Today, kiwifruit is also grown in Europe and the Middle East. Until recently, Italy was the second-largest producer of kiwifruit globally. Unfortunately, the emergence of Kiwifruit Vine Decline Syndrome (KVDS) is challenging this global position.
KVDS was first detected in the Veneto region of Italy in 2012. Since its initial discovery, the syndrome has had a devastating impact on Italy's kiwifruit industry. It is estimated to affect over 25% of the total cultivation area, representing approximately 6,160 hectares of kiwifruit orchards. In these areas, up to 80% of the plants have been impacted by KVDS. Despite the impact of KVDS, the exact cause of the syndrome remains a mystery. However, recent studies have linked a combination of various pathogens and waterlogging to the syndrome.
KVDS is characterised by several symptoms that lead to the rapid decline and death of kiwifruit vines. The syndrome impacts both the above-ground and below-ground parts of the vine. The early symptoms include yellowing of leaves, with affected vines exhibiting chlorosis, particularly in the lower leaves. As the disease progresses, wilting becomes more pronounced, particularly during hot weather. Underground, examination of the roots reveals brown, decayed, and mushy roots.
After its initial detection in Veneto, KVDS quickly spread to other major kiwifruit cultivation areas including Lazio, Piedmont, Emilia Romagna, and Calabria. With the kiwifruit industry in Italy generating over 400 million euros annually, KVDS causes massive increases in orchard operating costs and substantial economic losses for farmers. As a result of the increasing costs and challenges of KVDS management, in severely affected areas like Verona, farmers have started to abandon kiwifruit fields.
The impact of KVDS has been so significant that the Italian government has formed a task force to study the syndrome. Despite extensive research, the exact cause remains elusive, with scientists suspecting a complex interaction of factors, including water management, soil conditions, pathogens, and possibly climate change. This mysterious syndrome has put the entire global kiwifruit industry on alert. Countries like New Zealand are closely monitoring the situation to prevent potential spread to their orchards.
If you’re interested in learning about some of the potential causative agents of KVDS, read the published literature below!
Kiwifruit Vine Decline Syndrome papers
Characterization of Phytopythium Species Involved in the Establishment and Development of Kiwifruit Vine Decline Syndrome
This study identified multiple Phytopythium species as key contributors to Kiwifruit Vine Decline Syndrome (KVDS) in Italy, with P. litorale and P. helicoides being reported for the first time. These findings highlight the complex interplay of pathogens and environmental factors, underscoring the need for integrated management strategies to combat this significant threat to kiwifruit production.
This study highlights that sustainable agronomic practices, such as precision irrigation and organic matter addition, significantly mitigate kiwifruit vine decline syndrome (KVDS). By improving soil aeration and reducing waterlogging, these methods not only enhance soil health but also decrease the prevalence of pathogenic fungi, leading to a 46% increase in healthy plants.
This study shows the genetic diversity of Actinidia species significantly influences the composition of oomycete communities in the root zones. Resistant genotypes, such as A. macrosperma and A. arguta, were found to harbour beneficial oomycetes like Globisporangium intermedium, which may help suppress the more pathogenic Phytophthora species prevalent in susceptible genotypes. These findings suggest using resistant Actinidia species in breeding programs could be a promising strategy to manage KVDS and mitigate its economic impact.
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Until next week,
Alyssa
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