The outbreak of X-disease in cherry orchards in the Northwest has drawn research attention to the once little-known grasshopper Colladonus reductus. Although several grasshopper species can carry the phytoplasma of disease X, C. reductus accounts for most of the vector activity in Washington State.
Washington State University pathologist Scott Harper highlighted the ability of C. reductus to transmit strain 3, which is more aggressive in spreading due to pathogen/vector compatibility. This discovery is one of many emerging as scientists seek to understand the pathogen/vector complex in order to develop sustainable management strategies for disease X.
The goal is to develop an IPM approach, as WSU entomologist Tobin Northfield explains. They are working on phenological models to optimise pest management strategies in orchards, making them less attractive to leafhoppers, rather than relying on prophylactic spraying that could cause resistance.
Currently, more than a dozen research projects, funded with $1.6 million in federal grants and $540,000 in grants from the Washington and Oregon cherry industry, are underway.
Scientists have discovered that the transmission of phytoplasma by grasshoppers takes a different time than previously estimated. Adrian Marshall, a postdoctoral researcher at the US Department of Agriculture laboratory in Wapato, Washington, conducted a study that revealed that 50 per cent of grasshoppers were able to transmit X-disease by day 17 after force-feeding.
Marshall suggests removing super-infected trees to keep grasshopper levels low, highlighting the importance of understanding the dynamics of transmission under different conditions. Removing root suckers has been shown to reduce the risk of X-disease transmission. Removing broadleaf weeds and the use of herbicides are recommended to make ground cover less attractive to grasshoppers.
Researchers are also exploring potential biocontrols, including the use of large-headed flies and pincer wasps that parasitise grasshoppers. Eliminating weeds, such as dandelion and mallow, may reduce the risk of disease X in orchards. Genetic studies on grasshoppers and phytoplasma offer interesting perspectives. Identifying key genes could pave the way for new approaches, such as the use of biopesticides or gene silencing techniques.
The fight against X-disease involves a combination of strategies to reduce the density of locusts and remove infected trees. By reducing the percentage of harmful trees, scientists hope to eliminate phytoplasmas from the system, solving the grasshopper problem.
Read the full article: Good Fruit Grower
Image: Good Fruit Grower
23 Jan 2025
For the American tart cherry industry, this statement is a sweet nod to the versatility of the fruit among younger generations. From adventurous culinary creations to its vibrant ruby-red beauty, tart cherries are set to inspire a new audience in unexpected ways.
07 Mar 2025
The study day on 19 February 2025 was an opportunity to update technicians and producers on the effectiveness of the control methods currently implemented and the prospects offered by the application of biological control.
29 Jul 2026
UPA-UCE and Asaja urge the Extremadura government to launch an emergency plan for cherry growers in northern Cáceres after storms caused losses above €20 million, destroyed harvests, cut farm income below production costs and exposed major gaps in crop insurance today.
29 Jul 2026
In the United Kingdom, BeeSAM2 combines artificial intelligence and computer vision to detect bee visits to cherry blossoms with high accuracy, reducing manual analysis while improving research into pollination, fruit set, crop stability and orchard productivity.
