Cocoa swollen bud virus disease It is one of the most economically damaging cocoa tree diseases, accounting for almost 15-50% of crop losses in Ghana. This virus is transmitted when several species of mealybugs feed on cocoa plants.
A cacao tree with cacao fruit attached directly to the trunk or branches.Image credit: Gamera other., doi: 10.1094/PDIS-10-22-2412-FE.
Cocoa swollen shoot virus disease (CSSVD) first observed Infected by farmers in the eastern region of Ghana in 1936, the nature of the virus was identified in 1939.
CSSVD is considered the most economically damaging cocoa virus disease and can cause yield losses of 15-50% when severe strains are involved in infection.
Cocoa swollen shoot virus (CSSV) is classified as a member of the plant-infecting pararetroviruses of the genus Cocoa swollen shoot virus. badnavirus It contains nonenveloped rod-like particles that encapsulate a circular double-stranded DNA genome.
Previously, isolates and strains were grouped according to severity of symptom onset and geographic origin.
CSSVD is currently known to be caused by the following causes: complex of badnavirus seed Based on molecular structure.
CSSV affects all parts of the cocoa plant. Symptoms seen on leaves include red vein stripes on immature “flush” leaves, green-green vein spots or stripes that can occur in angular spots, removal of green-green veins, and various shapes Includes mosaic symptoms.
The virus causes swelling of the stem (nodes, internodes, tips) and roots.
In some strains, the infected pods change shape, becoming rounder and smaller and with a smoother surface.
“This virus is a real threat to the world's chocolate supply,” said Professor Benito Chen Charpentier, a researcher at the University of Texas at Arlington.
“Pesticides are ineffective against mealybugs, so farmers try to prevent the spread of the disease by cutting down infected trees or breeding resistant trees. However, Ghana has lost more than 254 million cocoa trees in recent years.
Farmers can combat mealybugs by vaccinating trees with CSSV. But vaccines are expensive, especially for low-wage farmers, and vaccinated trees produce less cocoa, making the damage caused by the virus even worse.
Electron micrograph of swollen shoot virus particles in purified cocoa. Scale bar – 200 nm.Image credit: Gamera other., doi: 10.1094/PDIS-10-22-2412-FE.
Professor Chen Charpentier and colleagues have developed a new strategy. Use mathematical data to determine how far apart farmers can plant vaccinated trees to prevent mealybugs from jumping from one tree to another and spreading the virus That's what it is.
“Mealybugs have several ways of getting around, including moving from canopy to canopy, being carried by ants, and being blown by the wind,” Professor Chen Charpentier said.
“What we needed to do was create a model for cocoa farmers to vaccinate unvaccinated trees to prevent the spread of the virus while making costs more manageable for smallholders. The goal was to be able to know how far away a tree could be safely planted.”
By experimenting with mathematical patterning techniques, the authors create two different types of models that allow farmers to create a protective layer of vaccinated cocoa trees around unvaccinated trees. Did.
“Although still experimental, these models are exciting because they can help farmers protect their crops while achieving better yields,” said Professor Chen Charpentier.
“It’s good for farmers’ bottom lines and it’s good for the world’s chocolate addiction.”
a paper The findings were published online in the journal PLoS ONE.
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FB Agusto other. 2024. Cocoa Sustainability: The Case of Cocoa Swollen Bud Virus Co-infection. PLoS ONE 19 (3): e0294579; doi: 10.1371/journal.pone.0294579
Source: www.sci.news
