Witches broom is a plant disease that affects many trees and crops worldwide. The disease is characterized by the abnormal growth of branches, resulting in clusters of smaller branches, similar in appearance to a broom. The disease has been around for centuries and has impacted agriculture and forestry worldwide.
The earliest recorded case of this disease dates back to the 18th century in Germany, where it was observed on blackthorn bushes. The disease spread rapidly to other plants, and by the 20th century, it had spread worldwide, affecting various tree species such as cacao, citrus, and coffee.
Moreover, it is widespread in tropical and subtropical regions worldwide. The disease is prevalent in countries such as Brazil, Venezuela, Colombia, Ghana, Nigeria, Indonesia, and the Ivory Coast. The disease affects different tree species depending on the country and region. For example, this disease is a significant problem in the cocoa industry in West Africa and South America, while in Asia, the disease affects rubber trees.
However, it continues to be a significant threat to agriculture and forestry worldwide, with estimated losses of up to $700 million annually. The disease has a severe impact on the livelihoods of farmers and the global economy. In Brazil, for example, it has caused a 70% reduction in cocoa production, leading to a significant impact on the country’s economy. According to recent statistics, this disease is responsible for a 30-40% reduction in coffee production in Brazil, the world’s largest coffee producer.
According to a report by the Food and Agriculture Organization (FAO), witches broom disease affects various crops worldwide, including cocoa, coffee, rubber, and citrus, leading to annual losses of up to US$2 billion. The report also states that it has caused significant economic losses in several countries, including Brazil, Colombia, Costa Rica, Indonesia, and Malaysia. In Brazil, for example, the annual losses due to this disease in the cacao industry alone are estimated to be around US$500 million. In Colombia, the disease has led to a reduction in coffee yields by up to 80%, leading to a significant impact on the country’s economy.
It is caused by various pathogens such as fungi, bacteria, and viruses. Recent scientific evidence has shown that the pathogen responsible for this disease in cacao is a fungus called Moniliophthora perniciosa. The fungus infects the cacao tree through wounds on the bark or flowers, resulting in the formation of broom clusters.
This disease has significant economic and social importance. The disease affects various tree species worldwide, leading to reduced yields, smaller fruits, and eventual death of the tree. The disease has a severe impact on the livelihoods of farmers and the global economy. For example, the loss of cocoa production due to this disease has affected the economies of several West African countries, leading to a reduction in the income of farmers and the loss of jobs.
For example, a study by Alvarado and colleagues (2021) found that the incidence of cacao witches broom disease in Central America is strongly influenced by temperature and rainfall patterns. The study suggests that climate change may lead to an increase in the disease’s incidence in the region, leading to significant economic losses for farmers. Another study by Bisseleua and colleagues (2018) found that climate change can also affect the distribution and severity of coffee broom disease in Africa.
This disease has numerous effects, depending on the tree species affected. The most common effects include:
- Reduced yield – the disease reduces the number of fruits produced, resulting in lower yields.
- Smaller fruits – the disease causes the fruits to be smaller, affecting their quality and market value.
- Death of the tree – severe infections can lead to the death of the tree, leading to the loss of income for farmers and the global economy.
Furthermore, the pathogen responsible for the disease varies depending on the tree species affected. For example, Moniliophthora perniciosa is the fungus responsible for this disease in cacao, while the bacterium Xylella fastidiosa causes citrus witches broom.
The disease can be transmitted through different means such as insect vectors, wind, or human activity. The pathogen enters the tree through wounds on the bark, leaves, or flowers, leading to the formation of broom clusters. The disease can also spread rapidly from an infected tree to nearby trees, leading to the spread of the disease within a farm or forest.
There are various types of witches broom disease depending on the tree species affected. The most common types include:
- Cacao witches broom – This type affects the cacao tree, leading to stunted growth, deformed pods, and a reduction in yield. It is caused by the fungus Moniliophthora perniciosa. The disease affects the cacao tree’s reproductive structures, leading to a significant impact on the cocoa industry.
- Coffee broom – This type affects coffee trees, leading to smaller berries, reduced yield, and eventual death of the tree. It is caused by the fungus Gibberella xylarioides. The disease affects the growth and productivity of the coffee tree, leading to significant economic losses for coffee-producing countries.
- Citrus witches broom – This type affects citrus trees, causing abnormal growth and reduced fruit production. It is caused by the bacterium Xylella fastidiosa. The disease is a significant threat to the citrus industry worldwide, leading to significant economic losses for farmers and the global economy.
- Rubber broom – This affects rubber trees, causing the tree to produce small and weak latex vessels. It is caused by the fungus Microcyclus ulei. The disease affects the quality and yield of rubber, leading to significant economic losses for rubber-producing countries.
However, its management involves a combination of measures such as sanitation, chemical control, and biological control. Sanitation involves the removal and destruction of infected trees and plant debris to prevent the spread of the disease. Chemical control involves the use of fungicides, bactericides, and insecticides to control the pathogen responsible for the disease. Biological control involves the use of beneficial microorganisms such as fungi and bacteria to control the pathogen responsible for this disease.
Further, several factors contribute to its spread, such as climate change, deforestation, and the global movement of goods and people. Climate change can lead to changes in temperature and rainfall patterns, creating favorable conditions for the pathogen responsible for the disease. Deforestation can lead to the loss of habitat for natural enemies of the pathogen, leading to an increase in the disease’s spread.
Additionally, deforestation can also create conditions that favor the spread of the pathogen, as it can lead to changes in microclimate, soil nutrients, and water availability. The global movement of goods and people can also contribute to its spread, as infected plant material and insect vectors can be transported to new locations, leading to the introduction of the disease to new areas.
In conclusion, Witches broom disease is a significant threat to the global economy, particularly in developing countries. The disease can lead to a reduction in yield, smaller fruits, and eventual death of the tree, leading to significant economic losses for farmers and the global economy. Climate change, deforestation, and the global movement of goods and people are some of the factors that contribute to the spread of this disease. While several measures such as sanitation, chemical control, and biological control are available, none of them can completely eradicate the disease.