Citrus Psorosis: A Damaging Disease for Citrus Trees
What is Citrus Psorosis?
Citrus psorosis is a contagious viral disease that affects citrus trees worldwide, particularly in major citrus-producing regions like North and South America and the Mediterranean. This disease has multiple strains, and while some are more severe than others, all will eventually impact the tree’s health and productivity. Fortunately, the prevalence of citrus psorosis has decreased in recent years thanks to the use of certified disease-free budwood in grafting.
Symptoms of Citrus Psorosis
Citrus psorosis primarily affects citrus trees that are at least eight to 10 years old. Symptoms include:
- Bark: Patches of bark with small blisters or pustules, which eventually develop into scaly patches or slough away. Gummy lesions may also form on or under the bark.
- Leaves: Young leaves may exhibit mottling and yellow flecks, which often fade as the season progresses.
- Fruit: Infected citrus fruit is inedible and may have a mottled appearance or depressed, grayish or yellowish rings.
Causes of Citrus Psorosis
Citrus psorosis is a viral disease that is primarily spread through grafts of infected budwood. It can also be transmitted through contaminated grafting tools or, in some types of citrus, through infected seeds.
Preventing Citrus Psorosis
The most effective way to prevent citrus psorosis is to:
- Purchase certified disease-free trees or budwood from reputable nurseries.
- Ensure that grafting tools are sanitized regularly to avoid contamination.
Treating Citrus Psorosis
Unfortunately, there is no cure for citrus psorosis. Treatment options are limited and may only provide temporary relief:
- Scraping away infected bark: This can help stimulate the growth of a callus over the wound, but it will not eliminate the virus.
- Replacing diseased trees: In severe cases, it may be necessary to replace infected trees with healthy ones.
Impact of Citrus Psorosis
Citrus psorosis can significantly impact citrus trees and the citrus industry as a whole:
- Reduced productivity: Infected trees produce less fruit, which leads to economic losses for growers.
- Fruit quality: Infected fruit is often inedible or of poor quality, further reducing its value.
- Spread of the disease: Infected trees can spread the virus to other trees in the grove, leading to widespread outbreaks.
Research and Management
Ongoing research is being conducted to develop new management strategies for citrus psorosis. Current recommendations for managing the disease include:
- Using certified disease-free planting material.
- Sanitizing grafting tools.
- Removing and destroying infected trees.
- Implementing quarantine measures to prevent the spread of the disease.
By following these practices, citrus growers can help minimize the impact of citrus psorosis on their trees and the citrus industry.
