Disease name: Lemon stubbornness disease
Scientific name: Spiroplasma citri
Type of disease: bacterial
Disease family: Spiroplasmataceae
(A part of the lemon tree was infected with the stubborn disease)
- The causes of disease:
The disease is caused by bacteria that do not have a cell wall and live in the phloem sieve tubes of infected lemon plants. The bacteria multiply in leafhoppers, which are considered the carrier of this disease. Symptoms continue to appear even after treating the infected trees, hence the disease’s name.
- Symptoms of the disease:
The similarity of the symptoms of this disease to other diseases makes it difficult to detect in the field, so laboratory testing is required. One of the most important visual symptoms is the small size of the leaves and their straight growth. Old trees may not show any symptoms, while others or part of the tree may have them. It shows symptoms, as the disease does not spread well within the tree, and flowering can occur out of season, which may lead to the appearance of fruits of uneven maturity on the affected tree or part of the tree. The lemon fruits that are produced are likely to be small and unbalanced and may It has a bitter flavour, and the seeds found in lemon fruits fall off.
(Seeds falling into lemon fruits as a result of infection with Spiroplasma citri bacteria)
- Disease development cycle:
Analysis shows that bacteria are transferred primarily from weeds to lemon plants and secondarily from one lemon plant to another. After conducting laboratory tests based on culturing bacteria from plant or reproductive tissues, the results take 2 to 3 weeks. Therefore, it is recommended to perform a PCR test that is more sensitive than the traditional method because It can detect bacteria in a sample at low concentrations.
- Conditions suitable for the spread of the disease:
Hot and dry weather helps the development and spread of Spiroplasma citri bacteria, as they settle in warm indoor growing areas. They may be found in humid environments, but their presence is minimal, as they require a temperature ranging between (25 - 30) degrees Celsius.
Bacteria (Spiroplasma citri
- Losses resulting from the spread of the disease:
Disease is more of a problem in young orchards than in mature orchards. Stunted growth and reduced lemon production will usually continue throughout the life of the tree, but older trees often have low production and drop fruit.
- Control:
Graft the infected plant with healthy shoots and use shoots and grafting materials that are free of pathogens.
Remove infected trees and replant them with disease-free trees.
Proper use of tetracycline may be useful in treating the disease.
- preventive measures:
Obtain seedlings from an area free of disease.
Weed control in and around the lemon field.
Sterilize agricultural tools constantly to avoid transmission of the disease from one field to another or plant to another.
Follow up on the crop if any unusual symptoms or signs appear.
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