the reasons
Lemon peel is caused by the fungal pathogen Elsinoë fawcettii. The fungus can survive in infected plant debris such as fallen leaves and branches, as well as the surface of fruit and soil. Mushroom spores are spread by wind, rain or splashing water.
Favorable conditions for spread
Lemon peel spreads in warm, humid conditions with frequent periods of rainfall or sprinkler irrigation. The optimum temperature for disease development is between 20 and 30°C, with a relative humidity of more than 70%. Heavy dew, frequent rain or sprinkler irrigation can create favorable conditions for fungal growth and infection.
Disease course
The lemon peel disease cycle begins with the formation of pathogenic fungi in infected plant remains or on the surface of fruits. During periods of warm, humid weather, the fungus produces spores that are spread by wind, rain or splashing water. These spores can infect young and tender fruits, leaves and branches. Once infection occurs, the fungus penetrates the plant tissue and causes lesions to form. As the lesions mature, they develop a rough, cracked surface, which can release more spores that can spread to other parts of the plant or to nearby trees. The disease cycle continues as long as favorable environmental conditions persist and susceptible plant tissue is available. The fungus can survive in plant debris or on the surface of fruits, providing sources of infection for future seasons.
Losses
Lemon peeling can lead to significant economic losses due to reduced fruit quality and marketability. Severely infected fruits are often unmarketable due to their unattractive appearance and potential for rot. In addition, the disease can weaken trees, making them more susceptible to diseases and other environmental stressors, and may lead to lower yields.
Control strategies
Strategies to control lemon peel include the use of fungicides, proper orchard hygiene practices, and selecting resistant or tolerant varieties. Fungicide spraying must be timed to protect fruits during their susceptible period to the disease. Cultural practices such as pruning to improve airflow and removing infected plant debris can also help reduce disease pressure.
Preventive measures
Preventive measures for lemon peel include using disease-free seedlings, maintaining proper spacing between plants, pruning to improve air circulation, avoiding sprinkler irrigation or spraying under high pressure during humid periods, and removing and destroying infected plant material. Regular surveying and monitoring for early detection of symptoms are also very important, as well as maintaining proper plant nutrition and carrying out fungicide spraying when necessary.
Organic/chemical control
Organic control measures include the use of biocontrol agents such as Bacillus subtilis or Trichoderma harzianum, which can suppress the growth of fungal pathogens. In addition, plant extracts such as neem oil or garlic extracts, or copper-based fungicides can provide some protection against the disease. Regarding chemical control, synthetic fungicides such as dimethyl growth inhibitors (DMIs) such as difenoconazole or propiconazole, strobilurin compounds such as pyraclostrobin or trifloxystrobin, or copper-based fungicides can be used. Fungicide sprays to protect fruit should be timed during periods of high disease risk, such as during warm, humid conditions or after heavy rain. The use of fungicides with different mechanisms of action should be alternated to prevent the emergence of resistance.
the reviewer:
Timmer, L. W., Biever, D. L., Soliel, Z., & Akiyama, K. (2003). Fungal citrus diseases: New disease syndromes. Phytopathologia Mediterranea, 42(2), 99-112. https://www.yarden.com/citrus-tree-care/pests-diseases
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