Citrus Leaf Spot: Symptoms, Prevention and Control

Citrus spot , also known as black spot, is a fungal disease that seriously threatens citrus production. Caused by the fungus Phyllosticta citricarpa (formerly Guignardia citricarpa ), it mainly affects leaves and fruits, reducing their commercial quality. At Agrumiverse , your citrus plant supplier and citrus plant wholesaler , we help you understand and prevent this disease to protect your crops.

Symptoms of Citrus Leaf Spot

Citrus spot symptoms appear mainly on the leaves and fruits of citrus trees. The most characteristic signs are:

On the leaves:

• Circular spots: Appearance of punctiform spots visible on both sides of the leaves, with a dark brown to black center surrounded by a yellow halo.
• Evolution of spots: Over time, the spots turn gray or light brown, compromising the health of the leaves.

On fruits:

• Hard spots: Fruits develop hard spots 3–10 mm in diameter, with a gray to brown center and a dark brown to black border.
• Halos around lesions: In some cases, yellow or green halos may appear around the spots.
• Freckles: Presence of small concave spots of 1 to 3 mm on the surface of the fruit.
• Deep lesions: In advanced cases, deep, irregular lesions can cause premature fruit drop, significantly reducing the harvest.

Citrus Species Affected by Citrus Leaf Spot

Citrus leaf spot can affect several species of citrus fruits, some being more sensitive than others:

Very sensitive:

• Lemon tree (Citrus limon): The lemon tree is the species most susceptible to this disease.
• Orange (Citrus sinensis): Oranges, especially late varieties like Valencia, are very vulnerable to citrus leaf spot.

Moderately sensitive:

• Mandarin tree (Citrus reticulata)
• Grapefruit (Citrus paradisi)

Other species concerned:

• Kumquat (Fortunella): Kumquats can also be affected by Phyllosticta citricarpa .

It is important to note that black spot disease has not yet been observed in the Mediterranean basin. However, the importation of infected fruit and propagation material could introduce this pathogen into Europe, threatening local crops.

Prophylaxis and Control of Citrus Spot

Citrus spot control relies on preventative measures and rigorous cultural practices. Here are some key recommendations to prevent the onset of this disease:

Cultural practices:

• Irrigation: Use ground irrigation rather than sprinkler irrigation to minimize moisture on leaves and fruit.
• Windbreaks: Install windbreaks around and inside orchards to protect trees from humid drafts.
• Pruning: Prune trees regularly to promote better air circulation and adequate sunlight, thus reducing the conditions favorable to the spread of the fungus.

Treatments:

Although there are no widely recommended specific treatments for citrus leaf spot, an integrated approach including general fungicide treatments, combined with rigorous cultural practices, can be effective.

• Monitoring: If citrus spot is suspected, contact local plant health authorities immediately for an accurate diagnosis.

Important Points to Remember

• Severity: Citrus spot is a serious fungal disease that can reduce the commercial quality of citrus fruits.
• Crucial prevention: Adopting preventative cultural practices is essential to limit the impact of this disease.
• Integrated Approach: A combination of preventative measures and regular monitoring is necessary to protect your orchards from this potential threat. At Agrumiverse , we offer a wide range of healthy citrus plants from certified nurseries to help reduce the risk of fungal disease spread.

FAQ

What are the main symptoms of citrus spot?

The main symptoms include the appearance of circular spots on the leaves, hard spots on the fruits with a gray to brown center surrounded by a dark border, and, in advanced cases, deep lesions on the fruits which can cause premature drop.

Which citrus species are most affected by citrus leaf spot?

Lemon and orange trees are most susceptible to this disease, while mandarin, grapefruit and kumquat trees are moderately affected.

How to prevent citrus leaf spot in a citrus orchard?

It is recommended to favor ground irrigation rather than sprinklers, install windbreaks to protect trees, and prune regularly to improve air circulation. Agrumiverse can advise you on the best cultural management practices to prevent this disease.

Are there any specific treatments for citrus stain?

Available sources do not mention specific treatments for citrus leaf spot. However, it is recommended to adopt an integrated approach using preventive practices and to contact plant protection authorities if the disease is suspected.

Why is it important to monitor orchards for citrus leaf spot?

Regular monitoring of orchards allows early detection of signs of the disease and immediate measures to be taken to limit the spread of the fungus, thus avoiding heavy economic losses.

How can Agrumiverse help prevent citrus fungal diseases?

Agrumiverse , as a supplier for professional citrus growers , offers certified, healthy and resistant citrus plants , as well as personalized technical advice to ensure the health and longevity of your orchards.