Olive leaf spot disease

Disease name: Olive leaf spot English name: Spot Leaf Olive

The scientific name: Spilocaea oleagina

The type of disease: Fungal disease Species: Venturiaceae

Symptoms

1. Olive leaf spot, also known as peacock spot or bird's eye spot, is characterized by the appearance of circular or irregular spots on the leaves of olive trees.
2. These spots are initially small, yellowish-green or yellowish-brown in color, with a dark brown or black center.
3. As the disease progresses, the spots may enlarge and merge, forming larger spots.
4. In severe cases, premature defoliation can occur, resulting in decreased photosynthesis and fruit production.

the reasons

• This disease is caused by the fungus Spilocaea oleagina.
• The fungus ferments in infected leaves on the tree or on the ground and produces spores that can infect new leaves and shoots in spring and summer.

Propagation conditions

• Olive leaf spot disease prefers warm, humid conditions and long periods of leaf moisture.
• Fungus spores are spread by wind, rain, or sprinkler irrigation, allowing them to spread from infected to healthy plants.
• The disease can also be spread by contaminated pruning tools or plant material.
• Factors that promote dense crown growth such as excessive nitrogen fertilization or poor pruning increase the severity of the disease by creating a moist living environment inside the tree.

Losses

• Olive leaf spot can significantly reduce olive yield due to premature defoliation, which hinders photosynthesis and fruit development.
• In severe cases, the disease can weaken the tree and make it more vulnerable to stresses such as drought or pests, eventually causing the tree to decline or die.

Control strategy

• An integrated approach that includes agricultural practices such as pruning to improve ventilation, avoiding excessive nitrogen fertilization, and proper disposal of infected plant residues helps control olive leaf spot.
• Fungicide sprays concurrent with the disease cycle may also be necessary in severe cases.

Preventive measures

• Preventive measures include proper pruning to promote aeration, avoiding overhead sprinkler irrigation, and removing and destroying infected plant material.
• Using olive varieties that are resistant or tolerant to the disease can also help reduce its incidence and severity.

Organic/chemical control

• For organic control, copper-based fungicides, such as copper hydroxide or copper oxychloride, can be used as preventive or pesticide treatments.
• These copper compounds have antimicrobial properties and can help suppress fungal growth.
• Biocontrol agents, such as certain strains of Bacillus subtilis, have also shown promise in reducing the severity of olive leaf spot.

In conventional agriculture, synthetic fungicides such as trifloxystrobin, pyraclostrobin, or difenoconazole may be used for chemical control.