The Olive Leaf Spot: Monitoring, Integrated Management and Environmental Sustainability

Olive Leaf Spot, caused by the fungus, Venturia oleaginea o Spilocaea oleagina represents major challenges facing olive production in Spain. This disease is widely spread throughout our geography and has a direct impact on olive trees, causing significant defoliation and directly affecting the production and quality of olives.

Recognizing Olive Leaf Spot

IIts symptoms are unmistakable: circular or ring-shaped spots that develop mainly on the upper leaf surface, presenting variable sizes and a dark color due to the development of spores. In spring, these spots often exhibit a yellowish halo, facilitating identification. Under unfavorable conditions, especially during the summer season, punctures and atypical spots may appear.

Biological Cycle and Key Conditions

The biological cycle of the fungus depends on specific climatic conditions for its development. Leaf surfaces need to be in contact with water from dew or rain for 1-2 days, and the temperature must remain within the range of 8-24°C, with an optimum around 15°C Therefore, there are geographically susceptible areas to scab development due to the availability of moisture and suitable temperatures.

Addressing the Olive Leaf Spot Challenge

To combat this issue, it is crucial to adopt a comprehensive approach, leveraging both traditional and innovative measures available in the market.

Among traditional measures, proper pruning is an essential pillar. This practice not only improves air circulation by reducing the microclimate conducive to the fungus but also promotes healthy vegetative growth.

Additionally, the careful selection of scab-resistant varieties when establishing new plantations becomes an essential strategy, especially in disease-prone areas. Complementarily, proper soil management, efficient irrigation, and balanced nutrition enhance olive resistance to scab, reducing the need for fungicides.

In the realm of phytosanitary measures, there are various fungicides with different modes of action, including preventive, curative, systemic, and translaminar options, specifically designed to combat scab. Common active ingredients in these products include copper-based compounds, kresoxim-methyl, dodine, difenoconazole, tebuconazole, and trifloxystrobin.

Monitoring, Integrated Management, and New Trends:

Continuous monitoring of climatic conditions and early detection of the fungus’s presence on olive leaves are fundamental, allowing timely and precise application of preventive or curative measures. This minimizes the impact of Leaf Spot and protects the harvest.

Furthermore, it is essential to highlight that with the disappearance of many existing active substances, the complexity of controlling this disease in olive crops has increased. In response to this challenge, promising biological alternatives have emerged, such as biofertilizers based on beneficial microorganisms or plant extracts. These solutions not only strengthen the crop and make it more resistant to diseases and pests but also reduce dependence on chemicals, thus contributing to more environmentally friendly management.

Olive leaf spot spotting remains a constant challenge for olive crops in Spain. However, current trends in managing this disease point towards more sustainable and technologically advanced approaches.
The combination of traditional measures with ecological alternatives, continuous monitoring, and sustainable agronomic practices can significantly contribute to mitigating the effects of scab, ensuring the health of olive trees and the quality of olives in a more sustainable agricultural environment.