Common Olive Tree Plant Diseases:
How to Identify and Treat

Olive trees are not only beautiful additions to any landscape, but they also provide delicious fruits and high-quality olive oil. However, like any other plant, olive trees are susceptible to various diseases that can affect their growth and overall health. In this article, we will explore some common olive tree plant diseases, how to identify them, and the best treatments to keep your olive trees thriving.

1. Olive Knot Disease

One of the most prevalent diseases affecting olive trees is the Olive Knot disease, caused by the bacterium Pseudomonas savastanoi. This disease manifests as small, rough galls or knots on the branches, twigs, and trunks of the tree. These knots can vary in size from a few millimeters to several centimeters in diameter and can be greenish or brownish in color.

To identify Olive Knot disease, inspect your olive tree for these knots. If you notice any irregular swellings or bumpy growths on the branches, it is likely that your tree is infected. It is crucial to act promptly to prevent further damage.

The best treatment for Olive Knot disease is to prune and remove all the affected parts of the tree. Be sure to disinfect your pruning tools after each cut with a solution of one part bleach to nine parts water to avoid spreading the bacteria. Additionally, applying copper-based fungicides during late winter or early spring can help control the disease.

2. Verticillium Wilt

Another common disease that affects olive trees is Verticillium Wilt, caused by soil-borne fungi of the Verticillium genus. This disease usually occurs during periods of high soil moisture and can lead to severe damage or even death of the tree if left untreated.

The symptoms of Verticillium Wilt include wilting leaves that turn yellow or brown, starting from the lower branches and moving upwards. The leaves may also exhibit necrotic areas or yellowing veins. To confirm the presence of Verticillium Wilt, look for dark streaks in the sapwood of affected branches.

Unfortunately, there is no cure for Verticillium Wilt once a tree is infected. However, there are several management practices that can help control the disease. Firstly, avoid planting olive trees in soil known to be infested with Verticillium fungi. Additionally, maintaining proper soil drainage and avoiding overwatering can help prevent the disease from spreading. If you suspect Verticillium Wilt in your olive tree, it is best to remove and destroy the infected tree to prevent further contamination.

3. Peacock Spot

Peacock Spot, caused by the fungus Spilocaea oleagina, is another common disease that affects olive trees. This disease primarily affects the leaves, causing circular or irregularly shaped spots that range in color from light green to dark brown or black. These spots may have a yellow halo around them and can merge as the infection progresses.

To identify Peacock Spot, examine the leaves of your olive tree for these characteristic spots. If you notice any discoloration or unusual markings on the foliage, it is likely that your tree is infected.

To treat Peacock Spot, it is important to maintain good orchard hygiene by removing fallen leaves and pruning any dense foliage that restricts air circulation. Applying copper-based fungicides during late winter or early spring can also help control the disease. Be sure to follow the instructions on the fungicide label for safe and effective application.

4. Olive Leaf Spot

Olive Leaf Spot, caused by the fungus Spilocea oleagina, is a disease that affects both young and mature olive trees. It is characterized by small, round or elongated spots on the leaves that appear as yellow or brown lesions with dark borders. These spots can merge and cause premature defoliation if left untreated.

To identify Olive Leaf Spot, inspect the leaves of your olive tree for these characteristic spots. If you notice any discoloration or irregular markings on the foliage, it is likely that your tree is infected.

The best treatment for Olive Leaf Spot is to maintain good orchard hygiene by removing fallen leaves and pruning any dense foliage. Applying copper-based fungicides during late winter or early spring can also help control the disease. Be sure to follow the instructions on the fungicide label for safe and effective application.

Conclusion

Keeping your olive trees healthy and disease-free requires vigilance and proper care. By learning to identify common diseases such as Olive Knot disease, Verticillium Wilt, Peacock Spot, and Olive Leaf Spot, you can take early action to prevent further damage and ensure the longevity of your olive trees. Remember to practice good orchard hygiene, prune affected parts, and apply appropriate fungicides when necessary. With proper care, your olive trees will continue to thrive and provide you with delicious olives for years to come.