Even hardy olive trees can encounter a few problems. If you notice your olive tree looking less than perfect – perhaps olive tree leaves turning yellow, or pests lurking on the foliage – don’t worry. Here we address some common Arbequina olive tree issues and how to solve them, so your tree stays healthy and happy.
Yellow Leaves on Olive Trees
Problem: Olive tree leaves are turning yellow and dropping off.
Possible Causes:
- Natural Leaf Shedding: Olives are evergreen, but they do shed older leaves. It’s normal for an olive tree (especially in spring) to drop some of its oldest leaves, which turn yellow then brown as they age. If the yellow leaves are mostly interior (older) ones and the rest of the foliage looks healthy, this may just be the tree’s natural cycle.
- Overwatering / Poor Drainage: Too much water can lead to yellow leaves. Olive roots need oxygen; if soil is constantly wet or drains poorly, roots can start to suffocate or rot. This often shows up as generalized yellowing, sometimes with leaf drop and a wilted appearance.
- Underwatering / Drought Stress: On the flip side, prolonged drought can cause olive leaves to yellow or brown around the edges and eventually drop. However, olives tolerate drought fairly well, so this is less common unless the tree is neglected.
- Nutrient Deficiency: A lack of nutrients, especially nitrogen, can cause leaves to be pale yellow-green. Iron deficiency (in high pH soil) causes interveinal chlorosis – leaves turn yellow but the veins stay green.
Solutions:
- First, assess your watering. Feel the soil: if it’s sopping wet and heavy, ease up on watering and improve drainage (for a potted tree, ensure drain holes are clear; for in-ground, consider amending soil or planting on a mound). If soil is bone dry, give your olive a slow, deep drink and monitor if new leaves stay green.
- For suspected overwatering, you might also remove any mulch that could be keeping soil too wet and let the topsoil dry out a bit. Ensure the pot or planting spot isn’t in a low spot that collects water.
- If nutrient deficiency is suspected (uniform pale color), consider a balanced fertilizer application in spring. If iron chlorosis is evident (yellow with green veins), you can treat the soil or foliage with chelated iron according to package directions.
- Remember, if only a few older leaves are yellow but new growth is fine, the tree may just be renewing its foliage. In that case, simply prune off any truly dead twigs or unsightly yellow leaves and carry on with normal care.
Pest Problems on Olive Trees
Problem: Pests are visible on the olive tree or causing damage (spots on leaves, sticky residue, etc.).
Common Olive Tree Pests:
- Scale Insects: These pests look like small brown or gray bumps stuck on stems and the undersides of leaves. They suck sap and excrete sticky “honeydew,” which can make leaves shiny/sticky and lead to sooty mold growth.
- Aphids: Tiny green, black, or brown soft-bodied insects that cluster on new growth and leaf undersides. They also produce honeydew and can cause curling/distorted new leaves.
- Spider Mites: Very small reddish or brown mites that aren’t easily seen with the naked eye, but you might notice fine webbing on leaves and a speckled, pale look to the foliage.
- Olive Fruit Fly: A notorious olive pest (if you are trying to fruit your tree). The adult is a small fly that lays eggs in the olive; larvae tunnel in the fruit, ruining it. This doesn’t typically harm the tree’s health, but it destroys the olives.
Solutions:
- For scale and aphids, a gentle approach is to spray the tree with a strong jet of water to knock many off. Follow that by applying insecticidal soap or horticultural oil to affected areas. Coat the undersides of leaves and stems where pests are present. Repeat weekly for a few applications to catch any hatchlings. These treatments suffocate soft-bodied insects and are safe for Arbequinas (avoid spraying in extreme heat or sun to prevent leaf burn).
- For spider mites, first hose off the foliage (mites thrive in dry, dusty conditions). Increase humidity around the tree if possible (spritz it, or for indoor trees, run a humidifier). Use insecticidal soap on the leaves, making sure to get the undersides. Two or three rounds of treatment a week apart should greatly reduce mites.
- For olive fruit flies (if fruiting): Use yellow sticky traps hung in the tree to monitor and catch adult flies. If you see evidence of larvae in fallen fruit, promptly gather and dispose of all dropped olives (do not compost) to break the life cycle. In areas where fruit fly is common, some growers bag individual fruit or use kaolin clay spray as a repellant. As a home gardener, if fruit flies are heavy, you might focus on curing green olives (harvest before the flies lay eggs) or simply grow the tree as an ornamental and not let the fruit mature.
- Maintaining overall tree health via proper watering and feeding makes it less vulnerable to pests. Also, inspect your olive tree regularly – catching a small aphid colony early, for instance, makes control much easier before they multiply.
Other Issues and Their Remedies
- Sooty Black Coating on Leaves: This is likely sooty mold fungus growing on sticky honeydew left by pests (like scale or aphids). By controlling the pest (as above), the sooty mold will gradually weather off. You can gently wipe leaves with a damp cloth to remove the black coating if desired.
- Fungal Leaf Spots: In humid or rainy climates, olives can get fungal spots like Peacock Spot (dark circular spots on leaves). If your tree has a lot of spotted, dropping leaves in winter, you can spray a copper-based fungicide in late fall as a preventative. Ensure good airflow through pruning. Usually, olive leaf spot diseases don’t kill the tree but may cause it to drop some leaves; new growth will come in clean if the issue is addressed.
- Overall Lack of Vigor: If your Arbequina just isn’t thriving – little growth, pale leaves, etc. – reconsider its light exposure and soil. Olives want lots of sun; move it to a sunnier spot if possible. Make sure it’s not overwatered. A spring dose of fertilizer can kick-start growth. Also check that it isn’t rootbound if in a pot – it may need a larger container or root pruning and fresh soil if it’s been many years in the same pot.
Keeping Your Olive Tree Healthy
Many olive tree problems can be solved with proper basic care:
- Sunlight: Ensure your tree gets enough light (at least 6 hours of direct sun daily).
- Water: Water deeply but infrequently, and always allow drainage. Adjust based on weather – less in cool seasons, more in hot dry periods.
- Soil & Nutrients: Provide well-draining soil and feed lightly in spring and early summer. Correct any obvious deficiencies.
- Cleanliness: Remove fallen leaves and fruit, which can harbor pests or disease. If you had a pest outbreak, clean around the base of the tree to remove any eggs or spores that might be on dropped debris.
- Observation: Spend a moment each week to glance over your olive tree. Early signs of issues (a few yellow leaves, a cluster of aphids) can be dealt with before they become big problems.
Arbequina olive trees are quite resilient. By troubleshooting issues like yellow leaves or pest infestations with the tips above, you can keep your olive tree in great shape. Soon, it will reward you with vigorous growth – and perhaps a handsome crop of olives – once any problems are resolved. Happy growing!