Bay leaf tree, or Bay laurel (Laurus nobilis) is a well known garden plant. It is an evergreen shrub or small tree that provides leaves commonly used in cooking to add flavour as a pot herb that is added during cooking and then removed before the dish is eaten. It can also be a useful landscaping plant, and is commonly used in hedgerow or border planting.
Bay can be relatively easy and straightforward to grow. But there are certain problems that can crop up. To help you grow your bay successfully, we’ve come up with this list of common bay leaf tree problems and how to solve them:
First of all, some of the problems that are common when growing bay laurel involve environmental issues. For example, you might see:
Bay plants with their aromatic leaves are a delightful addition to any garden. However, like all plants, they can fall victim to diseases. By learning to identify common bay plant diseases and follow proper treatment methods, you can keep your bay healthy and thriving.
Common Diseases Affecting Bay Plants
Several fungal and bacterial diseases are known to infect bay plants. Here are some of the most frequent culprits:
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Anthracnose – This fungal disease causes leaf spots, blights, cankers, and dieback. On bay leaves, look for small, brown spots that enlarge and turn black. The centers may drop out, leaving shot holes. This disease thrives in warm, wet weather.
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Botryosphaeria Canker – A fungus that infects branches and twigs creating sunken cankers oozing reddish-brown sap. Dieback occurs above the cankers. Prune out infected wood.
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Phytophthora Root Rot – Root and crown rot caused by a soil-borne water mold. Leaves yellow, wilt, and drop. Roots turn brown and mushy. Improve drainage and don’t overwater.
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Armillaria Root Rot – Also called oak root fungus, this disease causes roots and crowns to rot. Foliage yellows and wilts. Clusters of honey-colored mushrooms may grow at base of plant.
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Bacterial Leaf Spot – Angular, water-soaked spots on leaves which later turn brown. Centers fall out, leaving shot holes. Copper sprays can help prevent spread.
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Powdery Mildew – A fungal disease causing a white, powdery coating on leaves. Later leaves yellow wither, and drop. Provide good air circulation and prune to open up canopy.
How to Treat and Prevent Bay Plant Diseases
If your bay plant shows disease symptoms, swift action is required. Here are some tips:
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Remove and destroy infected plant parts immediately to prevent spread.
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Improve air circulation and light penetration by thinning inner branches.
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Water in morning so leaves dry out during the day. Avoid wetting foliage.
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Use drip irrigation and improve drainage if fungus problems persist.
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Apply fungicides containing chlorothalonil, myclobutanil, copper, or sulfur at first sign of disease. Read all labels and follow instructions carefully.
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Treat the soil around plants with fungicides to kill pathogens. Products with trichoderma, streptomycin, metalaxyl help protect roots.
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For bacterial diseases, copper sprays can be applied preventatively when conditions favor infection.
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Solarize the soil prior to planting to kill fungi and other pathogens.
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Mulch well around plants to prevent soil from splashing onto leaves during watering/rain.
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Practice crop rotation if bay is grown in garden beds. Avoid planting bay in same spot for 3+ years.
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Clean up debris from around plants frequently to remove inoculum that can spread disease next season.
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Plant resistant varieties if available. ‘Smaragd’ bay laurel has resistance to leaf spot.
By taking a proactive approach and addressing diseases before they get out of hand, you can continue enjoying robust, productive bay plants for years to come. Be on the lookout for early symptoms, and don’t hesitate to intervene at first sign of infection. A timely fungicide drench or diligent pruning is much easier than losing plants or producing poor quality leaves. With knowledge and vigilance, you can stay one step ahead of whatever fungi or bacteria come your way.
Identifying Specific Bay Plant Diseases
To determine the best course of treatment, it’s important to accurately diagnose which disease is causing problems for your bay plant. Here’s an in-depth guide to identifying some common bay diseases:
Anthracnose
Caused by the fungus Colletotrichum
Symptoms
- Small, brown, irregular spots on leaves
- Spots enlarge and turn black in center
- Centers of spots fall out, leaving “shot holes”
- Most severe in warm, rainy weather
- Defoliation
- Dieback of branches
Treatment
- Improve air circulation
- Remove and destroy fallen leaves
- Apply fungicide (chlorothalonil, copper) at first sign
Phytophthora Root Rot
Caused by the fungus Phytophthora
Symptoms
- Leaves wilt, turn yellow, drop off
- Roots and crown turn brown/black and rot
- White fungal growth on base of stem
- Occurs in wet, poorly-drained soil
Treatment
- Improve drainage immediately
- Apply fungicide drench (metalaxyl)
- Remove and destroy affected plants
Bacterial Leaf Spot
Caused by the bacterium Xanthomonas campestris
Symptoms
- Small, water-soaked spots on leaves
- Spots enlarge, centers die and fall out
- Leaves turn yellow and drop
- Defoliation of plant
- Most common during warm, wet weather
Treatment
- Prune out infected leaves/stems
- Apply copper spray as a protectant
- Avoid overhead watering
Armillaria Root Rot
Caused by the fungus Armillaria mellea
Symptoms
- Main roots rot, turn dark brown
- Foliage yellows, wilts, dies back
- Clusters of honey-colored mushrooms at base
- Bark peels back on stem near soil line
Treatment
- Remove and destroy affected plants
- Apply fungicide drench (propiconazole)
- Improve drainage
Accurate identification is key before attempting to treat a plant disease. If you’re unsure what’s affecting your bay, have a sample diagnosed by your local county extension office. Once you know the culprit, you can take action to eradicate it and protect your remaining plants.
When to Call a Professional
For home gardeners, basic disease prevention and management is usually sufficient to protect bay plants. However, if diseases persist and worsen despite your best efforts, it may be wise to enlist professional help. Consider calling an arborist, horticulturist, or pest control company if:
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Disease rapidly spreads to multiple plants
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Fungicides and treatments don’t seem to work
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Leaves, branches, or entire plants quickly decline
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You need help identifying the disease
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Large portions of the plant show severe symptoms
The sooner specialists can diagnose and treat rampant diseases, the better chance your bay plant has of survival. Professionals have commercial-grade products, specialized equipment, and experience dealing with severe or stubborn plant health issues. If DIY methods fail to remedy the problem, don’t wait – call in an expert right away to get your bay back on track.
Growing healthy, productive bay plants requires vigilance against diseases like anthracnose, root rots, leaf spots, and mildews. Inspect plants frequently and address issues promptly. Remove infected material, improve growing conditions, apply fungicides/bactericides, and call in professionals if needed. Know what diseases are prevalent in your area and take action at first signs. With quick identification and treatment, you can keep your bay foliage glossy and abundant for cooking, crafting, and aesthetic enjoyment.
Disease Problems in Bay Leaf Tree
If environmental conditions have not been ideal for your bay leaf tree, then disease is more likely to take hold. In order to decrease the chances of a pathogenic problem, make sure that you keep your plants ‘happy’ and as free from stress as possible.
Bay leaf trees are generally not troubled by disease all that often. But Phytophthora root rot is one thing that can affect these plants. This fungus-like organism can infect your bay tree and cause weakness and slow collapse. As with most diseases, prevention is better than cure. Make sure you eliminate problems with weak drainage and that you have placed you bay in a suitable spot.
If this disease has already taken hold, you may be able to save your tree by removing the soil from all around the tree, cutting away any dark or oozing bark, and leaving the root system exposed to dry, which can slow the spread of this infection.
Plant Diseases and Disorders – Julie Beale
FAQ
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