Most types of holly plants are normally very resilient. All holly plants, however, are susceptible to a few holly problems. One of those problems is holly leaf spot, also known as holly tar spot. This holly disease can kill the leaves off of a holly bush, so keep an eye out for it.
If you’ve noticed the leaves on your holly bushes turning yellow and developing unsightly black spots, it likely signals a fungal disease known as Anthracnose. This fungal infection can spread quickly, causing significant defoliation and an overall unhealthy appearance The good news is that with prompt treatment and adjustments to care, you can get your holly bushes bouncing back. Let’s look at how to identify, treat, and prevent Anthracnose on hollies
Recognizing the Symptoms
The first indication of Anthracnose is small, circular black spots appearing on the leaves. Often there will be tiny black fungal fruiting bodies visible within these spots. As the infection progresses, the spots enlarge and may blend together to form big blotchy lesions. A defining symptom is the yellow halo that surrounds the dead black areas. This yellow ring is the distressed tissue around the advancing infection. Eventually the spots can encompass most of the leaf surface, causing it to turn entirely yellow and drop off.
Understanding the Causes
Anthracnose is caused by the fungus Colletotrichum gloeosporioides Spores spread by wind and rain, infecting new foliage It thrives in warm, humid conditions with prolonged leaf wetness. Slow drying leaves after rains or heavy dews provide optimum conditions. Poor air circulation and dense growth also promote fungal spread. Environmental stress weakens plants, making them more vulnerable to infection.
Implementing Prevention Measures
The best way to prevent Anthracnose is through proactive care and cultural practices:
- Prune for open shape and airflow
- Space plants appropriately
- Remove fallen leaves promptly
- Avoid excessive nitrogen fertilization
- Use drip irrigation instead of overhead watering
- Water early in the day so leaves dry quicker
- Thin inner branches and foliage to enhance air circulation
Also monitor for early symptoms and treat promptly before the infection becomes advanced.
Using Organic Fungicidal Sprays
If Anthracnose is detected early while spots are still small and localized, organic fungicidal sprays may be effective in slowing the spread. Options include:
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Neem oil – Broad spectrum fungicidal properties. Mix per label rate and apply every 7-14 days.
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Bacillus subtilis – This beneficial bacteria has antifungal action. Apply weekly as a preventive.
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Potassium bicarbonate – Fungistatic properties disrupt spore germination. Spray plants every 7-10 days.
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Hydrogen peroxide – Oxidizing properties can kill fungal spores on contact. Use 3% solution mixed with water and apply liberally to affected leaves.
Always cover foliage thoroughly when spraying. Monitor carefully for any phytotoxic effects like leaf burn.
Turning to Chemical Fungicides
For more severe infestations, specific chemical fungicides will provide stronger efficacy:
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Mancozeb, chlorothalonil, myclobutanil, trifloxystrobin – Available under various brand names. Rotate between chemical classes to avoid resistance.
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Copper products – Broad spectrum fungicidal action but can cause phytotoxicity if over-applied. Do not exceed label rates.
When using any chemical fungicide, proper protective equipment, technique, timing, and adherence to the label directions are critical to avoid plant injury or lack of control. Combining cultural practices, sanitation methods, and judicious fungicide use provides the best disease management program.
Tolerating Some Defoliation
The good news about Anthracnose on hollies is that despite the dramatic yellowing and leaf drop, it rarely kills affected plants on its own. Holly bushes can tolerate some defoliation without long term harm. As long as proper cultural care and fungicide treatments are implemented, the plants will generate new growth. However, repeatedly losing leaves year after year will impact plant vigor and aesthetics. So taking prompt action at the first sign of infection is key.
Removing Affected Foliage
To reduce the spread of spores, prune out and destroy any leaves showing early spotting before they turn yellow. Rake up and dispose of fallen leaves as well – do not compost them. Sterilize pruners between cuts with isopropyl alcohol to avoid transmitting spores on tools. Removing infected foliage helps limit reinfection the following season. Fungal fruiting bodies can overwinter on leaf litter under the bushes.
Monitoring Environment and Plant Health
Be vigilant with your monitoring and adjust care practices as needed to promote growth and minimize stress. Ensure adequate moisture, nutrition, light levels, and spacing for air movement. The healthier your holly bushes are, the better they’ll be able to resist and recover from Anthracnose damage. While fungal diseases can be frustrating, keeping up with prevention techniques, early treatment, and proper sanitation will help you stay on top of Anthracnose.
Holly Disease Leaf Spot Causes
There are several fungi that can cause Holly leaf spot. These are Phacidium curtisii, Coniothyrium ilicinum, or Phytophthora ilicis. Even though the fungi attack different kinds of holly plants, the problems they cause are very much the same.
Holly Leaf Spot Symptoms
The symptoms of this holly disease are easy to see. Most types of holly plants will first show black, yellow, or brownish spots on the leaves. Eventually, the leaves will start to fall off the bush. Most of the time, the holly leaves will fall off the bottom of the plant first and then move up. Most plants lose their leaves in the spring, but the spots will show up first in late fall or winter.
My Holly Has Yellow Leaves With Black Spots
Why are my holly leaves turning black?
It sounds like your holly plants have been infected with a fungal disease known as holly leaf spot, sometimes called holly tar spot. It can be caused by several different fungi, but the symptoms are similar: the leaves develop black, brown, or yellow spots. Eventually, the infected leaves fall off the plant, leaving your holly bare and spindly.
Do Hollies have yellow spots?
Yellow spots appear on the leaves of American and English hollies in May. These turn reddish-brown and finally black by fall. In years of heavy rainfall, berries, as well as leaves, are spotted. Prevention & Treatment: Remove and destroy badly spotted leaves, prune to improve air circulation and overcrowding, and clean up and destroy fallen leaves.
How do you know if a Holly plant is dying?
The symptoms of this holly disease are easy to see. Most types of holly plants will first show black, yellow, or brownish spots on the leaves. Eventually, the leaves will start to fall off the bush. Typically, the holly leaves will start to fall off the bottom of the plant and work its way up the plant.
What is holly leaf spot?
One of those problems is holly leaf spot, also known as holly tar spot. This holly disease can defoliate a holly bush, so it is important to keep a close eye out for it. The symptoms of this holly disease are easy to see. Most types of holly plants will first show black, yellow, or brownish spots on the leaves.
