Hollies (Ilex spp.) Are best known for their glossy foliage and bright red berries. Several forms of holly are evergreen, providing winter colour to the garden in hedges or topiaries, and are often used for holiday decorations. While hollies are usually extremely hardy, thriving in U.S. Department of Agriculture plant hardiness zones 3 through 9, these shrubs are occasionally susceptible to weather damage or fungal infection, which can cause the leaves to turn brown.
Weather Damage
Big brown splotches on the leaves, particularly around the edges, may be a sign that your holly plant contains ongoing weather damage, such as a sudden cold snap or even a prolonged dry period. If rain drops below 1 inch per week, water your holly to ensure the roots are getting enough moisture. Hollies are bouncy and will usually recover quickly from weather-related shocks.
Fungal Infections
Smaller brown or yellow spots in the leaves might indicate that your holly plant has soared to tar spot or another fungal disease. Fungal diseases are most likely to strike from the moist spring season, though they might appear at any given time of year. If left untreated, the spots will probably spread and darken until they turn black. Infected leaves may drop from the trees.
Treatment
Leaf spots aren’t normally a severe threat to the holly plant as a whole. Appropriate care of the plant may often cause the disease to naturally disappear and decrease. But if you have a severe illness, where leaf patches influence a large portion of the holly’s leaves, you may use a broad-spectrum fungicide like maneb or ferbam. Spray to the point of runoff once a week till leaf spots are reduced. Always follow instructions carefully when using chemical fungicides, and be certain to keep dangerous substances out of reach of children and pets.
Prevention
Great care can generally prevent holly diseases from happening. Make sure that your soil has good drainage and that your holly plant receives a lot of sunlight. Add a layer of compost into the soil each spring to strengthen nutrient levels, and mulch around the base of the holly to help keep down weeds and retain moisture. When watering, prevent splashing the leaves, as prolonged dampness can encourage fungal infections. If leaf patches do seem, prune away contaminated divisions as soon as possible to limit the spread of the disease.