Winter Injury Observed in Ornamental Plantings

Extension educators and staff across the state have received reports about various species of evergreens with brown tips, dieback, and possible fungal infection. Already in 2025, plants reported with winter injury symptoms include arborvitae, cypress, holly, rhododendron, boxwood, pachysandra, and mahonia (Images 1 and 2).

For many of these plantings, the problem may have started last summer and fall when much of Pennsylvania was in a drought. Trees and shrubs that have been planted in the last 1-3 years are more susceptible to drought than established trees and shrubs. Further, drought-stressed plants are more susceptible to winter injury and other stressors such as fungal infection and increased insect pressure. Compounding the drought conditions from the last couple of summers and the recent cold winter, evergreen plants are susceptible to desiccation which causes browning and death of plant tissue. Leaves and needles lose water during the winter especially if they are in locations with a lot of wind or sun. The plants can't replace the water when the ground is frozen during the winter, so the leaves or needles dry out and turn brown. Broadleaf evergreens such as rhododendron can have curled up leaves or marginal leaf browning.

Reducing stress on plants is one of the best management options. Planting in protected areas and watering during extended dry periods can help reduce stress. Deep waterings are better than frequent, shallow waterings. For plants younger than 5 years, consider watering into late fall – before the ground has frozen – so the plants have adequate water going into the winter. A 3-4" layer of mulch helps to conserve moisture and insulate the ground. 

In cases of windbreak plantings, be sure to use species that are suited for high-wind areas. Some hybrid evergreens, such as Leyland cypress, are shallow-rooted and fast-growing and do not have the longevity that other species offer.

If plant tips or limbs are brown, they will not recover. Check to see if branches are still alive by scraping away a small area of bark to look for healthy green tissue. Dead plants should be removed. Prune and remove completely dead branches on woody plants showing dieback. Pruning helps stimulate new growth, reduces areas for fungi to take hold, and removes inoculum if there is already an infection present. The evergreen groundcover, pachysandra, is more susceptible to the disease Volutella blight when plants are stressed due to drought and winter injury. Thinning beds to improve air circulation will reduce disease.

Fungicides can be used, but they will only protect new growth. Examples of fungicide active ingredients include copper, chlorothalonil, and mancozeb. Read the label and apply according to the instructions.