Problem type: Environmental
Name of problem: Winter Browning
Plant name(s): Pine, spruce, fir, juniper, cedar
Symptoms / Characteristics:
Needles turn light tan or reddish brown in color. Discoloration usually begins at the tips of the needle and moves down. Cedars may look pale and bleached.
Winter browning occurs due to foliage losing water faster than it can absorb. Warm, sunny, windy periods increase water loss. Frozen soil or soil low in moisture prevent roots from taking up water.
Needle death is usually more prominent on the side of the tree facing prevailing winds or sunny south exposure. Sun reflection from building surfaces such as brick, concrete and light colored metal siding increase winter injury. Other causes include white or lava rock around the base of the tree, poorly developed root systems (improper planting) and stresses from insects and diseases. Needles may dry out and die in the previous fall or early winter but will hold their green color until warmer temperatures arrive in the spring, delaying the onset of browning symptoms.
Plants exposed to the most sunlight (south-southwest exposure) and fluctuations in temperature during the winter months are more prone to injury. Plants that have suffered drought stress at any time during the year will not be able to withstand dry winter conditions as well as those that have been adequately watered. Branches exposed above the snow line can be more severely injured due to reflection. Above average temperatures and warm dry winds cause plants to break dormancy. When cool conditions follow, the cold then kills plant parts. Winter browning can also be associated with low temperature kill.
Control / Preventions:
Total prevention is difficult. Plant susceptible species in sheltered locations. Water plants properly throughout the summer, reduce watering going into fall to harden off and give a heavy application of water just before freeze up. Snow fences can be used to collect snow for cover or burlap covers can provide cover and shade. Anti-desiccant sprays can be applied to reduce water loss in the plant. Mulches can be placed around the base of the plant to retain moisture. Avoid nitrogen applications in the fall to avoid any new succulent growth before winter. Periodic watering of trees or shrubs if the ground isn't frozen can be very beneficial. In spring when plants are looking brown, do not take immediate action by pruning or removing the plants. Supply water and give the plant a chance to recover and send out new growth. Wait until late spring to ensure all new growth has emerged before pruning. Any remaining dead branches can then be removed to ¼" above live buds. Removing dead branches is beneficial in that it eliminates an entryway for insects and diseases. Water plants well as soon as the ground thaws in the spring. A light fertilizer application will help stimulate new growth, but apply only after signs of new growth has begun. Injured plants will be slow to initiate new growth.