English Boxwood - Knowledgebase Question

Williamsburg, Vi
Question by kksbadger
March 11, 2010
Our 20-year-old boxwoods are turning yellow. Help!


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Answer from NGA
March 11, 2010

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Without being able to inspect the plant, I can't positively diagnose the problem, but it sounds suspiciously like winter damage. Winter damage occurs on boxwoods (Buxus sp.) when unseasonably warm winter days are followed by freezing temperatures. During the warm period, the plant begins to come out of dormancy and the cambium or conductive tissue begins to fill with additional water. When the temperature drops below freezing, the water freezes. The expanding ice splits the tissue resulting in death of the affected tissue. Cold, dry winds pull moisture from the affected branch resulting in a freeze-dried, "freezer burn" effect. Depending upon conditions, whole plants, just sections of a plant, or only the tips of branches may be affected. Tip burn is quite minor and only affects the tips of branches. Simply remove the dead tips with pruning shears or hand pruners. The plant will recover. Sectional winter burn or die-out occurs when one or more whole branches die. The most recognizable sign is when the leaves turn pale yellow to almost white. On close inspection, bark splitting from the branches will be evident. Splitting can continue all the way to the base of the branch. Prune these branches back to the point where the splitting stops. Full recovery can take several years. Winter burn of the total plant is the most devastating. In this case the whole shrub will turn a pale yellow and every branch will have splitting bark. For these plants, the only chance for recovery is to severely prune the plant. In spring after all chances of severe frost are past cut all branches back. This method is not always successful; be prepared to completely remove the plant if it does not recover. Hope this coming winter is less severe!

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