Does Hurricane Stress Affect Your Landscape

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Hurricanes Florence and Michael resulted in significant damage to North Carolina Agriculture at all levels. Total losses have exceeded $1.1 billion in crop losses to Florence and the damages from Michael are still being calculated. There will also be significant losses in landscapes around the state. The roots of plants require oxygen. Continuous rain can result in saturated soils and oxygen deprived root zones. Severely stressed trees have varying responses that are difficult to predict. Sometimes they grow fine in the following season and then begin to decline and die more than a year after the stress. Other times, the stress response can manifest quickly.

Dr. Barbara Fair, NC State University Landscaping Specialist, has received numerous reports from around the state regarding Callery pear, cherry and other typically spring flowering trees and shrubs blooming and leafing out again right now.

Dr. Fair explains, “Late winter and spring flowering trees and shrubs begin to develop new flower buds for the following year after they finish flowering and during the summer when they are in full leaf. There is a complex relationship between flowering response, plant hormones and plant chemistry. Day length and temperature play an important role in when plants flower in general, and when seasons change plants respond by altering their internal chemistry and hormone levels. This is normal, but when storms come through and change the conditions directly around the plant, it can trigger an unusual response such as plants blooming out of season. The storm can lead to stress which leads to a change in the plants hormone levels and chemistry. Thus, plants bloom at strange times and may even produce leaves where others were lost.

“It is rather complicated and no one factor seems to explain it. As with most issues with plants, it is usually a suite of factors that play into a plant’s response to stress.

“You should also note that it is unlikely the trees will bloom again in the spring. They may have a few blossoms left over after this flush, but blooming will be much diminished, if at all. There should be no problem when it comes to developing new leaf buds and leafing out in the spring/early summer, but they are using some of those preformed leaf buds as well now, and so you might see some re-growth, late leaf flushing, or reduced leaves at the beginning of the season. If the trees are otherwise healthy, there should be no long-term effect to the production of new leaves. Callery pears are one of the toughest plants in the landscape and should be fine despite the hurricane’s effects.”