Yew trees, conifers that herald the winters to come

In the spring of 2026, a number of yew trees in the Jardin botanique’s collection were found to be in poor condition. Weather conditions particular to the winter of 2026 were the likely cause.

Spring 2026 took its time getting here. April and May were especially cool and damp, which delayed the flowering of many species of trees, shrubs and herbaceous plants. In addition to the long wait before we got to see nature emerging from its winter slumbers came the surprise discovery of the state of several of our conifers at the Jardin botanique, with their branches looking all scorched and withered. The most severely affected plants included a number of yews (Taxus spp.), in some cases on all their above-ground parts (Photo 1).

A plant-health issue was initially suspected, and portions of branches and roots were collected and analyzed using molecular approaches. But the results revealed no sign of pathogenic organisms in the samples examined, either bacterial or fungal.

Winter burn

The observations made at the Jardin botanique were also reported in many yew trees in the Montréal area (Photo 2), suggesting that the phenomenon is not limited to a particular site, but is widespread throughout the region.

Which led us to consider that the particular climate conditions of winter 2026 may have been responsible for the situation. As it happens, yew trees, like several evergreen shrub species, are sensitive to winter burn. This comes about especially in late winter, when daily temperatures occasionally rise above 0 °C. Plants become photosynthetically active again and they transpire, leading to water loss through the stomata of the leaves or needles. But when the soil remains frozen, roots can’t compensate for the loss of water, which brings about a physiological imbalance that in turn leads to tissue damage and browning of the foliage.^1,2 Important fluctuations in temperature along with strong winds may exacerbate that imbalance and amplify its effects on foliage.

A winter marked by contrasts

Curiosity led me to examine more carefully the meteorological data of the last weeks of winter 2026. Two episodes marked by especially abrupt temperature fluctuations took place late in the season in Montréal:

• On February 28, a temperature of 7.2 °C was recorded, before the mercury plunged to -16 °C during the following night.
• On March 16, a foretaste of spring seemed to be settling in, with the temperature reaching 13.8 °C. Nevertheless, there again, conditions were quick to change, with wind gusts reaching 90 km/h and a nighttime temperature plummet to -11 °C.

Such contrasting conditions are stressful for plants that are sensitive to this time of year.

Of course, it’s difficult to say with certainty that these events are the direct cause of the winter burn observed this spring on a number of our yew trees. Still, there’s not much doubt that this type of temperature fluctuation, in combination with forceful gusts of wind, creates a set of conditions that are especially conducive to the occurrence of the sort of winter damage and burn that we observed in the spring of 2026.

The situation is all the more worrisome in that climate change is more than likely to increase the frequency of this sort of event over the decades ahead. Yew trees are among the first conifers to suffer the effects of extreme weather conditions. If I were a yew, I’d be worried.

References

¹Ophardt M. and Hummel R. L. (2016). Environmental injury: Winter burn of evergreens. Washington State University Extension. 5 pp.

²Marquesen S. (2025). Preventing Winter Burn on Evergreen Landscape Plants. PennState University Extension. 6 pp.