Maples and other trees can be damaged by drought stress in dry summer weather
Southern Ontario frequently experiences hot, dry conditions during the summer months. When drought conditions are prolonged, these dry conditions can have a negative impact on our rural landscape. Deep rooted species like oaks have a higher tolerance of drought than more shallow-rooted species like sugar maple, that can suffer temporary or permanent damage.
Drought periods that occur during the long-day months of June and July are more damaging than those in August and September because of increased day length. Dry summer breezes also contribute significantly to drought stress.
SIGNS OF DROUGHT STRESS
- under-sized leaves; limited shoot growth
- Tree leaves wilt, usually starting from the top of the tree, then downward
- Tissue in the leaf margins dies, turning brown
- Upward curling or rolling of leaves
- Some species show out-of-season ‘fall-like’ colour change
- Leaf browning (scorch) is a sign that drought damage has already occurred.
- Entire leaves turn brown and fall from the tree
It is important to apply enough water to thoroughly wet the root-zone to a depth of 25-30 cm
- Install a mulch around the base of the trees, if none is present
- Water the trees slowly and deeply at least weekly; supplement as drought conditions lengthen
- Increase the frequency of watering when first signs of stress are observed
- Water in the early morning, if possible to reduce water loss to evaporation
- Consider the use of tree-watering bags to conserve water and time investment
Trees planted in the past 2-3 years, especially those planted on exposed sites, are more sensitive to drought than older trees. Their roots often struggle to replenish the moisture lost through transpiration from the leaves.
Planting Container-Grown Native Maples
Maple Leaver Forever (2017), www.mapleleavesforever.com Toronto
Watering Tips for Drought Conditions [PDF]
University of Maryland, 1000 Hilltop Cir, Baltimore, MD, 21250, Extension, HG 85, rev 2010