Brown Leaves in Summer? Vaughan Trees

Trees are supposed to change colour in October, not July. When leaves brown out mid-summer, the cause is usually water, heat or a leaf fungus. Once in a while it is the first sign of something deeper. The pattern on the tree tells you which.

Common Causes

Five causes explain most brown leaves in a Vaughan summer.

Drought and Leaf Scorch

After a hot, dry stretch, leaves lose water faster than the roots can replace it. The edges and tips go brown and crispy first, and the browning shows up on the sunny, windy side of the tree. Young trees, trees beside driveways and trees in narrow strips of lawn get it worst, because their roots have the least soil to draw from.

Tar Spot on Norway Maple

If your maple leaves have raised black spots that look like drops of tar, that is tar spot. It is a fungus, and it is cosmetic. The tree may drop leaves a bit early, but it comes back fine next spring.

Anthracnose

After a cool, wet spring, a leaf fungus called anthracnose causes brown blotches along the veins of maple, ash, oak and sycamore leaves. Some leaves drop in early summer, and the tree often puts out new leaves later. Like tar spot, it rarely does lasting harm.

Root Damage

New driveways, patios, pools, additions and even regrading can cut or smother roots. The tree may look fine the first year, then brown out in the second or third summer as the damage catches up. Browning on the side where the work happened is the clue.

Girdling Roots and Wilt

Some trees, Norway maples in particular, grow roots that wrap around the base and choke the trunk over time. Look for a trunk that goes straight into the ground with no flare. A wilt disease in the wood can also cause sudden browning on one limb or one side. Both need a closer look.

How Worried Should You Be?

• Brown edges all over after dry weather: water and watch. Usually fine.
• Black spots on maple: cosmetic. Rake the leaves in fall.
• One side or one limb browning: get it checked.
• Same branches thin and late every spring: dieback is setting in.
• Dead branches over the house or driveway: act before they fall.

What to Do Now

• In a dry spell, give the tree a slow, deep soak once a week. Lay a hose at the edge of the canopy, where the feeder roots are, and let it run.
• Put a ring of mulch about 5 to 8 cm deep around the base, kept a hand’s width off the trunk.
• Rake and bag tar spot or anthracnose leaves in the fall.
• Don’t fertilize a drought-stressed tree. It pushes new growth the tree can’t support.
• Scratch a twig with your thumbnail in fall. Green under the bark means it is alive.

Vaughan Conditions

Vaughan’s clay soil swings between waterlogged in spring and baked hard in August. Roots stay shallow in clay, so trees feel a dry summer fast. We see the most scorch on young boulevard trees and on trees squeezed between driveways in Vellore Village and Sonoma Heights. Tar spot shows up on Norway maples all over older Woodbridge and Thornhill streets almost every year.

If the tree is on the boulevard between the sidewalk and road, it belongs to the City. Call Vaughan Public Works at 905-832-8585 rather than touching it.

Trees That Brown Out Most

• Norway maple: tar spot, scorch and girdling roots. The most common summer browning call we get.
• Silver maple: scorch in dry years, with leaves curling and browning at the edges.
• Birch: shallow roots and a love of cool, moist soil make it suffer first in a hot summer. Browning at the top can mean borers.
• Honey locust: drops small leaflets early in drought, which looks alarming but usually isn’t.
• Linden: leaf scorch on street and driveway trees after a heat wave.

Check Again in Spring

Summer browning tells you the tree had a hard season. Spring tells you whether it got through. In May, walk around the tree and look for branches that never leaf out, or leaf out late with small, pale leaves. One or two dead branches can come out with a normal trim. A crown that is a third or more dead is a different conversation.

When to Call Us

Call or text (289) 444-0864 if browning sticks to one side, if branches stay bare the following spring, or if dead limbs hang over something that matters. We come out the same day and tell you straight whether it is weather or a real problem.

When dead branches start showing, taking them out early keeps them off your roof and helps the tree put its energy into healthy wood. Our tree trimming and pruning page covers how we do it. To check whether a tree has passed the point of saving, see how to tell if a tree is dead.