Summer is here! It’s a great time to get outside and enjoy your trees. However, this season can also be tough. Storms, droughts, and pests, can put a lot of stress on your trees, so it’s important to keep a close eye on them and look out for signs of trouble.

Pests & Disease

Keep an eye out for those pesky defoliating caterpillars! Unfortunately, control of these critters often requires proactive care, early in the season. However, even if the caterpillars have already gotten to your foliage, you can help ease the stress on your tree with some ArborGain™. The boost to the soil will give your tree the nutrients it needs to recover.

This is also the time of year to make sure your trees are up to date on their vaccinations. When was the last time your Ash tree got injected? Or your elm?

Ash trees are on a 2-year treatment cycle to protect against Emerald Ash Borer, and Elms should be injected every 3 years to guard against Dutch Elm Disease.


Our summers are getting hotter and drier. This takes a major toll on our trees as access to enough water is essential to their survival.

If you don’t have an irrigation system, you will need to make sure you’re watering your trees regularly. And it should be noted, most irrigation systems do not provide sufficient water to mature trees.

For younger trees especially, deep watering should be conducted two to three times per week during drought conditions. We suggest a hose on a slow dribble for 30 to 40 minutes.

  • Move the end of the hose three times during this process to soak all sides of the root zone, about 12”-18” from the tree trunk.
  • A soaker hose run for the same amount of time solves the issue of having to move the hose end around. Avoid spraying the foliage with water during the day as this can contribute to the leaves drying out and looking shrivelled.
  • You can also direct downspouts toward the root zone of your trees to utilize rainwater.
Don’t forget about mulch!

Mulch helps keep moisture in the soil. But please be careful not to over do it! You want to think donut, not volcano when it comes to mulch. Keep the area at the base of the trunk clear and form a ring of mulch starting about 3” from the base.

Give your soils a boost. 

Ask your arborist for an ArborGain™ treatment. Aside from containing humates, active bacteria and other organic materials that will improve your soil, ArborGain™ contains yucca. Yucca are desert plants that can handle harsh environmental conditions, like drought. In ArborGain™, they pass their survival skills on to your plants, and help make them more drought-resistant!

Another soil superhero is Biochar! Biochar is a carbonized biomass. When added to soil it acts as a sponge and increases water-holding capacity. This will help sustain trees through periods of drought.


There’s nothing quite like a good old fashioned summer thunderstorm! However, when the wind picks up and the rain comes down, you want to make sure your tree is fit to weather the storm.

Here are some signs that your tree is vulnerable to storm damage:

  • Unbalanced canopy
  • Large, overextended limbs
  • Weak unions
  • Cracked limbs
  • Cavities or decay
  • Restricted root flare
  • Limited growing space for roots

If you spot any of these signs in your tree, have your arborist come by for an inspection. They can help make your tree storm resistant through structure pruning (weight reduction and balance), or even installing steel cables or bracing bolts to support weak unions and repair cracked trunks.

Summer is the best time to enjoy the outdoors, and your trees. By being proactive with your tree care, you can make sure they’re there for you to enjoy for years to come!


Be Good to Your Trees!

Kristie Nairn, MA, MMst
Cohen & Master Tree and Shrub Services Ltd.