Here are some tips from the 2011 ISA Award Winning Arborist Mike Gavin.

Mike created the “Tree Report Card”, which you can find on Casey Trees website, the Tree Report Card looks at the tree canopy in Washington, D.C., showing how many trees there are and where they are located. It grades the city in five key areas: awareness, coverage, health, planting, and protection. Unfortunately, last year’s Tree Report Card was the worst yet, dropping from a “B” in 2009 to a “C” in 2010.

How does Washington, DC ‘s tree canopy compare to other U.S. Cities?

Washington, DC’s tree canopy covers 35% of the land area of the District. As the District is a “flat” city (buildings cannot be more than about 12 stories tall – no skyscrapers – so big buildings go out rather than up) and as DC has been “built-out” for over a century, the city has done a great job with canopy cover. However, more needs to be done to minimize the need for expensive engineered stormwater management systems. So the goal is to reach 40% canopy cover by 2035.

New York has 24% canopy cover, Baltimore has 27%, Philly has 20%. So DC is doing well among large east coast cities.

Do you believe in global warming?

I have been fortunate to work closely with members of the scientific community and personally believe that climate change effects are occurring due to emissions and land cover changes (built surfaces). These changes don’t always make it hotter or drier everywhere – it’s not always about warming. They change patterns of temperature and precipitation. They can also make rain events more severe over shorter periods of time.

What is the best time to prune?

The best time to prune is when trees are actively growing. That way, they can compartmentalize the wounds better. There are certain pests that are active at certain times of the year, so it can vary somewhat depending on the type of tree and what pests that tree gets in your area. It is best to consult with an Extension Agent or Certified Arborist if you are not sure.

How can I prevent my poplars from splitting?

Not sure how to answer this one! Would be happy to be more helpful but would need additional information.

How deep should I plant a sapling that’s about 4 feet high and has buds?

Always look for the root flare – that’s the place where the trunk starts to become the root system and widens out, like the flare on a pair of flair-legged pants. That flare should not be buried but should sit at or slightly higher than finish grade.

– How can I keep my fruit trees (Apple, Peach, Pear) healthy, (I keep seeing DC region fruit trees with fungus, and disease)?

This is tough. Apples, peaches, and pears are all members of the Rose family. This family has many of our most attractive and important fruit-bearing trees. It is also one of the most pest-prone plant families.

You will follow different regimens depending on whether you are maintaining these trees for crop (food) or ornamental purposes.

Again, I recommend that you consult with a Cooperative Extension agent (crop or ornamental) or Certified Arborist (ornamental) for the best recommendations or professional management of your trees.

Director, Consulting Group at SavATree ( SavATree is a tree care company with offices in seven states and the District of Columbia.