Arborists have long attempted to portray how trees live as a reflection of how humans live. Trees, like humans, need sustenance, care and a healthy diet or else they can become sick from an onslaught of potentially life threatening bacterial and viral diseases that can be airborne or vectored (wind, birds, insects and tools).

People should know their trees and what type of diseases can infect them.

Let me share a not too uncommon story about how a once healthy tree comes down with a severe case of a bacterial infection.

Good Intentions

Over the spring weekend, Mac noticed that his Bradford pear had branches that were hanging close to his roof line, causing concern for both him and his insurance company. He decided that when his landscaping company came Monday to mow the lawn and hedge his shrubs, he’d ask them to trim the pear back from the roof line.

Monday arrived and the landscapers showed up, unloading their equipment for the weekly service. Mac approached Bobby, the foreman, with the request and received a “no problem” in response.

rusty hedge clippersIn a short time an extension ladder, rusty power hedgers, worn pole pruner and a pair of dull loppers appeared. After a few cuts the roof was cleared. Satisfied, Mac gave the crew an extra $40.00 for the work.

Problem solved, thought Mac.

Or was it ..

Spring turned into summer, summer into fall. With Halloween approaching, Mac started planning out his annual scary outdoors display. Included was a feature where a ghost flys down from his chimney to the same pear tree trimmed by his landscapers in spring. With a cable in hand, Mac climbed his A-frame ladder to attach it to the tree when he noticed what appeared to be burned branch segments on the pruned side of the tree. The closer he looked, the more they looked like they had been scorched with a blow torch.

Shrugging his shoulders, Mac didn’t give it a second thought. After he attached the cable and climbed off the ladder, he looked at the rest of the tree but didn’t see any other foliage with similar appearance anywhere else. But as he glanced over to the pyrcantha hedge that wrapped around the front of his house, he also noticed a similar burnt appearance on the ends of branches. Now he was perplexed.

Transmission of a Disease

fireblightSo what happened?

When Mac’s landscapers came to his house that spring day, they had just trimmed pyracantha and crab apple at another property that were infected with a bacterium called Fireblight.

The bacteria remained onto their pruning tools. When those same tools touched Mac’s tree and shrubs, they became infected.

Stories like this happen every single day.

How to Reduce Risks

So how can we avoid cases like this?

First, we need to pay attention to the species of trees and shrubs we have, along with knowing what diseases they can contract. In today’s age of the Internet, looking up that info is relatively easy.

Second, if you hire someone to maintain your trees and shrubs, make sure they know diseases and enter your property with sterilized tools. You’d be aghast if you knew how many so called ‘professionals’ don’t know the first thing about diseases.

We understand it’s impossible to protect your property from diseases that are vectored in by the wind, birds or insects. However, if you or your professional do the following things you can reduce the risk of infecting your trees and shrubs*:

  • if it’s a virus or viroid, disinfect your tools
  • if it’s a vascular fungus or bacteria, and/or forms oozing cankers, disinfect your tools
  • avoid cutting active, oozing cankers; wait until they dry
  • if you are pruning irreplaceable plants, disinfect your tools
  • choose a disinfectant treatment that has been shown to be effective through published research

You’d no sooner let a medical professional treat your or your family with an unsterilized tool – why treat your trees and property any different?

* source: Dr. Linda Chalker-Scott, “Sterilized Pruning Tools: Nuisance or Necessity?