Important garden tasks

Pruning and disposing garden and tree waste is an important gardening task at this time of year.

Pruning and disposing garden and tree waste is an important gardening task at this time of year.

It’s important, says City of Red Deer urban forester Elaine Johnson, that people protect their trees from bronze leaf disease.

The disease attacks several species of poplars and hybrids, including two highly susceptible varieties common to Red Deer — Swedish columnar aspen and tower polar.

The disease can also impact the native trembling aspen, which grows in parks and natural areas around the city, Johnson said.

Diseased leaves turn dark reddish-brown, chocolate brown or bronze with the discolouration beginning at the edges and progressing to the base.

All of the leaves on a shoot may show signs of the disease. Discoloured leaves often show up first on the lower branches of the tree but they may be scattered throughout the crown of the tree or isolated on a few branches.

Infected leaves remain on the tree throughout the winter.

Johnson says gardeners can prune diseased branches between 20 cm to 30 cm (eight to 12 inches) below the visible sign of infection. All pruned material and fallen leaves should be disposed of in the city landfill.

The material should not be composted, chipped or used as firewood, she said.

Trees should be monitored closely in the spring to determine if they are distressed or infected, Johnson said.

— copyright Red Deer Advocate