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Tree Maintenance

TREE CARE ALERTS

Spruce Trees - White Pine Weevil

White pine weevil have been damaging spruce tress within the RM of Edenwold (2019). The damage is characterized by the top main shoot turning brown which prevents further new growth from devloping. To combat the spread of the weevil, the tree must be pruned of the dead parts as soon as the damage is noticed. Infected branches can be disposed of at the City of Regina Landfill.

 

Black Knot Infestation

Cherry, Chokecherry, Plum, and Prune Trees are prone to this fungus.

Black Knott fungus is characterized by lumps (galls) that feed on the tree. Initially the galls may have a cork like appearance in the early stages and, over time may progress from a spongy green mass to the hardened "charcoal like" mass. If left untreated, the tree will become stressed, distorted and ultimately die. This fungus can be spread by wind and rain but can be controlled by cutting and burning the affected branches. Best results will be achieved if pruning is done in late winter/early spring, prior to the release of spores in the spring. Infected branches can be disposed of at the City of Regina landfill.  Visit this link for more information: White City Garden Club - Resources Page

 

Rhizosphaera needlecast

Rhizosphaera kalkhoffii

Hosts

Spruce

Distribution and Disease Cycle

Description of this image follows
Colorado spruce infected with Rhizosphaera kalkhoffii.
Photo credit: Joe Zeleznik and Kasia Kinzer, North Dakota State University

Rhizosphaera needlecast is a fungal disease affecting mainly Colorado spruce, and occasionally other spruce. The disease begins in the lower portion of the tree with infected needles being shed, causing branches to look sparse. Spore dispersal from infected needles occurs during wet weather in spring, spreading by rain from needles infected the previous season to newly emerging needles. Under suitable conditions, the disease gradually progresses up the tree continuing to cause loss of needles, leading to eventual decline of trees.

Symptoms and Signs

Description of this image follows
Close up of infected needles (top) and healthy needle (bottom).
Photo credit: Michael Kangas, NDSU - North Dakota Forest Service, Bugwood.org

Symptoms of Rhizosphaera needlecast appear in the spring following infection, with infected inner (2nd year) needles turning yellow, then purplish-brown by end of summer, with black fruiting bodies appearing in lines as they emerge from needles' stomatal pores. Most infected needles will be shed by fall, although some may remain attached, acting as an infection source the following spring. Repeated infections will cause trees to begin having a sparse looking interior and after 3-4 years of severe infection, branches may begin to die.

Control

Management of Rhizosphaera needlecast can be difficult. To reduce the spread of Rhizosphaera needlecast, avoid pruning or shearing trees during wet weather and sterilize pruning tools frequently by dipping in 70% alcohol for 3 minutes. Remove any severely infected branches and rake fallen needles from the base of trees where practical. Promote good air circulation and encourage rapid drying of foliage by mowing weeds or other vegetation near trees. Chemical controls registered for Rhizosphaera needlecast control include fungicides containing chlorothalonil. Apply as per label instructions beginning in spring when new shoot growth is 1 to 5 centimetres in length, and again several times at 3-4 week intervals until conditions no longer favour disease development.