Learn About Tree Pest and Disease Management
The key to protecting your trees against the damaging effects of diseases is determining the issues source. With our tree care solution, you can count on our certified arborists to diagnose the problems affecting your tree. Here are some common tree diseases, pests, and insects:
Gypsy Moths
These pests, which are most destructive in their larval stage or as caterpillars, strip away foliage from a wide variety of trees. Repeated defoliation stresses trees and can lead to mortality, especially in urban or drought-stricken areas. In addition, gypsy moths can weaken tree regeneration due to impacted seed production and soot sprouting.
Signs and symptoms of a gypsy moth include:
- Egg masses on tree trunks and outdoor objects
- Holes in leaves
- Defoliation of trees
Defoliation will result in the dieback of twigs and branches. It will also make affected trees vulnerable to disease and other pests as they spend their energy reserves to regrow leaves in mid-summer.
Hemlock Loopers
The damage caused by hemlock loopers is visible on conifers during epidemics in late July and early August. The trees turn a reddish color, which is very characteristic of hemlock looper outbreaks. Feeding larvae damage the needles, causing them to dry, turn red, and drop in the fall.
Hemlock looper outbreaks develop and subside very suddenly. Additionally, the wasteful feeding of this species and its rapid population growth make it a serious defoliator.
There are 4 to 5 larval stages, depending on the region of Canada. When mature, larvae look for a pupation site. During heavy infestations, trees are covered with silk strands produced by larvae as they descend the tree trunks in search of food or pupation sites.
The insect has only one generation a year and overwinters in the adult stage.
Aphids
These small, soft-bodied insects feed by sucking the nutrient-rich liquids from plants. Some feed on only one type of plant, while others colonize various plant groups. Although aphids can vary widely in color, their common names include greenfly and blackly.
Tar Spots
Tar spots, caused by a fungal pathogen Rhytisma acerinum, are a common condition of the leaves of maple trees. They start as small yellow spots on growing leaves and expand into large black botches as the summer weather progresses. The treatment for this condition is a deep root fertilizer as well as disposal of the leaves.
Diplodia Tip Blight
The disease is primarily seen on Austrian, Red and Scotts Pine however sometimes attacks other conifers like spruce and fir.
Fungicide applications help reduce infections in new shoots. New growth must be protected from bud swell to full expansion of the candle. It is important that the first application if administered on the tree prior to bud break and before candles emerge out of the sheath. Two or Three applications may be needed. Shoot removal helps the tree look better and will increase its vitality. Trees should be kept in good health with regular maintenance, watering during droughts and a routine fertilizer shedule.
Trees with heavy levels of disease are best removed from the site
Eastern Tent Caterpillar
The adult stage is a reddish- brown moth that deposits eggs in the summer. During winter, egg masses encircle smaller twigs of the host tree. The egg mass looks as if it has been varnished, can be up to 3/4 inch long and contains 150-350 eggs. When the eggs hatch the following spring, the caterpillars feed voraciously, causing damage and sometimes defolating the host tree. The fully grown caterpillar is black with white stripe down the back with several bright blue spots along each side.
The management is to remove the egg masses in winter to reduce damage to the trees. Remove larvae by clipping and destroying the tents while they are still small and inside the tents. A commerical grade bacterium or chemical application may be used to conrol the caterpillar.
Tree Borers
Borers feed unseen inside the roots, trunks, branches and twigs of many trees. Depending on the species they girdle the vascular system and disrupt the normal flow of water and nutrients or weaken the wood to the point where the structure of the tree is compromised.
The first signs of a borer attack are often sawdust like material and or sap/ resin oozing from small holes in the tree. Bark may develop cracks that eventually cause areas to break off. Leaves in the upper part of the tree are undersized and discoloured. Branches begin to die back and decay.
Bronze Birch Borer
Applications in early spring can reduce further borer infestations however do not expect ot control larvae that are already inside the tree. Best to remove heavy infected trees.
When considering planting a birch tree select well drained, sandy soils. Birch sruggle in clay soils. Keep trees healthy by proper fertilizing, watering, mulching and managing other insects/ diseases. Fertilizing can increase a birch trees tolerance to borer attack and help it over come previous damage.
Hemlock Wooly Adelgid
These are aphid-like insects that attack and kill hemlock trees. Symptoms are the following:
- White "woolly" sacs that resemble tiny cotton swab ends at the base of hemlock needles on young twigs; these are most obvious in the spring
- Premature bud and shoot dieback
- Premature needle loss
- Thinner, greyish-green crown (healthy crowns are a shiny, dark green color)
- Dieback of twigs and branches
- Discolored foliage
- Death within 4 to 15 years
Scab and Rust Diseases
Rust disease first appears as small, yellowish-orange to reddish-brown flecks on grass blades and develops into raised pustules on blades and stems. Pustules are oval or elongated and contain powdery masses of yellowish-orange to reddish-brown spores. As the pustules mature, they turn from brown to black, and the heavily infected turf becomes thin and yellowish-orange to reddish-brown. Infected blades eventually turn yellow and die.