COMMON PEST AND DISEASE

COMMON PEST

Spruce Sawfly

- Spruce Budworm - This pest attacks spruce and fir trees by the larvae attacking the new buds of the tree, causing devastation to the tree limbs and foliage. This defoliation can cause the entire tree to die.

Leaf Roller

- Aphids - These insects are plant feeders, which feed on the juices inside the plant. There are many species of aphids, which feed on many different types of plants and trees. These aphids can attract other insects, such as ants to your yard. As well, they can be a vector for certain diseases (fungi, viruses, bacteria). See above for some of the kinds of diseases we see frequently. In large numbers, aphids can weaken a tree, and cause damage to leaves and branches. If the tree is already in a weakened state, aphids can be detrimental.(Click Here to view Image)

Spider mite

- Borers - There are many types of borers, some are introduced species such as the Emerald Ash Borer (Click Here to view Image), and others are endemic. They will bore into the tree’s bark, and can cause damage to the parts of the tree responsible for the transport of water and nutrients to the other parts of the tree. This can cause damage to sections of the tree, or in large numbers, the entire tree. These can be difficult to kill, as they are protected by the bark from insecticidal sprays. (Click Here to view Image)

- Leaf miner - This group of insects eats its way through the leaves, inside the leaf itself. This causes damage to the leaf, which kills the leaf. In large numbers, many of the leaves can be destroyed and the tree can be weakened. In an already weakened tree, this can be enough to kill the tree. Since they are inside the leaf, pesticide sprays aren’t effective. This is where a systemic into the tree will work better. (Click Here to view Image)

- White Pine Weevil - This pest can cause great damage to your tree. The larvae hatch and bore into the leader of the tree. This girdles the top and kills the tree’s leader. Symptoms of this pest include the deformed branches, reduced height of the tree, and rarely tree death. (Click Here to view Image)

- Tussock Moth - The larvae of this moth feed on the ends of firs and Douglas-Fir trees causing them to shrivel up. Not only does this look unsightly, it causes weakened trees. These pests can top kill the tree, or even the tree itself.

COMMON DISEASE

Fireblight - This bacterial infection causes death of a tree, and is very infectious. This affects pear, apple, crab-apple, quince, hawthorn, raspberry, and other rose family trees. It is identifiable through the appearance of the tree which appears as though it was set on fire: blackened, shrunken, cracked areas on the tree. It begins as wilting and blackening/browning of blossoms and leaves on the terminal shoots. This can spread throughout the tree. There are not any cures to this – the infected area should be fully removed, or the tree should be destroyed to prevent infection spreading to other trees.

Summary:
- Bacterial disease
- Attacks the rose family including pear, crabapple, cotoneaster, mountain ash, hawthorn, spirea, rose, and, raspberry
- Most susceptible are pears
- Symptoms are wilting and blackening/browning of blossoms and leaves on the terminal shoots
- The bark blackens and cankers develop on the older, larger portions particularly at the margins between living and dead tissue
- A brown ooze is excruded at the site of the cankers especially during warm, moist weather
- Sanitation is to prune infected areas 10”-12” below the last observerable symptomic area, and disinfect tools with bleach after each cut
- Do not use high Nitrogen fertilizer
- Application of bacterial sprays during the dormant season and at flowering time have been effective for control
- Plant-sucking insects are known to be a strong causal agent
- Bordeaux Mixture: 1 part copper sulphate (blue stone), with 1 part slaked lime (calcium hydroxide) in 100 parts of water has proven effective in some cases (Click Here to view Image)

Black Knot - This fungal infection causes rough black patches on cherry, plum, and apricot trees. This kills infected branches, and if left alone can kill your tree. It is best to cut away the infected branches so it doesn’t spread. (Click Here to view Image)

Slime Flux/Wet Wood - This occurs when a cut on the tree fills with bacteria and causes slimy ooze which eats into the tree. This weakens the tree, making it more susceptible to insect damage and other diseases.

Needlecast - This fungal pathogen of Douglas-Fir trees causes the needles to discolor and eventually fall off of the tree. In the spring and early summer, this can start to be seen. There isn’t a treatment; however providing deep root fertilization can be helpful for the tree’s immune system. This helps the tree to help fight this.(Click Here to view Image)

Cankers - These abnormal tree growths can be caused by a number of pathogens. Some are relatively harmless, but some can be detrimental to a tree. In either case, the tree becomes weakened. (Click Here to view Image)

Corkscrew Virus - This viral attack causes the tree to grow in a ‘corkscrew’ shape along with turning the tree’s needles yellow, and then a red-brown. This affects coniferous trees such as spruce.