Here are the top Ten Tree & Shrubs Insects and Diseases problems. (Actually ithere are eleven, but that's pretty close to 10.) Remember to keep your trees & shrubs well watered in dry weather. Good nutrition is also important. A healthy tree is better able to resist insects and diseases. We recommend deep root feeding in the fall to make sure that nutrients are available to the plants when needed.
1. Euonymus & Magnolia Scale - See Scale Insect Factsheet
2. White Birch Trees - The Birch LeafMiner and Bronze Birch Borers. See Birch Care Factsheet
3. Honeylocust Leaf hopper -- Locusts such as Shademaster and Sunburst can be attacked by Leafhoppers. These are small green wedge-shaped bugs. They suck the sap from the leaves, often discolouring and disfiguring the leaves and stunting growth. They can also transmit virus diseases. Control with foliar sprays of Insecticidal soap or Acecaps.
4. Gypsy Moth Caterpillar - These caterpillars are dark and hairy with a double row of 5 pairs of blue and 6 pairs of red spots from head to tail. They feed on many tree species. Favourites include birches, lindens, crabapples, mountain ash, willows, oaks, blue spruce and many other trees. Voracious feeders, these caterpillars have been known to defoliate trees. Remove egg masses. Trap caterpillars by tying a band of burlap around tree trunks. Inspect daily and destroy caterpillars. Use Acecaps or foliar treatments to prevent damage. See the Gypsy Moth Factsheet.
5. Cedar Leaf Miner - Cedars with Leaf Miner have brown tips on their leaves. During June and July tiny grey moths take flight when the branches are disturbed. Damage is usually worse on the lower branches. If possible trim before June, then destroy the clippings before the adults emerge. See the Cedar Leaf Miner Factsheet
6. Diseases Problems - In general, rake and remove leaves and fruit each fall to reduce sources of disease. Flowering Crabs are susceptible to powdery mildew, scab and black spot fungus diseases. Prune to increase air movement. Treat with a fungicide in late May-early June. Insecticides should be applied at the same time. Hawthorns suffer from leaf spot and rust disease. Treat hawthorns with fungicide just after flower petals fall. Catalpas, lilacs, honeysuckles and maples are attacked by powdery mildew. Proper timing is difficult with powdery mildew, but treatments usually reduce the severity of the disease.
7. Viburnum/Snowball Insects - Aphids suck the sap from leaves and disfigure them. Viburnum leaf beetle (larvae and adults) will skeletonize leaves. Use foliar sprays such as Insecticidal Soap to control. Usually more than one treatment is necessary.
8. Spruce Gall Aphids - Actually an adelgid (close relative of the aphid). The pest can cause the spruce to form galls near the growing tips. The galls result in slowed growth, sparse branches and distorted growth. Removing galls when they are still green (before mid-July) will help slightly. Treat with foliar spray in late September and October. Spring treatments are less effective as timing is more weather dependent.
9. Fruit Trees - Rake and remove infected leaves and fruit each fall. We recommend starting with a Dormant Oil treatment. Orchards treat fruit every week but in home orchards we recommend about 2-3 foliar applications of insecticide/fungicide.
10. Pines - Austrian and Mugho Pines are often attacked by sawfly larvae. These interesting caterpillars will move in unison. They can quickly defoliate branches but are relatively easy to control with an insecticide application. Pines occasionally get scale insects as well (see Scale Insect Factsheet)
11. Tent Caterpillars - The Easter tent caterpillar form tents in the crotches of limbs of apple, crab, cherry, and other deciduous trees and shrubs in the spring. Fall webworms spin large webs over the branch tips in August and September. Prune out and destroy the tents if possible. Insecticidal soaps can be effective if the tents are thoroughly soaked.
12. Many other insects and diseases can affect your trees and shrubs. Please call for a consultation.
If you have a lawn/tree/shrub that needs some Tender Loving Care- get The KING OF GREEN: