Calendar — The Tree Doctor

Common treatments and activities are listed by month to assist you in planning care for your trees and shrubs throughout the season.

Pest Patrol #1 - Dormant oil spray before trees and shrubs leaf out to kill overwintering insects and their eggs before they hatch.
Early Spring pruning - clean out deadwood and entangled, crowded growth to improve light and air penetration and reduce insect and disease habitat. Remove diseased, broken, weak, crossing, or rubbing branches to create proper structure for future growth. Remove any whole plants or sections excessively damaged by winter conditions.
Compost and mulch for fertility - Spread mushroom compost or leaf mulch for fertility in landscape beds, across lawn, and under trees. Also spread 2-4 inches bark mulch to protect trees from soil compression, excess evaporation, and mower/trimmer damage. We use premium natural bark mulch only to add nutrients and avoid the chlorosis that often results from common wood-chip mulch.

Pest Patrol #2 to control newly hatched spring insects and cool-season mites. Preventative insecticide sprays should be applied to cherries and other ornamentals with damaged bark or exposed heartwood to protect trees from wood-boring insects. Systemic insecticide treatments for common problems like scale and adelgid are most effective in the spring, as the insect populations are just beginning to build up.
Spring pruning - selective pruning to improve health, structure, and appearance of shade and ornamental trees and shrubs.
Compost and mulch in bare landscape beds and around ornamental trees
Deep-root fertilizer injections for trees and shrubs needing additional nutrients to support growth.

Pest Patrol #2 - Spring insect (adelgid, scale, leaf miner, aphid, lacebug) and mite treatments
Late spring pruning is ideal for needle and scale-leaf evergreens, which need frequent, light pruning touch-ups to keep them cut back from driveways and walkways if they are planted too close. May is a good time to shear boxwoods and privets, and is the ideal time to prune spring-blooming plants after their blooms have finished: azaleas, rhododendrons, lilacs, forsythias, dogwoods, crabapples, most roses.
Tick and mosquito treatments (tick tubes, mosquito larvicides, natural sprays) are are timely in May when tick and mosquito populations are exploding because of the warming weather.

Pest Patrol #3 - Early summer insect (aphid, caterpillar, Japanese beetles, scale, adelgid) and warm-season mite treatments. Caterpillars and Japanese beetles both become active in June and do heavy damage to leaves, but can controlled with nontoxic biopesticides if they are treated in time.
Early summer pruning - General selective pruning on trees and shrubs to control and direct growth. Prune birch after fully grown in. Shear boxwoods and privets again if necessary. Deadhead flowers. Prune any overgrown herbaceous plants.
Emerald ash borer trunk injections - Emerald ash borer has become so widespread in North America that almost all remaining ash trees are alive because they are being treated with insecticides, or are still too small for the borers to

Pest Patrol #4 - Summer insect (aphids, caterpillars, Japanese beetles) and warm-season mite treatments. Bark disease treatments for beeches and other vulnerable species or infected trees.
Summer pruning of any trees or shrubs that need it to tame excessive growth.
Deep root-fertilizer treatments with supplemental micronutrients to support trees and shrubs during summer drought stress. The additional water from the fertilization is helpful as well; supplemental watering for drought-stressed trees and shrubs can prevent bark damage from dessication/cracking. Cracks in the bark become an entry point for fungal spores and can lead to bark disease and eventual tree decline/death.

Pest Patrol #5 - Late summer insect (fall webworm) and warm season mite treatments.
Late summer pruning to manage excessive growth
Monitor apples, pears, crabapples for leaf diseases. Clean up prematurely dropped leaves to reduce re-infection in future seasons.
Monitor trees for premature leaf drop, a common sign of trees in distress

Pest Patrol #6 - Late season insect and cool-season mite treatment / dormant oil treatment
Fall tree and shrub planting - fall is the best time to plant!
Fall cleanups: post-growing season pruning of overgrown trees and shrubs and removal of dead or damaged tree tissue, particularly cankered branches and leaves with foliar disease that harbor overwintering spores that will re-infect new growth in the coming Spring.
Fall tick and mosquito treatments - tick tubes, larvicides, sprays
Fertilization - post-season deep root fertilizers to build nutrient reserves of soil and prepare trees for spring growth.

Last chance for tree and shrub planting!
Final fall clean-ups
Winter deer treatment #1 for deer-edible evergreens
Winter anti-dessicant treatment #1 for broad-leafed evergreens whose leaves can easily dry out and die during the harsh winter months (high wind, cold) while the ground is frozen. Particularly useful on laurels and hollies or any newly-planted evergreen that has not had a long time to develop its root system.

Dormant pruning is ideal for most deciduous trees and broadleaf evergreens, especially species that are susceptible to fungal infection when pruned in spring or summer (oak, ash, elm). Prune summer-blooming plants (potentilla, butterfly bush, crape myrtle) when dormant to maximize next-season bloom. Prune shrubs without showy blooms like barberry and burning bush. Prune fruit trees and bush berries (blueberries, gooseberries, currants). Prune hollies, magnolias, and mahonias.
Risk reduction pruning to remove dead or damaged branches and compensate for structural flaws is highly advisable on large trees near structures. Proper risk reduction pruning and tree cabling can significantly reduce risk of tree failure during high wind/winter storms. Tree removals can eliminate this risk entirely.
Winter deer treatment #2 for vulnerable evergreens in January or February.
Winter anti-dessiccant treatment #2 for broad-leafed evergreens in January or February.