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Tree Care through the Year

Compiled by Kristin Ramstad, Urban Forester, for the 2009 Yard, Garden & Patio Show
Oregon Department of Forestry - 503-945-7390

(1)  Many of these recommendations were compiled from OSU Extension Service "Garden Hints" lists OSU Extension encourages sustainable practices, advises identification and monitoring of problems before acting, and to always consider the least toxic approach first. Trade-names are mentioned as illustrations only, and should not be considered an endorsement. For specific questions regarding your region please contact your local extension office.

(2)  Fruit and nut tree information is included for home orchardists and individual fruit tree owners, but will not be covered in detail in this presentation. Landscape tree info is listed in BOLD italic font; orchard tree info is listed in
normal font.


  • Water plants below wide building over-hangs that limit rain reaching those areas.
  • Make sure mulch and leaves are not built up at base of trees. Field mice can nest in it, and girdle/harm trees by nibbling at bark.
  • In areas of high, freezing winds: place wind-breaks to reduce possibility of evergreen wind-parch (drying of foliage)
  • Plant deciduous fruit and specimen trees on 'warmer' days
  • Watch for snow or ice build-up on trees and shrubs. Sometimes a good shake will save a prize plant.
  • Hardwood cuttings of ornamental trees can be taken for propagation.
  • Fruit trees arrive late this month in nurseries. You will find these are less expensive or of better quality than those from mail order sources or in discount stores.
  • Spray cherry trees for bacterial canker with a dormant spray. Lime sulfur or copper fungicides (with spreader-sticker) help control diseases. Removing leaf debris underneath the plant will also help.
  • (Mid-month) Spray peach trees with approved fungicides to combat peach leaf curl, or plant curl-resistant Peach cultivar 'Frost'


  • Plant trees — especially bare root and "Balled and Burlapped" (B&B) ornamental and fruit trees.
  • Prune late spring–to–summer-blooming ornamental trees.
  • Prune maples, birches, elms, and oaks.
  • Repair winter damage to trees, keeping Natural Target Pruning concepts in mind.
  • Fruit trees can (still) benefit from delayed dormant sprays of lime sulfur.
  • Prune fruit trees. Young trees need scaffold limb selection. Old trees need size and weight control plus space for sunlight.


  • Prune early–blooming ornamental trees after they have finished blooming.
  • If necessary, fertilize evergreen trees.
  • If necessary, spray shade trees for webworms and leafrollers.
  • If necessary, spray to control leaf and twig fungus disease in sycamore, hawthorn, and willow trees.
  • Graft fruit and ornamental trees (with scion wood).
  • Young trees and shrubs may benefit from spring fertilizer application now. A general fertilizer, whether organic or inorganic, is fine. Apply specific applications as per plant type, and do it again later in May.
  • Last day to prune elms (and possibly oaks) is March 15


  • Oregon ARBOR WEEK is the first FULL (Sun to Sat) week in April; National Arbor Day is LAST Friday in April. Tree planting focus should decrease as season warms up.
  • Wet, cool weather promotes leaf disease in dogwood trees, apples, cherries, and roses. Early detection and early treatment with fungicides may be necessary. Dogwoods can be treated to prevent anthracnose with copper fungicide or Daconil. Raking and destroying fallen leaves spring through fall will reduce severity of disease.
  • Prune early spring–flowering trees that have not leafed–out yet.
  • Spray for apple scab, cherry brown rot, and blossom blight.


  • Control aphids with insecticidal soap, a hard spray of water, or hand removal. For problem cases, use approved and labeled pesticides.
  • Irrigate young trees if necessary as season becomes dry.
  • Spray cherries, plums, peaches, and apricots for brown blossom rot blight, if necessary.
  • Set out pheromone traps to detect coddling moth in apple orchards.


  • Mulch trees to conserve moisture, provide protective area around tree base, discourage weeds, minimize soil heat fluctuations, etc.
  • Birch trees and lindens that are "dripping" honeydew are harboring aphid infestation; treat as needed.
  • Begin to notice signs of stress from construction damage or root complications. Start remediation strategies, if necessary/possible.
  • First week: Spray cherry trees for cherry fruit fly and brown rot if fruit is ripening. Spray for codling moth if detected in apple and pear trees. Continue to monitor for codling moth.
  • Rake and destroy leaves that are falling off of apples and pears as these may be an indication of susceptibility to Scab disease. Several spray options are available to control disease – contact local Extension resources for information.
  • Fruit trees drop excess in June. Afterward, you should thin by hand those left to protect limbs and produce larger fruit. Thin apples and pears to one or two fruits per cluster; peaches and plums to 8 inch spacing. Place traps in apple trees to detect codling moth emergence. Expect fruit flies in cherry trees with fruit.


  • Watch for signs of stress in trees due to construction damage, drought, competition from other plants, and tough growing locations (e.g., parking lots).
  • Water wisely. Plants in containers might need water every day, but plants in the ground do better with a deep watering weekly or twice a week instead of a little water every day or every other day. New plants in landscape need special attention. Deep water new trees and shrubs.
  • Many treatments for orchard trees: treat filberts for filbert-worm; peach and prune trees for root borers; spray again on apples and pears for coddling moth; trap adult apple maggot flies.


  • Long hot days require attention to watering. Avoid summer stress on new trees with deep watering. The first summer is the most difficult for new trees and shrubs. Good soil and mulch help reduce water needs.
  • Moderate pruning of trees, including new growth on fruit trees, will lessen the winter chores. Pruning now reduces the total height without stimulating quick re-growth as often happens in the spring. Also, pruning wounds heal much faster in warm weather. This is especially true of junipers, which should never be pruned during wet weather.
  • Trees and shrubs new this year to the landscape should be watered deeply. Often new plants fail among old plants because the increased need is not observed until too late.
  • Check and deal with those apple maggots again, if necessary.
  • First week: orchards spraying again – for walnut husk fly; for root borers in peach and prune trees; for filbert-worm, etc.


  • September into late October is an ideal time to plant lawns, trees and shrubs, ground covers, hardy perennials, even bulbs for spring bloom. Cooler weather puts less stress on the leaves, but the soil is warm enough to encourage root development.
  • Copper spray for peach and cherry trees.


  • Trees and shrubs, ground covers, hardy perennials, and especially bulbs for spring blooms (such as tulips and daffodils) should be planted this month. Nurseries and garden centers often stock up for the “Fall is for Planting” season and Le Tour des Plants (
  • Last half of the month: elm tree pruning OK until mid-March.
  • Spray stone fruit trees.


  • Wrap trunks of trees that are exposed to low–angle sun from south–southwest with paper tree wrap late in month to protect against sun scald.
  • This is a good time to plant trees and shrubs.
  • Early in the month, go foliage shopping! Trees and shrubs that produce beautiful fall color will be displayed in garden centers.
  • Protect tender evergreens from drying winds.
  • Rake and destroy leaves from diseased fruit and dogwood trees; removed mummified fruit from fruit trees.


  • Do not forget the plants under the eaves or under large evergreen trees. These locations could be too dry, despite lots of rain. A dry plant will suffer more during very cold weather. If you use a hose to water, be sure to drain both it AND the nozzle.

References and useful websites:

Oregon Department of Forestry – urban forestry page:
This is your "one stop shopping" site for a variety of tree care links and other urban forestry websites.

Pruning trees:
This is one of my favorite websites for pruning information.

Fertilizing trees:
An excellent and comprehensive article on fertilizing trees. - or Google: "Landscape Plants + University of Florida". This is Ed Gilman's site at the University of Florida, and it is such a good resource, it is almost all you need. It has PowerPoint presentations on all sorts of topics – from trees and infrastructure to planting wind-firm trees; it has design plans for residential yards; it has a huge list of tree fact sheets...and much more. The only drawback is that its perspective is from Florida – but there is still a lot of info on trees for northern climes. - or Google: "Trees are good". This is an excellent site developed by the International Society of Arboriculture (ISA) for the non-arborist user. ISA has produced a full set of tree care brochures that it has made into PDFs on this site. – or Google: "Urban Forest Ecosystems Institute". This site is home to SelecTree. You can enter attributes you wish to find in a tree into its database, and the site will spew out a list of trees that fit those criteria. The site also has a California native tree disease and pest database, as well as a database of mills and manufacturers that process urban trees. UFEI is based in the College of Agriculture at California Polytechnic State University, San Luis Obispo, California. It was developed by the Natural Resources Management Department faculty to address the increasing need for improved management of the urban forests in California. - or Google: "American standards for nursery stock," One of the early activities of the American Nursery & Landscape Association, formerly the American Association of Nurserymen, was the development of a standardized system of sizing and describing plants to facilitate the trade in nursery stock. Since 1921, the Association has maintained an active committee on standards.

Google: "ANSI A300 Standards for Tree Care Operations" – these are the nationally-recognized tree care standards used by Arborists.

PlantAmnesty -- For a humorous and educational take on tree and plant care, check out this site! Founded by Cass Turnbull in Seattle over 20 years ago, this non-profit has spread the word about the perils of topping and other bad plant practices to thousands of citizens. Make sure to visit the Madness Gallery of photos, and take their pruning and tree care quiz!

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