Tips for Summer Tree Care
Monday, July 09, 2012
Summer is good for pruning
Summer, on the other hand, is good for pruning the spring flowering trees and shrubs whose blooms have all but ended for the year. Trees falling into this category include the Eastern Flowering dogwood, crabapples, cherries, and magnolias. Eligible shrubs are the weigelas, deutzias, lilacs, azaleas and rhododendrons. Improve plant structure by eliminating co-dominant stems, forked branches, suckers, and any crossing and rubbing branches.
Summer is also good for selectively pruning branches to thin out the crown of any dense, thickly foliated plants. Pruning increases air circulation and sunlight penetration. The latter triggers new shoot development on the lower stems of shrubs, preventing them from becoming “rank and leggy.” When pruning, remove no more than 15 percent of the total live wood of any plant during the pruning operation. This rule helps conserve the stored carbohydrates the plant needs for further growth and development.
A good time to mulch and water
Summer is also a good time to mulch and water plants. High temperatures (above 75 degrees F.) retard plant growth and can lead to drought stress. Apply a layer of mulch over the roots of trees and shrubs before the sweltering heat arrives. This will help maintain soil temperatures—between 45 degrees F. and 65 degrees F.—conducive for summer root growth.
Mulching also reduces excessive loss of soil moisture through surface evaporation. New and established plants should never go more than 14 consecutive days in the summer without water. Supplement natural rainfall in the summer with water buckets or hoses when the soil becomes too dry to support good plant health.
The next six weeks or so (until about July 31) are also a busy one for insects and pests that prey on plants. Plants will be working hard to create and store as much "food" as possible within their woody tissues, using photosynthesis. Pests, on the other hand, will be actively feeding on plants so they can accumulate enough energy to complete their annual life cycle. Given this scenario, a successful outcome for both species is doubtful.
For plants to survive, they must to be properly maintained and monitored for pests. Contact UMass' Extension Agriculture and Landscape Program for a list of the worse pest offenders for this time of year and the plants they’re most likely to damage. Many of the treatments needed for pest control require the use of commercially available registered pesticides, so seek the consul of a certified arborist to help devise an effective management strategy for problem pests.
For more information on summer plant pests, go to www.umassgreeninfo.org.
John Campanini is technical director of the Rhode Island Tree Council. Previously, he was Providence’s city forester
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