Now that leaves have fallen from trees and shrubs it's time to wander through the garden and access the pruning requirements of our woody plants. Dead branches need removed, something that might not be so obvious, check by bending the branch to see if it breaks with a snap. Crossed branches are also a good place to prune, removing the worst offenders, essentially leaving an open network of interior branches. A yearly pruning will save you from the future problem of dealing with insects that have entered damaged wood and also help maintain a good shape on trees and shrubs as they mature. When this is handled regularly there is no need for a chain saw, just a good pair of pruners or a hand saw. Trees like Japanese maples, redbuds, magnolias and dogwoods respond beautifully to yearly maintenance.
When removing a tree limb, it is very important to cut just beyond the branch collar so that the wound will heal properly. The branch collar is an area of tissue containing protective chemicals that heal over and provide a barrier against boring insects. If you look closely you will usually see a small bump or ridge that circles the base of each branch. Cut at the top of the limb, just beyond the ridge, but don't cut all the way through until you have cut some from the bottom, an inch or so into the limb. This keeps the falling weight of the branch from ripping off bark as it falls.
Shrubs that are routinely sheared will also benefit from periodic thinning. The removal of dense, inner branches in shrubs such as boxwood will promote air circulation and encourage healthy growth. The practice of plucking boxwoods or thinning inner branches can be done anytime in the winter, many professionals time it so that boxwood clippings can be sold for use in holiday decorations.
You can also take advantage of the winter season with an inspection for insects. Boxwoods often suffer from leaf minor and/or mites which become more obvious with the onset of cold weather. The leaves will look yellow, blotchy with leaf minor problems and speckled from mites. The boxwood leaf miner winters over inside the leaf and resumes its feeding in spring. Insecticidal soap can be sprayed once the feeding begins with warmer temperatures in March and April. The mite will over winter as an adult, a November application of a light horticultural oil is recommended, applied when temperatures are 45 degrees or above.
The deciduous magnolias can get scale which is easily seen once the leaves have dropped. Small, peppercorn size lumps will cover branch or trunk. If you noticed an unusually high incidence of bee activity around your magnolias in summer, chances are you have scale. The bees are drawn to the honeydew secreted by the females in June and July. A dormant oil spray can be used during the winter months, applications can be made in November and again in March.
November brings us shortening days and a lessening of tasks in the garden, but with good timing a few things can be dealt with to halt future problems.
If your containers are looking a little weary, I will be giving a free demonstration on winter containers at Merrifield Gardens in Gainesville this Saturday, November 17th at 10:00 AM.
http://www.merrifieldgardencenter.com/Gardening-Seminars/Free-Seminars/Winter-Spring-Seminar-Schedule.aspx