Horticulture Guy

Q. My neighbor has a lovely red Norway maple. The city inspector wants to cut it down saying it has wilt infestation. To me it looks very healthy. It is about six or seven years old. How does the inspector determine this kind of disease and how can get evidence? I do not want the tree cut if it has a chance to survive. Isabella Kates - Ontario, Canada

A. They have probably diagnosed Verticillium Wilt.  Usually you see outward signs of stress first, like reduced leaf size or wilting of leaves when there is no drought.  The strongest indicator is then looking in at the wood, which usually becomes discolored from the infection.  Your own University of Guelph has a very nice document http://www.uoguelph.ca/pdc/Factsheets/PDFs/007VerticilliumMaple.pdf  on the disease which should help you solve this yourself.  At least you will be able to converse with the city inspector and have some knowledge of what he is talking about. 

-- HG

Q. It’s my first winter in my new “established” house. Lot’s of free standing bushes which I know all flower in different times of the summer, don’t know what they are but they have become overgrown and I have no idea when to prune them or how much.  There are forsythia, taller then a person and the two other major bush growths are 15 to 20 feet high and I would like to get them down to about 5 ft or so any suggestions, based on the info I have provided?  Thanks Sandy - Vernon CT

Without knowing what the other species of shrubs are it is difficult to tell you how to prune them and what type of pruning (e.g. drastic) they will tolerate. Many shrubs have their own genetic predispositions.  I can say that if they are flowering shrubs and you do not wish to loose a season of blooms you will want to prune early blooming shrubs immediately after they bloom since they bloom on old wood where flower buds form.  Later blooming shrubs have a larger pruning period, which includes the dormant season, since the flowers will develop on new season’s growth.  Your forsythia will take some heavy but judicious pruning.  It flower buds grow on old season growth so take that into consideration when pruning.  I would suggest either finding a book on pruning shrubs or checking out the University of Connecticut’s Home and Garden Education Center website: http://www.ladybug.uconn.edu/ for more information.
 

-- HG

Q. I have an apple tree about 15-20 yrs old. It bore lots of healthy fruit, but I couldn’t reach 3/4 of it. I don’t think it has ever been pruned. I know which limbs to take out, but how aggressive can I be, and when should I prune? Also, can I cut back the length of the branches, or the height of the tree? I miss your column, but am glad to find you online. Thanks! Marty Fisher, Orting, WA

A. Actually you can be fairly drastic especially with any vertical growth but as you guessed timing is important.  Since you seem to be familiar with what the shape should be (I know which limbs to take out) I’ll just reiterate for others that may read this.  The best shape for the apple is to have an open center.  So your goal is to open up the center and thin things out so that light can get into the center of the tree. Pruning now would likely result in loss of fruit this coming season and possible overgrowth of new shoots since the tree will have the energy it would have used on fruit production on new excessive growth. Vertical branches bear less fruit than more horizontal ones so a few of those could be removed now in the dormant season. I would wait until you see the fruit set in the late spring and then go in and get that tree back into shape being sure to leave a crop of apples to enjoy.

-- HG

Q. Yes I miss your column. I’m looking for recommendations of native trees to plant on our parking strip, which is on the North side of the house.  These are to replace the two matching winter flowering Japanese flowering ones I need to have removed because one has died. I think natives will have a better chance. Lily Warnick - Gig Harbor, WA

A.  Well since you say that the strip is on the north side of the house I will assume that it is either a shady or partially shaded area, which limits the number of native trees that would be appropriate.  If you would like to stay in the cherry genus there is a native Bitter Cherry (Prunus emarginata var. mollis), which may be suitable.  Be sure not to get the “var. emarginata” which is more spreading and shrub like.  Although the flowers are not quite as showy the Cascara or buckthorn (Rhamnus purshiana) is another option if the soil is on the moist side.  A Pacific Dogwood (Cornus nutallii) is another showier alternative although it is somewhat susceptible to the fungal disease anthracnose.  Breeders are actively working on disease resistant varieties of this. 

-- HG