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Blackberries, Orchids, Pruning & Birch Leaf Minor

About pruning blackberries; how to grow a Cymbidium orchid; pruning rhododendrons and apple trees; and birch tree insect problems!
by Art Drysdale
by Art Drysdale

email: art@artdrysdale.com

Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at http://www.artdrysdale.com


April 29, 2007

Above, our min-pin Winston in front of one of our Cymbidium orchids in our Toronto living room; below, Crimson frost birch with gorgeous mauve foliage is just one of the many birch trees that can be affected by the bronze birch borer. Author photos. At bottom, typical damage as will be first noted when bronze birch borers are present. Photo by Bill Remphrey, courtesy of the University of Manitoba.

A caller to my AM740 radio programme on Saturday April 21 asked about the pruning of blackberry bushes. I had to tell her that blackberries were one fruit with which I had no personal experience, and thus reluctant to offer pruning advice. I did say I would check with my colleagues and report on the 28th, and here is my report.

Blackberries, somewhat like raspberries, about which I have written many times, produce fruit on canes that were formed the previous year. The canes that produce the fruit are known as floricanes. After fruiting, the floricanes dry up and die and should be cut down to ground level. The new growths each year are called primocanes and they will bear fruit the following year. In the spring, soon now, it is advisable to tip back all the new canes as they get to a height of about 60-75 cm (24-30”) to about half that height. This tipping back encourages the production of more lateral growths which will then give you more flower buds, and hence fruit. The tipping back should be performed as early as possible in the season so as to ensure that the flower bud initiation process is complete prior to the onset of dormancy. Ideally in a healthy blackberry stand, not unlike as recommended for raspberries, five to six canes should exist per 30 cm (foot) of row and blackberries can form a solid hedgerow.

Giuliana Camelia of Niagara Falls wrote on April 19: “I recently bought a beautiful cymbidium orchid plant with many spikes and blooms. It is in a 6" pot. I am very confused about the best care and maintenance of this beauty. Many florists have given me all different instructions. It was an expensive plant {70 dollars}. I would really like to give it a place in my home. I understand you are the expert in the care of most any plant or tree. Would really appreciate your time and opinion. Thank you.”

My response to her was as follows: “Though we had three or four gorgeous cymbidiums at our Toronto home, somehow we gave them all away and did not bring any with us! We kept them in a cool greenhouse, facing west, and they always bloomed in the spring, earlier than now. In the summer we used to put them out on the deck beside the greenhouse, on the floor and fertilized them well. We had to divide them up about every three or four years.”

My suggestion is that you contact Doug or Terry Kennedy who run Orchids in Our Tropics in Gormley, north of Toronto, and possibly plan to visit them when you are in the Toronto area. Their number is (905) 727-3319, and email address: ourtropics@sympatico.ca. Thanks for your interest.”

Tracy Atwell, from somewhere on Vancouver Island wrote on April 17, asking about pruning, as follows: “My name is Tracy and we have just bought an 18-acre piece of land. Three acres have been transformed into a Butchart Gardens, it is so beautiful. Over 700 rhodos, magnolia, dogwood the list goes on. We have an apple orchard with many different varieties. Should I let them go for a year or try to prune them now with blossoms on them? How about the rhodos, some have been let go and are quite overgrown. Maybe you know of this property the Paul’s have made this a beautiful place. He was with the rhodo society. If you could give me some suggestions I will be appreciative. Thank you.”

My response, which applies generally to others in similar situations, was: “You obviously have quite the tasks ahead of you. Though others might suggest alternate approaches, I would prune neither the apple trees nor the rhododendrons now. I would leave the apple pruning to about July, and then prune fairly heavily, including, of course, all of the upward growing so-called water sprouts. The centres of the trees should be bare when you are finished.

“The rhododendrons are best pruned immediately after they bloom. You can be quite ruthless if you wish to reduce their size, but be sure you think about each plant as an individual before you begin to prune it. If you don’t wish to reduce any particular plant’s size, then you should just prune off the old flowers being very careful to prune only the flower head, and NOT the new buds beginning to develop at the base of the old flower head. Be sure you see these in every case before you prune away the old flower.

“Fertilizing the rhodos is another matter and that too should be done through the summer starting as soon as the flowering is complete.

“You might find it a good investment in time if you visited one of the Rhodo society sales or tours and talked with some of their members. Thanks for your interest.”

Last week, on Monday, Dave Ortiz in Brampton wrote about a very common problem these days: “We are quite desperate to save our birch tree. We just purchased this house a few months ago and have found out that our 20' birch tree has bugs. Our neighbour is calling them leaf minor bugs. He says that since Cygon was banned we can not do anything about them. Can you please let us know asap if there is anything that can be done. Time is of the essence as the tree looks sick.”

The removal of Cygon from the market was a blow to the control of the birch leaf miner, for certain. There are two points to be made. First, there are at least three chemicals which may still be used in Canada, as far as I am aware. They are malathion, sevin (carbaryl) and permethrin. Doktor Doom sells the strongest form of permethrin (50%), again, as far as I know. The tree should be sprayed with your choice of chemical at about the time the leaves are half unfurled (not half the tree, but half of each individual leaf). The spray should likely be repeated at least one more time in about five to ten days. If you go without rain after the first application and you are able to use the Doktor Doom product, either the 50% or the 25% permethrin, it should be residual enough to last longer than five or ten days.

You may also have a problem with bronze birch borer; especially since you say the tree is “sick”. The leaves are surely not all out yet and I wonder what makes you draw that conclusion. The borer insect cannot be attacked with any insecticide! It is a case of cutting out the dieing upper limbs when they are first noticed with browning leaves. If that is not done, the borers spread down the limb (it always starts at the top) and soon kill the entire tree. The two insects are not related, but often a couple of years of infestation by the miners, will cause the tree to stress more than usual and lead to the onset of the borers.

One additional suggestion would be to fertilize the entire tree (covering all the foliage) with at least one application of a 10-10-10 product such as BioTLC’s Liquid Growth Plant Food 10-10-10. I would put that on asap, and follow up a day or two later with the insecticide.

I hope you can save your tree.

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