TREES & SHRUBS

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We help gardeners by answering questions, contact us at ask@mgmanitoba.com

Q&A Topics
Pruning dwarf sour cherry shrubs (Juliet)
Identifying bronze birch borer
Hardiness of Calgary boxwood shrubs and lacecap hydrangeas
Pruning mock orange shrubs
Protecting a hybrid tea rose
Aphid infestations and thrips on lilac shrubs
Recommendations for compact deciduous trees for small yards
Can small trees and shrubs grow in raised garden planters?
Can yard plants recover from defoliage from elm-tree worms?
What types of insect rolls leaves on trees?
Pruning tips to espalier apple trees
Causes of shrivelled leaves on crab apples

How to care for and fertilize hydrangeas
Pruning a cracked branch on a mature Amur maple
How to care for and fertilize hydrangeas
Fall protection for hardy roses
Encouraging fruit producution on Jostaberry bushes
What causes “cupping” on lilac leaves?
What causes leaf drop-off on established roses?
Suggestions for planting roses near a concrete foundation
Can hybrid tea roses survive the Zone 3 winter?

What caused shrubs not to shed their brown leaves in fall?

 

Question: Pruning dwarf sour cherry shrubs (Juliet)

This is my 3rd summer with this Juliet cherry shrub. I’m growing it as an espalier along a fence and it gets 8+ hours of sun. The soil is great and rich in compost. I grow strawberries under as a ground cover/mulch. I prune the lateral branches twice a year in late winter and after it puts on a new spring flush of leaves. The tree looks very healthy. I prune back leaving two leaves on each spur. This year I was really expecting flowers but not a bud was in sight and now I know they’d be done blooming. There should be one, two and three year old wood for fruiting. Any ideas what I should do different to get fruit on it? I assume I’m pruning incorrectly but I can’t find anyone who has espaliered a hardy cherry to ask what pruning schedule is best. Maybe it’s stressed from too much pruning? I live in Winnipeg.

Answer:

You have created a beautiful fan – shaped espalier with your ‘Juliet’ cherry shrub and your tree looks indeed wonderfully healthy. Now there are a few things to consider when growing a cultivar of the romance series dwarf sour cherries as is your ‘Juliet’ shrub when the tree is not flowering and fruiting.

Bob Bors and Sara Williams in their book ‘Growing Fruit in Northern Gardens’ state that “Bush cherries often start producing fruit in their fourth and fifth year when they are 1.2m (4ft) tall.” So, your tree may not quite be ready yet for flowering.

Although some varieties seem to have spurs, the most fruit bearing on sour cherries, Prunus cerasus, occurs on one year old wood. By pruning back the side branches of your fan to two leaves you quite likely pruned off quite a bit of the one year old wood where most of the fruit bearing would have occurred. Even if your tree will begin flowering in one or two years, this may be another reason why down the road it will not flower and bear fruit as expected.

When pruning, no more than 20-25% of branches should be removed. If more is pruned, the tree will put its energy into canopy not fruit production.

Please also note that the experts at University of Saskatchewan where the dwarf sour cherries of the romance series were bred emphasize that although these cultivars can be grown as small trees with a single stem they are actually multi stemmed shrubs, and for best results in regards to fruit bearing and easy rejuvenation pruning are grown as such. See Zone 2 hardy Sour Cherries resource of the University of Saskatchewan

That said it is always fun to experiment and you have already put a lot of work into training your tree as a fan that you should not give up on it. Besides giving your tree a bit more time, try to alter your pruning regime to allow for more one year old wood to stay on the tree. A detailed description of the pruning process for a sour cherry fan with illustrations can be found in the book ‘Pruning and Training – What when and how to prune’ by Christopher Brickell and David Joyce, DK 2017. The book is available at the Winnipeg Public Library

References used:

Growing Fruit Northern Gardens, Bob Bors and Sara Williams
Pruning and Training, What, when, and how to prune, Christopher Brickell and David Joyce
https://research-groups.usask.ca/fruit/Fruit%20crops/sour-cherries.php
https://www.canr.msu.edu/uploads/files/2010_NW_orchard_show/Bors_BreedTrainDwarfTarts.pdf

Breeding and Training Dwarf Sour Cherries by Bob Bors. PP Presentation most likely 2010 or shortly after. Comments on pruning – see screenshots below.

https://orchardpeople.com/dwarf-cherry-tree-cherry-shrub/
Episode 7 Interview with Bob Bors

Question: Identifying bronze birch borer

We planted this Parkland Pillar birch one year ago and are wondering if it has bronze birch borer.

Answer:

The Parkland Pillar birch stem is much infected with Bronze birch borer. It is susceptible if it is stressed and the last two years have been stressful. In local nurseries that grow these trees for the nursery trade have found a few tops of trees die back due to drought but most of the trees have revived with the good moisture this year. High levels of borers have not been seen but it could be a real problem. It is too bad when such a distinctive tree has failings. The recommendation would still be to give it another try with better watering and mulch.

It is possible that insufficient watering was done and that there is a pocket of borers in that area. Birch are short lived trees in a dry site. We need to use with care and chose our sites well. Mulching is also a help.

Question: Hardiness of Calgary boxwood shrubs and lacecap hydrangeas

I have some Calgary boxwood shrubs that survived the winter outdoors last year, but sustained some winter kill. I will bring them in for the winter this year. What are the best light, temperature and watering conditions for overwintering these shrubs?

Are any lacecap hydrangeas (similar to Hydrangea macrophylla ‘Lanarth White’) Zone 3 or 4 hardy?

Answer:

Calgary boxwood is hardy to Zone 3. Nevertheless, the Red River Valley’s prevailing west-northwest winds in winter often result in winterkill (desiccation) of boxwood’s evergreen leaves. Two other challenges for boxwood plants in our harsh climate is that full winter sun reflecting off snow causes boxwood to suffer winter burn. If the shrub is covered with snow during the winter, then it is protected from winter burn. However, if a freeze-thaw cycle with wildly fluctuating temperatures occurs in late winter which results in snow melting (exposing the leaves) but the ground is still frozen, there is a risk of severe winter burn occurring.

If the boxwood is located in an area that receives good snow cover, one option is to ensure that it goes into the winter well-watered. Spray the leaves of the boxwood with an anti-desiccant spray such as Wilt-Pruf.

Endless Summer ‘Twist and Shout’ Hydrangea macrophylla is a lacecap hydrangea that is hardy to Zone 4. Local gardeners are having more success, however, with Hydrangea serrata ‘Tuff Stuff’, a mountain hydrangea that is classified as hardy to Zone 5. Interestingly, H. serrata has better cold hardiness than H. macrophylla. There are four cultivars in the Tuff Stuff series.

Question:  Pruning mock orange shrubs

I planted a mock orange last year. This year I was working mostly out of town so not home much. I only got 1 flower, looked half dead.. thought perhaps it partly drowned from all the rain.. Should I prune off dead branches now or how should I overwinter? Its has fence protection on one side.

Answer:

Mock orange shrubs are spring-blooming shrubs and pruning is recommended after the shrub blooms. But in your situation of not having many flowers the suggestion would be to prune it in early spring trimming out any dead branches to the ground. For the other living branches prune them approximately half down to a leaf node. Prune the branch at the leaf node with your pruners angled to the outside of the shrub. Mock orange shrubs are very forgiving when pruned and yours should grow back fully in a year or two. Another suggestion is to remove any plant competition from around the shrub, ie. weeds and grass.

Question: Protecting a hybrid tea rose

Well, winter came as a fast surprise. My rose bushes, a hybrid tea and a ‘Never Alone’, are not covered yet. I was planning on putting leaves on them and covering them with a styrofoam cone but now I can’t get access to the leaves. What else can I use to cover them before putting the cone on them?

Answer:

The ‘Never Alone’,  rose, a Canadian bred and hardy rose to Zone 2b, would be hardy to our climate but not the hybrid tea rose. Most gardeners treat hybrid tea roses as annuals and if they survive the winter it is a joy. The recommendation would be to remove the snow covering and pour some dry potting soil over the rose bushes to form a ‘cone’ over the base of the roses. By doing so, this protects the tender area that would freeze due to cold temperatures. The soil acts as an insulator, and along with the styrofoam cone, you will have a double insulating factor. As a hint, be proactive next fall and gather leaves in the first leaf fall and save them in a large bag so they, and you, will be prepared for any early weather surprises. Here is one of our How-to Videos on winterizing tender roses:  Click here

Question: Aphid infestaion on lilacs

There is a lilac bush in my neighbor’s yard, adjacent to our yard with pests, and certainly under stress. I am looking for some information on how to control this, and or/what to do? Can you point us in the right direction? We live in Stonewall, Manitoba. Below are a few pictures of some of the lilac bush. The stem also has white bumps on it. There are other nearby bushes that seem fine (about five to six feet away).

 

Answer:

This is a severe aphid infestation. The recommendation would be to spray with a water hose on high pressure, as much as the shrub will withstand. As the photos show the majority of the insects are congregating on the new growth ends so concentrate on spraying strongly there. The entire shrub requires a constant water spray, being sure to spray underneath the leaves too, a few times a week until they are under control.

The lilac also has thrips. The water treatment as described will take care of that too. These pests will not disappear quickly but with a constant strong water spray frequently applied they should disappear.

Question: Recommendations for compact deciduous trees for small yards

I’m looking for recommendations on a type of low-maintenance deciduous tree to plant in my backyard. Its purpose is a privacy screen in a smaller city lot, so I’d prefer a mature height of 10 feet or more with spread of seven feet or less. It will be in a south-facing location with full sun.

I’ve ruled out poplars and aspens due to suckering. I’ve looked at pinnacle white birch, but I understand those require significant water and many were damaged by this past 2020/21 winter. Currently, I’m considering columnar flowering crabs or Sutherland Caragana. However, during my research I’ve noted the first is susceptible to fireblight and the latter may have issues with splitting.

Would your master gardeners be able to make a suitable recommendation for my yard?

Answer:

There are very few deciduous tree varieties that have a width as narrow as seven feet (two metres). The first tree that comes to mind is Nannyberry tree form, a native species (Viburnum lentago) which is hardy to Zone 2 and has a mature width of nine feet. It is a beautiful specimen with spring flowers (white) and clusters of dark purple berries on bright red stems in the fall. Birds love Nannyberry.

Two tree varieties with a narrow width of seven feet (two metres) are: ‘Green Wall Crabapple’, quite a cool looking tree, which was developed by Wilbert Ronald, and ‘Midnite Spire’ Rosybloom Crabapple, which is a new introduction by Jeffries Nurseries. Both of these varieties would also be suitable for privacy hedges and screening as they have a similar narrow form with low branches.

A few other compact tree varieties with a width of three metres that you may want to consider are: ‘Goldspur’ Amur Cherry, ‘Muckle’ Plum, and ‘Princess Kay’ Plum.

Question: Can small trees and shrubs grow in raised planters?

We have built raised garden planters. They are made of cedar and are 30 inches tall by 48 inches square. We have found that we have too many to suit our vegetable growing needs. Is it possible to plant shrubs or a small ornamental tree in a few of these planters? Will they survive our Winnipeg climate? If they can survive, do you have any recommendations for type that would tolerate these conditions. I understand that this would be an experiment. Any guidance you can provide would be greatly appreciated.

Answer:

Small shrubs and small trees can be grown successfully year-round in thick-walled raised beds constructed with the type of stone used in retaining walls. But if the thickness of the cedar-constructed raised bed is no more than 3/4 inches, there’s not likely to be adequate winter protection for the root ball of a small shrub or, for example, a small hydrangea tree form with a mature height of just 6 to 7 feet. But especially in the case of a small tree with a mature height of, say, 15 to 20 feet, a modest-sized raised bed would not be enough for the tree’s eventual root system which extends several metres from the trunk. Depending on the location of the raised beds — wind exposure, proximity to a foundation or in a protected area — you might want to experiment with perennials and then when late fall approaches, mulch with straw on the surface of the soil and provide some extra insulation to the roots of perennials by placing styrofoam or straw bales against the outer walls of the raised bed. A neighbour of mine went to this effort each year just before winter and was able to grow Chicago Peace roses successfully in a cedar raised bed for many years.

Question: Can yard plants recover from defoliage from elm-tree worms?

I live in Fort Richmond in Winnipeg and there have been manyworms and webs in our yard this year mainly from elm trees behind our house. Some of the plants are looking pretty ugly. Do you know if they will recover when the worms are finished?

Answer:

Yes, plants are very resilient, and they should recover. But of course it depends how much the leaves have been eaten. As plants require leaves for photosynthesis, which feeds the plants, they would require some parts of the leaves remaining. The suggestion would be to remove the worms on the plants as much as possible so that the plant can recoup quickly.

Question: Pruning tips to espalier apple trees

I’m on a tiny post-war lot near Neil Campbell Elementary School in Winnipeg. I have one area with full sun along a wall that seems ideal for espalier apples. This is my third attempt in four years and I’m afraid to prune for fear of wrecking another tree.  I have not purchased whips. Previously I bought two- and three-year-old dwarf trees in pots from local Winnipeg garden centres. I’ve never seen whips for sale before. Perhaps this is a special order? Glad I’ve found this association.

Answer:

Thank you for reaching out to the Manitoba Master Gardeners with your question. You are writing that it is your third attempt in four years to espalier an apple tree and you assume it was your pruning that the first two trees did not survive. A basic rule when pruning trees and shrubs is to never remove more than 25 per cent of the canopy or branches as enough photosynthesizing leaves are needed to provide the tree with energy to build and sustain its root system and to put out new growth and eventually fruit. So when you train a young apple tree to its horizontal supports keep this in mind. If you are not sure if a branch should be shortened or removed it is better to leave it as you can always go back and prune it in a second step when needed.

In early spring, at the end of March or beginning of April, cut back the central leader to above 45cm (18″) of the lower branches, and leave three good buds to form the new central leader and next level of horizontal branches.
If there are additional lateral branches growing from the main stem cut those back to three buds. (I have read the recommendation to shorten the horizontal arms by about a third to a downward facing bud but did not do this because the horizontals did not seem very long and I did not want to compromise the tree by removing more of the branches). Keep doing the above steps until the tree has reached its last horizontal support.

Next is the summer pruning to keep the tree in its espalier form: I do this just once in early July because the tree I grow, a Norkent apple, does not put enough new growth out to warrant a second pruning six weeks before our average first frost date between September 16th and 22nd. If pruned later than six weeks before the average first frost date, the new branches don’t have the time to harden off to survive our winter. Cut back only new shoots on the horizontal branches and the stem that are more than 20 cm (8”) long. Cut those back to three leaves above the basal cluster of leaves. It is important not to remove new growth that is less than 20 cm (8”) long as these short branches usually end in a fruiting bud or are fruiting spurs.

There may also be some long very vigorous and upright new growth on the horizontal branches; these can be cut off completely. Once the tree has filled its space cut back the new growth of the central leader and horizontal branches.

When you train the branches to the horizontal you may have to do this in two steps to prevent them from breaking: first bend the branches to only a 45 degree angle to the main stem with the help of a bamboo stick tied to the wire support and then in a second step at the end of the growing season lower them to their horizontal support.

Below are two links: one with general information pertaining to our climate about growing apple trees from the University of Saskatchewan; and the other about espalier, which may be of interest to you.

https://gardening.usask.ca/gardening-advice/gardenline-nested-pages/food-plant-pages/fruit/apples.php#Apples
How to Espalier an Apple Tree

Neither have I started my espalier tree from a whip but from a young tree for the same reason as you. The tree had a fairly flat crown and was slowly trained on to its support structure. It is a somewhat unusual way to start an espalier, which, as you correctly observe, is usually recommended to be done from a whip, but if you are not set on trying to create the perfectly espaliered apple tree it does still work.

I attach a few pictures to illustrate an example of the process and the end result. Image 1 shows the tree with just the first horizontal trained. That same summer the branches for the second and third horizontals were chosen and tied to the support structure. The following spring the leader and additional side branches were cut back as described and the training of the last horizontal was started. In the photo from this spring (Image 2) with the tree just leafing out you can see that the second and third horizontal don’t come off perfectly from the main stem, but once the leaves develop this becomes barely visible (Image 3, the tree how it looks today with the summer pruning done about two weeks ago). When you start espaliering a dwarf tree which is preferable, especially if space is an issue, your first horizontals would be trained quite a bit lower than what you see in these photos.

If you would like to start training an espalier from a whip I recommend you contact your preferred garden centre soon to inquire if they take such orders and when it would be the best time to place it.

Question: What types of insect rolls leaves on trees?

The small tree is now growing the third set of leaves. It lost all its leaves in the spring. They are rolled together and a larvae or insect is inside in a net similar to a spider net. This year, the big tree was affected in the spot close to the other tree. I sprayed twice within two weeks. I’m not sure if that helped or if the insects just left.

 

 

 

 


Answer:

From what is seen from the photographs, one tree appears to be a Basswood and the other a Manitoba Maple. Since the tree has not been seen in situ in person, it is difficult in diagnosing the problem. It is critical to identify both the tree species and the insect or disease affecting it before taking action to remedy the situation.
It is suggested the rolled leaves are the result of leafrollers. Leafrollers are common in Manitoba. Archips purpurana attacks basswoods, birches, aspens, and willows.

Moth larvae form feeding shelters by spinning silk webs around young leaves and rolling them together. Single leaves may also be rolled into tight cylinders. The larvae may skeletonize the leaves, leaving only the veins in tact, or consume the leaves whole. Severed leaf segments remain within the silk webbing and become bleached or brown.

When disturbed, the larvae become agitated and wiggle vigorously. They often fall to the ground or dangle from silk strands. The one-inch long worm-like larvae is light green with a dark brown head. Leafroller damage does not usually have an adverse effect on a tree’s vigour, as foliage loss is relatively low. But, aesthetic value is reduced by leaf disfigurement. To eliminate unsightly appearances, rolled leaves can be removed and heavily infested areas can be pruned.

Insecticides are often ineffective, because the larvae are protected within the rolled leaves and direct contact is inhibited. In future situations, biological insecticides such as Btk are effective when the larvae are exposed. As a guideline to treating any apparent infestation or disease, a diagnosis is critical before treating any problem. As with humans, treatment of trees without diagnosis is malpractice. It is important to know exactly what the problem is before applying any treatment.

A dormant oil application before bud break can effectively destroy over-wintered egg masses. Dormant oil is not recommended for maple trees.

Question: Causes of shrivelled leaves on crab apples

 

 

 

 

 

We recently purchased a cottage in the Gimli area in Manitoba and believe the tree in the photo above may be a type of apple tree. One of the branches has nice leaves and had some flowers; however, the other branches start to get leaves and then they appear to shrivel up right away before they reach full size. The first photo is the leaves looking like they may be okay and the second photo shows how they turned brown and shrivelled up. Can you please offer any advice of what I can do to save this tree?

Answer:

There are two diseases that may be possibilities in your case. One is fire blight. Erwinia amylovora is very difficult to control. The disease develops rapidly in early spring during rainy, cool weather when temperatures are around 15 degrees Celsius and trees are typically starting to bloom. Blossoms and young leafy twigs show the first signs — appearing wilted or shrivelled and eventually turning brown to black. The tips of infected young twigs wilt and die, forming a shepherd’s crook as the disease moves down the branch. Dead leaves often remain attached to the branch. A milky-like sticky liquid carrying the bacteria can often be seen on the stems and branches.

Fire blight is difficult to control. You can try this: remove all infection sources such as blighted twigs and cankers. Pruning should be made 12 to 18 inches below infected tissue. Disinfect all tools between cuts. Avoid high nitrogen fertilizers. Chemical control is difficult, requiring a daily regimen, often with unsuccessful results. Typical chemical recommendations for fire blight on apple trees is streptomycin or copper fungicide during bloom time. The prognosis is not good.

The second possibility is the fungus, Venturia inaequalis, known as apple scab. The disease causes serious leaf drop on susceptible crab apple trees. Periods of rain and cool temperatures, as we had this spring, provide conditions for apple scab to develop. Infected leaves on the ground from the previous year are the source of the fungal spores that can infect the crab apple the following spring. Spores from old leaves are carried on air currents to developing leaves. This primary infection produces olive-coloured spots on leaves. As the fungus multiplies on the leaves, new spores are produced, starting a secondary infection. Infected leaves become curled and yellowish with lesions, eventually turning brown. The disease causes premature leaf drop. It is too early for fruit, but infected fruit will have raised scab-like lesions and typically will fall to the ground.

Crab apple varieties vary greatly in their susceptibility to apple scab. Susceptible trees are often bare by August, making it difficult for the tree to store energy for future growth. A weak tree will find it difficult to overcome environmental stresses. Trees with apple scab often survive and will re-leaf the following spring. It can occur to a tree every year. If it is apple scab, you can choose to do nothing other than disposing of all dropped leaves. Or, you could apply a fungicide as a preventative treatment with a spray program that begins at the first sign of leaf emergence in the spring. But, you will need to determine first whether this tree does, in fact, have Venturai inaequalis.

There are steps to follow in the spring to help to protect the tree from Venturai inaequalis. Prune the trees in early spring (late March) to ensure good air circulation. It does not look like your tree has an issue with air circulation. Good circulation will ensure that the leaves do not stay wet after rain or dew. It does not look like this tree is being shaded or crowded by other trees, but if it is, try to give it as much space as possible. All crab apple trees need good air circulation and access to sunlight. Make sure sprinklers do not wet the bark or leaves of the crab apple tree. This will help to deter the disease. Sanitation is key. Rake up and dispose of leaves that have dropped around the tree. If trees in the neighbourhood have the disease, spores can blow in from elsewhere, but ensure you are doing what you can to keep the area clean. You could choose to remove this tree and in its place plant a crab apple that is a resistant variety to apple scab.

A third possibility would be Cedar-apple rust, but there would have to be a cedar tree growing in the vicinity.

If these suggestions do not appear to be consistent with what you are seeing, it will be necessary to have someone look at a branch from the tree for analysis. It would be recommended doing that regardless, as it is the only way to identify definitively the nature of the problem with your crab apple tree.

Question: Pruning a cracked branch on a mature Amur maple

I have a lovely, large, many-branched Amur maple in my back yard. One large branch has developed a crack coming from the Y joint almost all the way to the base. We are thinking of cutting it off at the joint and hoping the tree will heal itself. Any advice would be welcomed.

Answer:
It is always very sad when we have a mature tree, that we enjoy in our yards, and it is showing signs of aging. This is a severe crack and the recommendation would be to call in a qualified arborist to come on site and access the issue. If the branch can be removed, they would do so properly.

Question: How to care for and fertilize hydrangeas


I visited Colleen Zacharias’s garden on a tour, and she said she uses Gaia Green fertilizer. I bought some but I would like to ask her to recommend how and when to use it. Maybe she could talk about it in the context of fertilization in general.

 

Answer:

Hydrangeas are heavy feeders and are also moisture-loving plants. To feed my hydrangeas, I add a two-inch layer of compost every spring around each shrub, taking care to not place the compost next to any of the stem growth. In mid-summer, to help conserve moisture, I add a two-inch layer of shredded leaves to the soil surface layer around my shrubs, which, through the decomposition process over time, also contributes nutrition. When my hydrangeas begin blooming, I add a small amount of Gaia Green Power Bloom, which is an organic high phosphate fertilizer “specifically formulated to support prolific flowering”. (I want to believe this but at the same time, I would not use Gaia Green in place of compost).

Gaia Green Power Bloom includes the following: bone meal, mineralized phosphate, fishbone meal, rock phosphate, mined potassium sulphate, glacial rock dust, insect frass, feather meal, basalt rock dust, kelp meal, humic acid, gypsum, greensand, blood meal. Some information about Gaia Green that I included in my column some years ago: Glacial rock dust is a natural mineral product that aids in improving soil structure. It is a good source of calcium, iron, magnesium and potassium. Fish bone meal is high in phosphorus and promotes rooting and flower development. Bat guano is also a good source of natural phosphorus. It is used in annual containers to promote bloom production and enhances yield and flavour in vegetables.

The directions say to broadcast and incorporate up to 1.4 kg per 10 square feet. I don’t use nearly this amount.
One thing about Gaia Green is that it is very fine — a dustlike texture. It is important to apply it on a calm day, early in the morning, and to water deeply following application.

Years ago I talked to Michael Dean, the founder of Gaia Green, for my column:
Michael Dean is the creator of Gaia Green Organic Fertilizers. Started in 1990 in Grand Forks, B.C., Gaia Green is sold across Canada. Dean is a passionate advocate for shifting the emphasis from fertilizing plants to one of feeding and remineralizing the soil.

“There are over 75,000 different species of beneficial bacteria,” Dean says, “and 25,000 to 30,000 species of beneficial fungi that live naturally in symbiosis in our soils and these organisms convert nutrients.” Each of these beneficial organisms have different roles in breaking down nutrients. Some, says Dean, digest minerals such as manganese, boron and selenium, and when they are provided with their food source, their population explodes.
Dean includes a wide variety of ingredients in his blended products to activate as many of these species of bacteria and fungi as possible and convert these natural nutrients into plant available forms. By activating the soil food web, the resulting healthy soil ecosystem, says Dean, has a profound effect on plant vitality, allowing it to function at its highest potential. “Healthy plants are more naturally resistant to disease and pest infestation and have greater drought tolerance,” he adds.

Dean eschews the conventional methodology that says chemical fertilizers consisting mainly of nitrogen, phosphorus and potassium (NPK) are the best approach. “Chemical fertilizers are in ionic form, and they are totally soluble. A third of it washes away into the ground water, creating environmental pollutants, and another third volatizes into the air in hot weather, actually evaporating.”

Question: Fall protection for hardy roses

I have hardy roses I bought from the garden center this summer. Several of them are 24 inches high and a climbing rose that has grown to reach the roof of my pergola. So how do I prune and protect the 24-inches high one and the climbing one this winter? Here are the names:
Shrub rose – ‘Thérèse Bugnet’
Hardy Rose – Pink Grootendorst
Hardy rose – ‘Alexander Mackenzie’
Climbing Rose – ‘John Cabot’

Answer:

The short ones, providing that they are either the Parkland (from Morden) or the Explorer (from Ottawa) series, or even the Artist Series (Bill Reid, Emily Carr, etc. or the 49th Parallel Series (Aurora Borealis, Chinook Sunrise, etc.), the recommendation is that you don’t need to cut them down, or do anything at all to them; they are hardy in our Zone 3 climate. If the climbing one is William Baffin (an Explorer), you wouldn’t need to cut it back either, other than to tidy it up. My William Baffin got chewed up by rabbits over the winter, but it came back gangbuster this spring, and is now around seven feet tall. I just leave it alone and let it do its own thing. If, however, it is not one of the above series, then I would be more careful with winterizing it.

Thérèse Bugnet is a hardy rose bred here in Canada, Alexander Mackenzie is of the Explorer series, as is John Cabot, while the Grootendorst roses are rugosa roses, and are very hardy as well.

Therefore, I would say don’t bother cutting these roses back, other than John Cabot, which grows fairly tall, and I would suspect that is the one that was labelled as a climbing rose. If it is taller than four feet right now, you could cut it back to two feet, but it’s not essential. Do not worry about winter either. You purchased a nice selection of hardy roses. They should do very well for you next summer.


Question: Encouraging fruit producution on Jostaberry bushes

I had the question about Jostaberry bushes on the CBC radio this morning. The bushes are about three years old with no fruit produced yet. They are running wild. See attached photo. What fall treatment do they need? Pruning? I live just outside of Winnipeg.

Answer:

I was very interested in your question and did research your Jostaberry shrub. It is of the Ribes family to which gooseberries and currants belong. Jostaberry is a cross between black currants and gooseberries. The shrubs are very disease resistant and self-fertile (meaning one needs only one plant to bear fruit) but have slow fruit set. Birds love the fruit and it is recommended that the shrub be covered with a row cover to protect the produce.

Pruning would be done in late winter or early spring but can also be done in autumn once the leaves fall. Unless the branches are diseased or damaged do not shorten or cut back the canes (branches), as the spurs which produce the fruit, would be unknowingly removed. Most of the fruit for Jostaberries are born on two- and three-year old canes. The goal to pruning Jostaberry is to keep three or four strong new canes per year, and to remove an equal number of old canes per year. In this system, mature plants have 9 to 12 canes after pruning and three to four each of one-to-two and three-year old wood. Remove all wood that is four years old or older. When removing the canes, cut them as close to the ground as possible. And remove any canes that are drooping and close to the ground.

Question: What causes “cupping” on lilac leaves?


I noticed a while back that the leaves on one of my lilac bushes were all cupped up. Yesterday, I noticed that another bush also has some leaves that are cupping. I did give them some Miracle Grow in the spring, would this do it? Or do I have some kind of disease in them? I have several bushes in my yard and am scared I will loose them all.

 

 

Answer:

The cause of your lilac leaves cupping in this manner would be caused by a herbicide being sprayed in close proximity to your shrubs. If the Miracle Grow was a very strong concentration, more so than the directions given on the package, it too can affect the lilac. But the general consensus would be a herbicide, ie. Killex, or something similar. If it was applied on a windy day, the spray can easily be blown to affect a wider area.

Question:  What causes leaf drop-off on established roses?

I have three ‘Winnipeg Parks’ roses amongst my plantings in the front of the house in an eastern exposure. Two of the plants are older (plus-six-years and two-years). The blooms are many, beautifully formed, no problem. In the last one-and-a-half weeks, I have noticed leaves dying, and this morning, many on each plant are dead. I have dusted with Rose dust – not for any reason other than I thought it may be bugs, but do not see any. I would usually fertilize this week with Miracle Grow rose food. Can you suggest what procedures I should follow to identify the problem and get these back on track? I used Larter’s Rose & Flower Dust which supposedly is an insecticide and fungicide. As I said, they were looking great until recently … and then?

Answer:

The leaves looking like this is caused by rose sawfly. It is too late for this year but leaves should grow back and the suggestion is to hand-pick off the larva early next spring or blast them off with a water jet. Insecticidal soap also kills them safely. They only produce one lot of larva per season so there shouldn’t be any new damage.

Question:  Suggestions for planting roses near a concrete foundation

I would appreciate if someone could advise me of a small rose bush perennial that would get morning sun (east) against our concrete foundation. I have had no luck previously with black spots, aphids, etc. killing my rose bushes. I see there is a Parkland and Canadian Explorer series that are improved to deal with these problems. I live in a private condo home and residents drive by this area of my home on entering our condo village. I would like a small one due to winds and condo restrictions of 36-40 inches and other plantings restricting width so 24-36 H & the same wide is what I am searching for.

Also I have had ant problems for which I have used Ant Out recommended by a St Mary’s garden shop and also homemade cornstarch and icing sugar which never got to the queen ant. Any suggestions would be appreciated.

Answer:

Roses need some sun to flower well. They will manage with less, just flower less. Overall, roses are difficult to grow well here. They may just survive and not really do a lot. Also, foundations often don’t get much rain. It is likely alkali near your foundation and roses don’t really mind that. It is worth a try but this is not the best position for a rose.

Roses do best in an open, full-sun position in a bed that only has roses in it. They don’t like competition. Heavy clay is fine for them as they like to be fed well and stay a bit moist. Your conditions are not ideal but may be adequate.
There are as you suggest the Parkland and Canadian Explorer series of roses. Most of the Morden roses such as ‘Morden Blush’, ‘Morden Ruby’, and ‘Morden Fireglow’ are small as is ‘Winnipeg Parks’. The Canadian Explorer series tend to be larger but ‘Henry Hudson’ and ‘Simon Fraser’ are small. There is a newer series of hardy for Zone 3 roses called the Artist Series: ‘Oscar Peterson’, ‘Campfire’, ‘Emily Carr’, ‘Bill Reid’, and ‘Felix Leclerc’. You haven’t mentioned what colour you want. Many roses are partially frozen in our winters but if these are bought on their own roots (not grafts) then even if they are frozen down to the ground the same rose will come back. It is often hard to grow a rose to its full potential so some of the bigger ones may never get to that size.

There is quite a variety of these hardy roses in the box stores garden centres in Winnipeg and without naming names some for as little as $10 each. The recommendation is to go on the internet and decide which colour and style you like then make a list and go around looking for it.

Aphids should be washed off with a hose jet and will likely be eaten by the new aggressive ladybugs. When choosing a rose, look for disease resistance; then you will have less trouble with black spot. Put some bone meal to encourage root development into the hole you dig and water regularly in the first year or two to help the rose establish. After winter when your rose has leafed out, prune out the dead wood but be patient as some of the apparently dead branches will recover. It is unusual to have a problem with size as it is hard for even hardy roses to survive in our climate but if a rose grows too big then you can always prune it.

If the standard ant bait hasn’t worked for you , you could try Ant Nematodes which are little worms that infect and kill ant larvae. It is important that you get them before the use-by date as fresh as possible and buying on-line seems to be cheaper and more available than in the local garden centres, many of which haven’t heard of this biological control.

Question: Can hybrid tea roses survive the Zone 3 winter?

For the last couple of years my rose bush, a ‘Chicago Peace’, has grown very well – tall, shiny green leaves – but it has not produced any buds or roses. I have fertilized it first thing in the spring ( with a rose fertilizer) and then watered it during the summer. It gets full sun all day. I would appreciate any suggestions you could give me so that I can have the best chance of having it bloom next season.

Answer:
I presume you live in Manitoba and so in our climate it is often very difficult to get a hybrid tea rose to survive the winter. Most hybrid tea roses are grafted on a hardy root-stock (unless they are bought as specifically grown on own roots) . Often the freezing of winter will kill the graft but not the hardier root-stock which will then often grow vigorously next spring but unfortunately is unlikely to flower and if it does it will not be the beautiful ‘Chicago Peace’. In general, you are doing all you can to encourage flowers, most importantly growing in full sun, fertilizing, and watering appropriately so I am sure your bush is in good condition but I suspect it is no longer ‘Chicago Peace’. Hardy roses for our climate are lovely but not as gorgeous as the big hybrid teas. Some winters, a hybrid tea may over-winter very well depending on the winter experienced. One can tell the difference between the rootstock and the grafted rose by the number of leaflets on each compound leaf. There should be five or less on the hybrid tea and seven or more on the root-stock.

Question: What caused shrubs not to shed their brown leaves in fall?

Ordinarily, my bushes shed their leaves in the fall. This last fall (2017-18), they just turned brown and remained on the bushes and trees. Odd?

Answer:

The reason is that we had quick and early cold winter temperatures and, up until that time, it was fairly mild. Normally, there is a slow degradation of temperatures, and trees adjust to this and prepare themselves for winter dropping their leaves so as not to lose too much moisture through them. When trees are preparing for winter, the connection between the leaf stems and the branch, the abscission layer, produces an enzyme that facilitates the falling of the leaves. With our sudden cold temperatures this did not occur and, hence, your trees and bushes still have their dried brown leaves on them. Come spring, they should be ‘pushed’ off the twigs when the new leaves begin growing.