I was probably overly harsh on the subject of Japanese maples and mycorrhiza on Friday. In practice, some benefit can be obtained from mycorrhizal treatment but overall, the difference in growth is going to be marginal, assuming that you have a healthy plant to start with. What mycorrhiza can't do is revive or improve the health of a poorly performing maple. As far as the soil microflora is concerned, boosting bacteria numbers and variety will have a far more impressive effect on the overall well-being of your Japanese maple and this is a subject I'll go into in more detail in a future post.
The reason mycorrhiza have little effect on maples is due to how they originally evolved and the types of plant they developed a symbiotic relationship with. Although it's not immediately apparent, the fine feeding roots of a Japanese maple are covered with a mass of root hairs. If you grow a seed and the initial root hits a small air pocket in the growing medium, the root hairs are easily visible. Under normal growing conditions, if you pull up a maple you won't see anything as the root hairs will be within the soil or are easily pulled off. You can see a more obvious picture of root hairs on something such as a lily bulb, particularly the roots that grow above the bulb from the base of the stem.
Root hairs serve the same purpose as mycorrhiza and specifically arbuscular mycorrhizae, as these are the symbiotic fungi most closely associated with garden plants. The root hairs penetrate the soil and provide the plant with it's nutrients in the same way as mycorrhiza do and no symbiotic relationship is required for the plant to perform 100%.
The root hairs also serve another purpose and that is as a barrier to fungi, good or bad and inoculating the soil will mean the fungal hyphae can't reach the roots and develop within them. This barrier to mycorrhiza is only present in plant species that are relatively 'new' and have developed more sophisticated forms of nutrient uptake. Acer palmatum is a very 'young' species in terms of evolution and is still unstable. This manifests itself in it's inability to produce offspring that look identical to the parent; sow a thousand seeds and you will have the majority of them unique in leaf shape and form. They may all look very similar, either red or green, but there will be subtle differences in shade of colour, the serration on the lobes or leaf size.
Where mycorrhiza can make an appreciable difference, however, is with the more 'primitive plants and I shall, hopefully, cover that tomorrow, as this type of plant is the reason for the existence of mycorrhizae.
Showing posts with label Gardening. Show all posts
Showing posts with label Gardening. Show all posts
Wednesday, November 7, 2007
Tuesday, November 6, 2007
Mycorrhiza, nature's root extensions
Looking through all the information I have on mycorrhiza, to put in this post or spread it over several days would produce an impossibly long article. For the moment, the best introduction I can give is to send you to the following site: Introduction to Mycorrhizas
I'll discuss how best to manage mycorrhiza in the garden tomorrow and provide some information for growers of exhibition vegetables.
I'll discuss how best to manage mycorrhiza in the garden tomorrow and provide some information for growers of exhibition vegetables.
Thursday, November 1, 2007
Japanese maple pests
Today I took my first inspection through my stock plants to see what wood is going to be available for grafting this winter and was glad I hadn't left it any longer. Although I regularly inspect plants during the summer when aphid populations can build up quite quickly, some had obviously been overlooked. Several trees had infestations of juvenile aphids crawling all over them and action need to be taken fast.
To the casual observer, the sight of aphids in the autumn, whilst acting as a reminder that they need to be removed, won't engender any sense of urgency. It's a job that can be done when you've got some spare time next week or next month, if at all. You're thinking 'the only thing they seem to be doing is putting a sticky deposit on the leaves; they're going to fall off shortly and the upcoming cold weather will kill the aphids off so I'll leave it as I've got more important things to do in the garden'. Big Mistake!
What you can't see unless you get up very close and if you can see, it's too late, is the aphids are laying eggs. Initially, they're walking up and down leaf stalks and shoots, but gradually they will start congregating in specific ares, ready to unleash a time-bomb next spring. They will start laying their eggs in the leaf axils where next year's buds are developing. They're going to be in tiny cracks in the bark next to the buds and in the bud sheaths themselves. Once they've been laid, there is nothing you can do apart from wait for them to hatch next spring.
Unfortunately, next spring is going to be too late to minimise the extensive damage they can cause as, conveniently for them, they hatch just as the buds start expanding. But this time they're not going to be walking all over the leaf surface, at least not initially; they're going to be within the expanding buds. But it gets worse! They're not interested in the fully opened leaves where it's easy to get at them; they're going to be feasting om the most succulent part of the shoot, the growing tip and all you'll see is a mass of sticky distorted shoot tips covering the whole of your Japanese maple and severely weakening the growth of your plant.
When it gets to this stage, control is very difficult without causing extensive damage to the shoots. Repeated applications, because they won't go without putting up a fight, with garden chemicals can do almost as much damage as the aphids themselves. By spraying now with something like a soap solution or Neem oil, that works by suffocating them, you can quickly eliminate future problems. So today's tip is check for aphids, not just on your Japanese maples, but on all your trees and shrubs. That way you won't have any unpleasant surprises next spring!
Need more information? Get it at growing japanese maples.
To the casual observer, the sight of aphids in the autumn, whilst acting as a reminder that they need to be removed, won't engender any sense of urgency. It's a job that can be done when you've got some spare time next week or next month, if at all. You're thinking 'the only thing they seem to be doing is putting a sticky deposit on the leaves; they're going to fall off shortly and the upcoming cold weather will kill the aphids off so I'll leave it as I've got more important things to do in the garden'. Big Mistake!
What you can't see unless you get up very close and if you can see, it's too late, is the aphids are laying eggs. Initially, they're walking up and down leaf stalks and shoots, but gradually they will start congregating in specific ares, ready to unleash a time-bomb next spring. They will start laying their eggs in the leaf axils where next year's buds are developing. They're going to be in tiny cracks in the bark next to the buds and in the bud sheaths themselves. Once they've been laid, there is nothing you can do apart from wait for them to hatch next spring.
Unfortunately, next spring is going to be too late to minimise the extensive damage they can cause as, conveniently for them, they hatch just as the buds start expanding. But this time they're not going to be walking all over the leaf surface, at least not initially; they're going to be within the expanding buds. But it gets worse! They're not interested in the fully opened leaves where it's easy to get at them; they're going to be feasting om the most succulent part of the shoot, the growing tip and all you'll see is a mass of sticky distorted shoot tips covering the whole of your Japanese maple and severely weakening the growth of your plant.
When it gets to this stage, control is very difficult without causing extensive damage to the shoots. Repeated applications, because they won't go without putting up a fight, with garden chemicals can do almost as much damage as the aphids themselves. By spraying now with something like a soap solution or Neem oil, that works by suffocating them, you can quickly eliminate future problems. So today's tip is check for aphids, not just on your Japanese maples, but on all your trees and shrubs. That way you won't have any unpleasant surprises next spring!
Need more information? Get it at growing japanese maples.
Wednesday, October 31, 2007
Suitable soil types for Japanese maples
One of the many comments I get from visitors to my stand when I'm exhibiting at flower shows is 'I cant grow Japanese maples on my soil' and it seems to be a common fallacy that they need an acid soil. The reasoning behind the assumption is they've grown a maple before and it's died and they garden on chalk, lime or clay soils; therefore it's the fault of the soil.
The maple family in general and Japanese maples in particular will tolerate any type of soil and are quite happy with a pH that ranges from 4.5 to 7.5. The lower limit will be when growing in pure peat without any added lime to counteract the acidity, right up to very alkaline soils based on chalk. The common denominator of all so-called problem soils is not the pH but rather their inability to hold moisture during the summer.
The only overriding requirement as far as soil types is concerned is that it is reasonably free-draining. Maples dislike having their roots in waterlogged soils, especially during the winter months when there is no root activity to reduce moisture levels and the root system runs the risk of being suffocated through lack of air movement. The end result of that scenario is the roots will rot and allow infection to spread through the plant.
To combat the problem of specific soil types not holding sufficient moisture in the summer, we come back to the need to mulch. This overcomes the perceived problem of growing Japanese maples in soils that, at first glance, seem inhospitable to their needs.
Waterlogging in winter is often the cause of Japanese maples coming out in leaf in the spring, putting on a good display of foliage and then suddenly dying, often coinciding with strong winds or a slight frost. These events are then blamed for the demise of the plant whereas the real culprit has been waterlogging and moisture stress. The tree still has some reserves of energy left in what remains of the roots and also in the body of the tree, which is why new growth starts out with such promise. Unfortunately, with little or no back-up it can't sustain that growth and the result is sudden death. Mulch to prevent stress in the summer and pick an area in your garden that has reasonable drainage and you remove at a stroke the main reason maples die.
Although frost can cause some damage in early spring just as the leaves are coming out, a healthy plant will continue to put out new growth and damaged leaves will have no long term affect. There is, in fact, an easy way to differentiate between frost damage and root damage. If the tips of the shoots are blackened or burnt but the shoot is still generally firm, it's frost. If the shoots droop and there is no firmness in them at all, then the damage is in the root system and the plant is going to die or is already dead. There are ways to rescue them and Ill cover some methods that could potentially help in a later post, but before your Japanese maple is completely dead!
Need more information? Get it at growing Japanese maples.
The maple family in general and Japanese maples in particular will tolerate any type of soil and are quite happy with a pH that ranges from 4.5 to 7.5. The lower limit will be when growing in pure peat without any added lime to counteract the acidity, right up to very alkaline soils based on chalk. The common denominator of all so-called problem soils is not the pH but rather their inability to hold moisture during the summer.
The only overriding requirement as far as soil types is concerned is that it is reasonably free-draining. Maples dislike having their roots in waterlogged soils, especially during the winter months when there is no root activity to reduce moisture levels and the root system runs the risk of being suffocated through lack of air movement. The end result of that scenario is the roots will rot and allow infection to spread through the plant.
To combat the problem of specific soil types not holding sufficient moisture in the summer, we come back to the need to mulch. This overcomes the perceived problem of growing Japanese maples in soils that, at first glance, seem inhospitable to their needs.
Waterlogging in winter is often the cause of Japanese maples coming out in leaf in the spring, putting on a good display of foliage and then suddenly dying, often coinciding with strong winds or a slight frost. These events are then blamed for the demise of the plant whereas the real culprit has been waterlogging and moisture stress. The tree still has some reserves of energy left in what remains of the roots and also in the body of the tree, which is why new growth starts out with such promise. Unfortunately, with little or no back-up it can't sustain that growth and the result is sudden death. Mulch to prevent stress in the summer and pick an area in your garden that has reasonable drainage and you remove at a stroke the main reason maples die.
Although frost can cause some damage in early spring just as the leaves are coming out, a healthy plant will continue to put out new growth and damaged leaves will have no long term affect. There is, in fact, an easy way to differentiate between frost damage and root damage. If the tips of the shoots are blackened or burnt but the shoot is still generally firm, it's frost. If the shoots droop and there is no firmness in them at all, then the damage is in the root system and the plant is going to die or is already dead. There are ways to rescue them and Ill cover some methods that could potentially help in a later post, but before your Japanese maple is completely dead!
Need more information? Get it at growing Japanese maples.
Tuesday, October 30, 2007
Death by watering Part 2
As promised, here are some photos of Japanese maple seedlings growing in an extremely dry environment. The pictures are quite small so I've put a link to a page on my web site where you can see bigger images; just click on the first picture. The first picture shows a general view of the tunnel that was used to grow understock; you'll notice that all the plants are red maples; the reason being that if the graft fails I still have a atropurpureum seedling to sell as they are always more popular than green forms. Even the experts such as myself(!) are not infallible! These photos were taken in April and the plants have just come into growth. The overhead irrigation lines were dis-connected when the crop, of which these seedlings were part of, was lifted thirty months prior to these pictures being taken.
The second picture shows the seedling in the centre of the tunnel whilst the last picture shows plants near the side of the tunnel. Notice that they are slightly larger due to condensation running down the inside of the film as indicated by the presence of moss next to the film. Also, because they are at the edge of the tunnel, they are the first to get the benefit of any deep moisture that migrates through the soil. The film is buried in a trench fifteen inches deep but moisture will still creep in as nature abhors an imbalance. Shade temperatures in the summer get up to 100 deg.F and the soil in the tunnel would have been bone dry but there would always be a small but constant supply of moisture at about two feet or possibly lower with the tunnel cover acting as a mulch to prevent fluctuations in moisture levels. Even in that environment, if I'd put a sheet of polythene on the ground, the soil would have been damp right up to the surface!
I hope that I've succeeded in showing you that watering a Japanese maple once it's been planted can be a dangerous exercise and that they are better left well alone. As water becomes increasingly scarce and expensive, particularly if your local utility has decided to ration it or impose a hosepipe ban, it is far better to let your maple fend for itself; they're much more intelligent than us when it comes to knowing what it's needs are as they've been doing it for a very long time!
Of course, all the above pre-supposes that you have a healthy plant waiting to be transplanted. The reality is likely to be somewhat different as most purchased plants exhibit some degree of poor health and may well need a period of convalescence before they're ready to go out into the big, wide world. This is another subject in need of a visit and I shall go into it in some detail in the near future.
Need more information? Get it at growing Japanese maples.
Monday, October 29, 2007
Death by watering
First, my apologies. The illustrations of Japanese maples growing without water will have to be postponed until later in the week. The raw pictures need to be processed before they can be uploaded but over the weekend I took advantage of the break in the weather to make a start on seed collection.
When it comes to watering Japanese maples, particularly during late spring and summer, most people will regularly apply water to the soil without understanding the affect this has on the plant. In hot weather most of the water will evaporate very quickly and what's left will moisten only the very top of the soil. The act of watering will also compact the soil and build up a barrier to air and water.
The fine feeding roots are encouraged to move up to the surface in search of moisture but if the surface is allowed to dry out between watering, very likely in hot weather, they can be killed by lack of moisture and heat build-up. Symptoms of so-called leaf scorching can lead to more water being applied to the extent that the surface becomes waterlogged and the feeding roots die through suffocation.
If no water is applied at all, the roots will gradually move down into the soil, following the moisture over the course of the season and a far healthier plant will ensue. There will be periods however, especially during late summer when soil moisture levels are at their lowest, when some leaf scorching can occur. For the reasons stated above, giving your Japanese maple a 'good soaking' is not going to help at all.
The ideal solution, therefore, is to mulch the plant and the best mulch is going to be a sheet of polythene. This can be held down by gravel, pebbles, wood chip or any material that is going to look more attractive than polythene sheeting! The purpose of this exercise is to trap moisture below the barrier and this will be fairly constant, allowing the plant to get all the moisture it needs without being stressed. Natural rainfall won't have any affect on levels under the barrier but will gradually move across through the soil avoiding any peaks.
To give you an example of this method in practice, lift up a paving stone or any other object that's lying on the soil surface and you will notice that the moisture has been trapped under it. Perversely, the hotter the weather, the more moisture is drawn up through the soil as the moisture is heated and rises, corresponding with an increase in the water requirements of your maple.
With this method, your Japanese maple will have an adequate supply of moisture throughout the growing season without the risk of stressing it due to fluctuations in watering.
Need more information? Get it at growing Japanese maples
When it comes to watering Japanese maples, particularly during late spring and summer, most people will regularly apply water to the soil without understanding the affect this has on the plant. In hot weather most of the water will evaporate very quickly and what's left will moisten only the very top of the soil. The act of watering will also compact the soil and build up a barrier to air and water.
The fine feeding roots are encouraged to move up to the surface in search of moisture but if the surface is allowed to dry out between watering, very likely in hot weather, they can be killed by lack of moisture and heat build-up. Symptoms of so-called leaf scorching can lead to more water being applied to the extent that the surface becomes waterlogged and the feeding roots die through suffocation.
If no water is applied at all, the roots will gradually move down into the soil, following the moisture over the course of the season and a far healthier plant will ensue. There will be periods however, especially during late summer when soil moisture levels are at their lowest, when some leaf scorching can occur. For the reasons stated above, giving your Japanese maple a 'good soaking' is not going to help at all.
The ideal solution, therefore, is to mulch the plant and the best mulch is going to be a sheet of polythene. This can be held down by gravel, pebbles, wood chip or any material that is going to look more attractive than polythene sheeting! The purpose of this exercise is to trap moisture below the barrier and this will be fairly constant, allowing the plant to get all the moisture it needs without being stressed. Natural rainfall won't have any affect on levels under the barrier but will gradually move across through the soil avoiding any peaks.
To give you an example of this method in practice, lift up a paving stone or any other object that's lying on the soil surface and you will notice that the moisture has been trapped under it. Perversely, the hotter the weather, the more moisture is drawn up through the soil as the moisture is heated and rises, corresponding with an increase in the water requirements of your maple.
With this method, your Japanese maple will have an adequate supply of moisture throughout the growing season without the risk of stressing it due to fluctuations in watering.
Need more information? Get it at growing Japanese maples
Wednesday, October 24, 2007
Some thoughts on planting Japanese maples
Last week I put in a planting scheme for a customer that I'd dealt with before , about nine years ago. In fact, if you want to see some of the maples I put in originally have a look at this picture, taken a couple of years ago. The main plant in the foreground is Katsura, now about thirteen feet across.
Link
The correct method will be to dig a hole that is only fractionally larger than the rootball and with tapered sides that allows proper firming of the backfill. The less interference with the surrounding soil the better as the microflora that's essential to the well-being of your plant will be damaged when the ground is disturbed.
Making the sides of the hole tapered allows the loose soil to be compacted easily once it's put back which means that the plant is firmly anchored; staking to ahieve the same result should be avoided as it doesn't allow the trunk to flex and therefore build up thickness and strength.
A couple of other tasks that need to be done when planting a Japanese maple will be covered tomorrow and then all that is required is to stand back and admire your handiwork!
Link
The correct method will be to dig a hole that is only fractionally larger than the rootball and with tapered sides that allows proper firming of the backfill. The less interference with the surrounding soil the better as the microflora that's essential to the well-being of your plant will be damaged when the ground is disturbed.
Making the sides of the hole tapered allows the loose soil to be compacted easily once it's put back which means that the plant is firmly anchored; staking to ahieve the same result should be avoided as it doesn't allow the trunk to flex and therefore build up thickness and strength.
A couple of other tasks that need to be done when planting a Japanese maple will be covered tomorrow and then all that is required is to stand back and admire your handiwork!
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