Composting, Gardening, Jorge, Plants

mycorrhizal fungi
A mycorrhizal fungus as viewed under the microscope. Picture credit: Dr. David Midgley (2007) licensed under CC BY-SA 2.5.

Mycorrhizal fungi rootgrow has become a common feature of garden centres of late, and has been advertised as a product that can greatly boost your plant’s health. But does it really work? And when should I apply it?  Before delving into such questions, it would be worthwhile to explain what are mycorrhizas.

What are Mycorrhizae?

The etymology of Mycorrhiza comes from the Greek mykos “fungus” and riza “root”. And this is precisely what mycorrhizae is, a symbiotic relationship between fungi and plants. It occurs in nearly all plant life on land and is thus suspected of being one of the key factors that allowed plants to colonise the land.

The relationship is symbiotic as the fungi and plant provide one another with nutrients that each are maladapted to garner independently. It has its origin in the fact each are different types of organisms, with fungi being heterotrophic and plants autotrophic. Heterotrophs, such as humans, absorb their nutrients from organic sources, but can’t produce energy from inorganic sources. Autotrophs, on the other hand, can produce energy from inorganic sources such as sunlight. Plants do this through the process of photosynthesis that produces carbohydrates. As autotrophs, plants also find it difficult to absorb essential nutrients such as nitrogen and phosphorus.

endomycorrhizae
Mycorrhizal fungi located inside a flax root’s cortical cells as viewed under the microscope.

And this is where the fungi come in. The fungi that can easily absorb such nutrients interacts with the plant’s root system, which the plant willingly allows, providing such nutrients in return for the carbohydrates that itself cannot produce.  It does this through expanding its roots’ surface area that can absorb nutrients and water. They also provide the additional benefit of increasing a plant’s resistance to pathogens, preventing root disease.

As a side-note, the mycorrhizas were once divided into broad groupings, the ecto (outside) and endo (inside) varieties, with the former (usually) coating the root cells and the latter intermeshing into the plant root cells; although today they have been divided into new sub-categories or superseded with new typings. The endo varieties are difficult to spot, while the ecto varieties presence may be hinted at with the appearance of toadstools, or coated, oddly-branched roots.

The Leccinum aurantiacum – an ecto variety of mycorrhizal fungus. Picture Credit: Tomas Čekanavičius (2006)  licensed under CC BY-SA 2.5.

Do I Need to use Mycorrhizal Rootgrow?

It is suspected that neither fungi nor plants could survive in many situations without such a relationship. Mycorrhizas is fairly ubiquitous throughout the soil, and can infect a wide range of plants, so it is highly probable that suitable plants will become infected in their lifetime. There may be some exceptions to this, such as heavily cultivated soil and isolated rocky outcrops, but more on this later.

Scientifically, there is little evidence supporting the use of mycorrhiza rootgrow. The British Standards Institution, which produce technical standards on an array of products, does not recommend using the rootgrow for planting trees as a matter of routine. At Texas A & M University, a team grew plants in soils with and without mycorrhizas and found that the infected plants grew slightly better at the planting-out stage, although any advantage disappeared completely after two seasons in the ground. This was because all the plants ended up infected with mycorrhizas anyway. Finally, a test by Which? Magazine found that the potting compost brand that contained mycorrhizas performed poorly, although such an outcome may be down to other factors.

So are mycorrhizas products any good at all? In all probability mycorrhizas products will be unlikely to confer any long term benefits to your plants, unless you have good reason to suspect that your soil is deficient in mycorrhizas. (It is important to check that your plant can benefit from mycorrhizas in the first place.)

Heavy use of phosphorus in agriculture reduces the incidence of mycorrhiza in the soil. The element is also used to ignite matches.

As already stated, heavily cultivated ground may reduce the occurrence of mycorrhizas. This is because fungicide is naturally destructive to fungi, although, interestingly, it is phosphorus-rich soil that is especially detrimental to mycorrhizas. Mycorrhizas usually function to gather this rare resource for plants, but an abundance of it, usually created by fertiliser, actually suppresses it. Why this is the case is unclear, although it can be in a sense expected, as messing with the ecosystem can have untold effects. Sadly, in this case using mycorrhizas rootgrow is unlikely to have any effect, as if the soil is not conducive to mycorrhizas, the best option will be to stop using phosphorus rich fertilizers, and wait for the mycorrhizas to return naturally.

There may be reason to use mycorrhizas in some cases, perhaps for isolated plants, and plants that are indoors (although such cases are unlikely to be common).

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Hedging, Jorge, Plants

alternatives to buxus

Forgoing box is a real shame as it possesses all the characteristics required for low maintenance natural hedging. It responds well to clipping, and is slow growing, often needing to be cut only once a year, with growth usually between 10 and 15cm. It is also frost resistant and native to the UK, being cultivated since at least Roman times. Sadly, due to the current box blight epidemic, box is no longer the premium option, as the disease can destroy years of work to which the gardener can do little to stop. However, using other plants can be seen as a great opportunity to experiment, which makes gardening so enjoyable in the first place. There are so many underappreciated alternatives that can produce stunning delineated gardens.

Obviously, no plant will be exactly like box and the shape (and colour) of your hedge could be very different. If you wish for a substitute for box, however, Privet (Ligustrum ovalifolium) is a highly popular choice that is extremely hardy and small leaved, although sadly fast growing; henceforth, it will need to be trimmed multiple times in the summer to encourage dense growth. As it is only semi-evergreen, there is also the possibility of the plant shedding its leaves in extreme bouts of cold. Another possibility is switching to artificial topiary that is visually identical to box, and virtually indestructible, although its shape is limited to the manufacturer’s designs.

alternatives to box

Other worthy alternatives include the Griselinia littoralis, Euonymus japonicus and Elaeagnus ebbingei. The Griselinia is notable for its soft glossy leaves, average growth rate and responsiveness to clipping. The Euonymus is usually two-tone with cream bordering the edges of its otherwise green leaves, although it can variegate greatly in full sunlight. The plant is hardy and suitable for nearly all soil types, although will need maintenance to ensure denseness. The Elaeagnus is a great alternative as it is dense, hardy and responsive to clipping. It is also fragrant in the autumn with the emergence of white flowers.

One of the best species of natural hedging has to be the Taxus baccata, commonly known as the English Yew or Common Yew; it is very hardy, average growing, dense and great for birds, which love its berries. For more colourful alternatives, lavender (Lavandula angustifolia) and sometimes heather, can be grown into hedges. Key for lavender is to cut it before it flowers, or otherwise it will lose its shape. It is great for wildlife, fragrant and evergreen.

common yew

Due to the box blight epidemic, the RHS Garden Wisley are currently trailing 25 alternatives to boxwood. The varieties that have performed well include such plants as the Kilworth Cream (Podocapus nivalis), Sunshine (Ligustrum sinense) and Tom Thumb (Pittosporum Tenuifolium). The team has found that the Podocapus versatile, and responsive to clipping; the plant itself can be described as extremely small leaved, and darker in colour than box. The Ligustrum is slow growing with vibrant yellow leaves, the Pittosporum purple and compact. Also of interest is how the Pittosporum is a source of food for animals in its native New Zealand and is thus hardy and responsive to clipping.

Do you have any experience growing hedges? We’d love to hear from you. Post in the comments below!

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Gardening, Hedging, How To, Jorge, Pest Control

treating box blight

Ever since the 1990s, gardeners have had to witness the destruction of their natural hedging projects due to the emergence of new fungal diseases targeting Boxwood (Buxus sempervirens). This has only been exacerbated with the introduction of the Box Tree Caterpillar (Cydalima perspectalis) that began appearing in gardens since 2011. (It was likely imported from the Far East in 2008.) This has affected many famous gardens and gardeners with even Monty Don witnessing the decimation of his 15 year ornamental hedge project. The blight is so deadly that the preferred option for many gardeners is to simply destroy the affected plants, as even plants that appear to recover are often destroyed with the re-emergence of the fungus. Others have abandoned Box entirely by switching to Box alternatives. However, one need not abandon box altogether as both problems are preventable and treatable, although the blight requires great time and effort to combat. Other less common problems include: Box Rust, Box Sucker, Box leaf-mining gall midge, box red spider mite and mussel scale.

Treating Box Blight

The two most serious forms of Box blight are Cylindrocladium buxicola and Volutella buxi, which often appear together. The former is highly destructive and can kill a plant in a matter of days. It is characteristic for producing discoloured leaves that are white on the underside with brown lesions on the top. In humid conditions, the fungus may result in black streaks on stems. The latter turns leaves yellow, darkening them to a shade of tan. How they enter the plant is also different as the Cylindrocladium enters through leaf cuticles in humid weather, while the Volutella requires a cut leaf surface. Both diseases are treated together with the same methods, although favourable growing conditions may allow the Box to recover from the Volutella without such an intervention.

Treating Box Blight is difficult, but can be done, although there is no guarantee of success, and it may be preferable to simply burn the affected box to safeguard the rest. Key is to prevent further contamination through disinfecting your tools, along with your clothes and boots that sticky spores can attach. We recommend that you use liquid copper to clean your tools. (It will kill the spores.) Now with the affected plant, it will need to be hard pruned in the affected areas, the branches burnt. The cut areas will then need to be treated with fungicides that contain tebuconazole or tebuconazole and trifloxystrobin. Any leaf debris should be picked up and destroyed and the top layer of soil removed and replaced. (Spores can stay in the soil for a whopping six years!) We recommend that you do not use fertiliser, as high nitrogen produces vulnerable growth. Instead, mushroom compost can be used as mulch to provide aeration and better microorganism balance. Finally, important to note is how the diseases are suited to humid conditions where air movement is restricted. Therefore it may be necessary to open up the compact framework of your box – a process known as halting clipping.

If you are unaffected by blight yet, or wish to prevent blight from entering new areas of the garden, prevention is better than adaption. When bringing in new box keep it quarantined and watch for symptoms. To do this, you can either leave it for six weeks untouched, or create humid conditions and leave it for 3 weeks. As the fungus thrives in such conditions, the blight will appear by then. (Sadly, some nurseries use fungicides to hide such symptoms, so it is necessary to be cautious.) Again, preventing humidity is key, and can be achieved through watering at the base of the plant rather than at the foliage, and by positioning the Box away from overhanging plants. Also important is not to clip when rain is forecast, or the plants wet. Finally, it is recommended that you provide adequate ventilation for better airflow, spacing the Box around 30 cm apart from each other.

A Look to the Future

buxus

For now it appears that box blight will run rampant over gardeners’ painstaking creations, but there are a number of blight resistant cultivars being developed in Europe that should appear on the market in a few years.

Treating Box Rust

Box rust (Puccinia buxi) is another common problem that affects Box and is symptomatic for orange pustules on both sides of the leaves. It is usually harmless and is treated through cutting off the affected areas or using fungicides for rust diseases such as tebuconazole, tebuconazole with trifloxystrobin and triticonazole.

Stopping the Box Tree Caterpillar

stop box caterpillar

The Box Tree Caterpillar can leave patches of dieback much like box blight, and is distinctive for patches of webbing and frass droppings. Young Caterpillars are greenish-yellow with black heads, while the older ones have thick black and thin white stripes along the body and are up to 4cm long. Like most insects, they are most active during the warmer months, but can overwinter in webbing spun between leaves. To deal with them, they can either be picked off by hand, or dealt with insecticides that include ingredients such as pyrethrum, deltamethrin, lambda-cyhalothrin, and acetamiprid. (It is recommended that you do not spray plants in flower as this could deter potential pollinators.) Like box blight, prevention is preferable to adaptation so it is recommended that you check new plants in nurseries.

Other Box Problems Caused by Insects

  • The Box Sucker (Psylla buxi) can distort your box by turning the leaves into mini-cabbages. (Oh, No!) The insects suck the Box’s sap and leave chemicals that retard new growth. It is not usually serious, but can be controlled with the above insecticides and clipping.
  • The box leaf-mining gall midge (Monarthropalpus flavus) effects Box through causing a yellowish discoloration of the leaves. This discolouration is caused by the fly’s larvae that hatch and feed inside the foliage. It is, again, unserious and not usually worth treatment.
  • Mussel scale (Lepidosaphes ulmi) are tiny mussel shaped sap-sucking insects that usually attach to bark, but on occasion will appear on leaves. Small infestations are not worth treating, but larger infestations can be treated with the above insecticides or organic sprays such plant oils. Such treatments are best applied in May and June when the next generation is emerging and vulnerable.  
  • The box red spider mite (Eurytetranychus buxi) is another sap-sucker that feeds on the undersides of leaves, causing a fine white mottling. While the mites are difficult to exterminate, they do not seriously damage the plant; the bugs can be treated with fatty acids and plant oil sprays applied continuously in five day intervals until the all the life-cycles of mites are wiped out.

Have you had trouble with box blight? We’d love to hear how you coped. Post in the comments below!

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Animals, Garden Design, Jorge, Water Features

john-constable-water-feature

With the psychological benefits associated with water, it is no wonder water features are an integral part of garden design. Since at least the eighteenth century, doctors have prescribed trips to the seaside to improve their patients’ well-being. Britain’s love affair with water stretches all the way to Aquae Sulis, located in what is today Bath; there both Briton and Roman alike would seek relaxation in its natural hot springs.

Access to water is known to both alleviate stress and promote serenity. For example, psychologists from the ‘Blue Gym’ project found that people have preference for images with water than those with none. Interestingly, the same project found that images with both blue and green garnered the most favourable response (an interesting tip for those designing their garden).

So why is this the case? Why do humans love blue and green? It is probable that our love for water is hard-coded in our genes to ensure our survival. It is a hangover from when humans were hunters and gatherers, when the colours of blue and green signalled a resource rich environment that was conducive to your long term survival. To our savannah-dwellings ancestors, habitat selection was of paramount importance, and lush grasslands and clumps of trees provided evidence of abundant wildlife and a good supply of water.

john-constable-river

It is not incidental that rivers, lakes and seas are blue, and plant life green. Only a combination of both could ensure survival and a view of both signalled the jackpot. It is from this that humans have developed a sense of pleasure when we witness such a view. While now such a view is not necessary for survival, the genetic heritage remains as evolution takes place over extremely long periods, far beyond the 20,000 odd years humans have been living in permanent settlements.

Humans’ preferences for certain habitats have been confirmed in a number of surveys. In one, people from around the world were all shown standardised photos of five landscapes – deciduous forest, tropical forest, open savannah with trees, coniferous forest, and desert – and no category stood out, except that of the desert, which had a slightly negative response. (It is, unsurprisingly, an environment that is both hostile to human life and resource scarce.) When the experiment was extended to young children, they expressed a marked preference for the savannah (where early human evolution took place) as well as landscapes with water, trees, game animals, and cloud patterns among others, which offer opportunities for both food and water.

savannah-environmental-preferences

In another survey, a professional polling organisation conducted a poll of art preferences in ten countries in Asia, Africa, Europe and the Americas, and found that blue was the most popular colour, followed by green. And again, there was a marked preference for water, plants, and large animals, both wild and domestic, among others.

Indeed, it is likely that such colours also provide animals a rudimentary pleasure as such environments sustain the majority of life on earth, provided they in fact see in colour. Indeed, animals with comparatively low sentience may find it hard to enjoy anything else.

roman-aqueduct
The Pont du Gard, the most famous Roman aqueduct in existence – it was modified in the 1740s to carry a wide road.  Emanuele  (2007)  licensed under CC BY-SA 2.0.

Now, when do man-made water features pop up in human history? Famously, the Romans built a system of aqueducts to supply the city of Rome with water, which was necessary to feed the expanding metropolis. These aqueducts utilised gravity to transport water from the surrounding hills, which was then stored in large cisterns. From these cisterns, the water would then travel through pipes to public distribution points and individual’s houses where there might be fountains. To power these fountains, the Romans again utilised gravity, as because a foot of height generates 0.43 pounds per square inch of water pressure, even a small cistern could power a fountain. As a sidenote, the Romans were not the first to use gravity to power fountains as even such primitive societies such as the Maya did so.

The power of gravity could be utilised in other ways to power fountains. Jumping forward to the 18th century, King Louis XIV’s fountain complex at Versailles was powered by the river Seine. It utilised an convoluted system of 14 huge water wheels to power pistons for over 200 water pumps. The water was transferred through a system of reservoirs up the hill into an aqueduct, which then distributed the water to the various fountains on the grounds. In the intervening years between the romans and Versailles, fountains would find their greatest popularity in the Islamic world (in the famous paradise gardens), and later renaissance Italy. It was in these two golden ages that saw the emergence of such artists and engineers that could enable their construction. The surviving examples from these periods are still highly popular today.

renaissance-water-fountain
The Fontana Masini in the Piazza del Popolo in Cesena, completed in 1591. It was designed by Cesena Francesco Masini and built by the stonemason Montevecchio Domenico and his assistants.

Other more complicated methods of pumping water emerged in time such as hydraulic rams and steam engines. The former is not too dissimilar to the water wheel in that it requires no power other than the kinetic energy of flowing water. The device, in effect, takes in water at one height, and outputs water at another higher height. It was invented in 1796 by Joseph Michel Montgolfier, who is otherwise famous as one of the inventors of the hot air balloon. The steam pump, and its successor the electric pump, would prove revolutionary and greatly increase the power of fountains, enabling such fountains as the King Fahd’s Fountain that produces the largest water jets on earth, possibly surpassing a 1,000 feet.

largest-fountain-on-earth
King Fahd’s Fountain, located in Jeddah, Saudi Arabia.

Now, returning to the original question, a water feature is likely to signal a plentiful supply of water, and allow one to feel relaxed, and at home. Even better, the sound of running water will allow such relaxation when in earshot. Then, once placed in the greenery of the garden, it provides the perfect environment for a human to relax. Now thanks to advances in technology, you can use solar energy to power your feature, allowing one to both save money and reduce greenhouse gas emissions.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

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