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mychorrizae

Mycorrhizal Fungi; an argument against fungicides.

Today I want to get a little bit deeper into the science of bowling green ecology, but I’m getting a little tired of the Ecology title sequence I stupidly started 9 articles ago. Instead of continuing to label them Ecology 1,2,3…etc, I will give them a tag of their own so that if you’re looking for them on the site you just need to type ecology into the search box.

Mycorrhizal Fungi (mycorrhizae) are specialised fungi that work with our grass plants to form symbiotic relationships with the roots.  Most soils contain these fungi and each type has its own peculiar host preference. (i.e., each plant species has a specific species of mycorrhizae that it prefers to work with).

The name comes from the Latin word mycor meaning fungus and rhiza meaning root. “Mycorrhiza” is the singular form and “mycorrhizae” the plural and, in soil science the name refers to the tissue that forms when fungi and roots develop a symbiotic (mutually beneficial) relationship.

One of the key benefits to our grass Read more

Performance Bowling Greens

Ecology 8. More disturbing news for bowling clubs

Last time, I introduced the subject of Disturbance in bowling green ecology and maintenance. I finished by posing the question; How can we use disturbance theory to our advantage in our quest to create a Performance Bowling Green?

To answer that, let’s look at what might constitute Disturbance in the average bowling green. As greenkeepers we actually have an impressive amount of potential influence we can bring to bear on the turf environment; some good and some bad. We can think of these influences as pressures and by applying them with the right force we can manipulate the bowling green eco system (to some degree) to our advantage.

Last time we also discussed Stress factors, which when compared with physical disturbance from our machinery and bowling, can seem innocuous, but the overall affect of say LDP can easily be more damaging to our turf in the long term than an obvious physical disturbance like hollow tining.

Every day Greenkeeping and bowling can have a high disturbance value and put the very grass we are tending under a lot of stress. Mowing, verti-cutting, wear from bowling, pests, diseases, disorders, aeration, top dressing, water and nutrient availability and soil pH can all cause stress to a greater or lesser degree and this will change depending on grass species, general green condition, weather and soil type/condition.

Well the answer is clear then isn’t it? Maybe Read more

Disturbance theory

Ecology 7. Disturbing News for Bowling Clubs

In 1988, Grime, Hodgson and Hunt published their study called “Comparative Plant Ecology – A functional approach to common British species”, which on the face of it sounds like ideal bed time reading for insomniacs. However, the work these scientists carried out might make you sit up in bed and take notice when you realise how relevant it could be to the performance of your bowling green.

In this work, the authors state that vegetation that develops in a place at a particular time is governed by environmental pressures. These pressures may be categorised as stress, disturbance and competition (S, R and C) and that these vary in their relative intensities. Individual species develop their own growth strategies in order to deal with their own environmental pressures.

In Performance Bowling Greens, I introduced the concept of Disturbance Theory which is simply a way of thinking about and defining the growth strategies of each of the fine grass species we aim to grow on our bowling greens. Furthermore, by relating this Disturbance Theory to our greenkeeping calendar we can develop programs and strategies to help us create the environmental conditions that favour the species we know will produce the finest bowling surface. In the UK these are the bent and fescue grasses, but Disturbance Theory holds up for any environment, including the warm season areas of the world. Read more

Life after pesticides for bowling clubs

Ecology 6. Soil Microbes

Soil microorganisms exist in vast numbers in the soil as long as there is a carbon source to provide them with energy.

The microbial population is made up of 6 distinct groups of organisms. In order of average population size (biggest first) there are Bacteria, Actinomycetes, Fungi, Algae, Protozoa and Nematodes.

The actual biomass of each of these organisms can be confusing at first due to the difference in size of the individuals. For example, due to their small size, Bacteria contribute a smaller overall biomass than Actinomycetes, even though these organisms are a factor of 10 times smaller in number. Due to these Actinomycetes being larger as individuals they contribute a similar biomass to the much more abundant Bacteria.

Fungus population numbers tend to be smaller but are usually the dominant presence in the microbial biomass where the soil is left undisturbed. Bacteria, Actinomycetes and Protozoa are hardier making them more able to tolerate disturbance of the soil than fungal populations. Bowling greens are probably a half way house; not being subjected to excessive tillage, but not entirely undisturbed either.

Here’s the really interesting bit:

There are more microbes in a teaspoon of soil than there are people on the earth!

The Circle of Decline is largely predicated on poor soil microbial populations due to inappropriate maintenance practices.

the Circle of Decline, the reason many greens never improve
the Circle of Decline, the reason many greens never improve

Microbes and plant nutrition

Soil microbes are abundant in the soil and are vital to the recycling of organic matter in the soil to provide nutrition for plants. The smallest and most hardy of these are the Bacteria which can survive under the harshest of conditions and are especially resistant to tillage or the mechanical cultivation of the soil as happens in the top 100-150mm of the bowling green through aeration practices.  Fungi are more specialised and need a constant food source meaning that they survive and thrive more readily in uncultivated soils.

Soil organic matter consists of a mix of living microorganisms, dead leaves, shoots and roots (fresh residues), and the older decomposed plant material called humus. Fresh plant or animal material provides an ideal food source for microbes and is composed of easily digested sugars and proteins.

Soil cultivation through aeration (incorporating oxygen) destroys soil organic matter through oxidation and allows bacteria and other microbes to rapidly decompose organic residues. Warmer soil and the presence of moisture speeds up this process by supporting an increased microbial populations in the soil. Organic matter with a low carbon to nitrogen (C:N) ratio (green material) is easily decomposed and nutrients are quickly released (4 to 8 weeks), while organic matter with a high C:N ratio (woody material like roots, rhizomes and stolons) decomposes more slowly and the microbes will tie up soil nitrogen to decompose the residues. Protozoa and nematodes consume other microbes in the soil and release the nitrogen as ammonia, which becomes available to other microorganisms or is absorbed by plant roots.

Bacteria Graphic http://www.soils4teachers.org/

 

eco systems

Ecology 5. Environmental pressures

Keeping the bowling green eco-system in balance is important in order to minimise the exposure of our grass plants to a range of environmental stresses. These stresses can be thought of as environmental constraints to growth and regeneration and can come in many guises, such as a shortage of light, water, nutrition or extremes of temperature. Conditions within the soil can induce stress in the grass plant. These include soil acidity/alkalinity (pH), soil fertility and soil salinity (salt levels).  Outside factors can also play a part in stressing the desired species within a green. For example shading by trees or inappropriate maintenance such as over/under watering of the turf.

Disturbance

One of the most questioned sections of my book Performance Bowling Greens is the section on disturbance. Disturbance in greenkeeping refers to the partial or total damage/removal of living plant tissue. Although this can be as a result of pathogenic organisms like pests or diseases, it can just as commonly be caused by wind, skinning by heavily delivered bowls and wear from bowling and maintenance traffic. However, the area that raises most questions is the fact that many greenkeeping practices cause disturbance too. Maintenance operations considered essential to the green’s health such as scarification, verti-cutting, aeration and even mowing also contribute to disturbance related stress.

Disturbance theory in bowling green management argues that the more we disturb the surface and the more intensive the maintenance, the more stress we put on plants, which makes aeration practices sound as if they might be counter productive. On completely natural grasslands such as the Machair or meadows this would indeed be a true assumption to make as these are perfectly balanced eco-systems. The majority of bowling greens are not and although it is possible to get to that perfectly balanced state in theory, the future for almost all bowling greens will include disturbance by maintenance.

The trouble with disturbance is that it puts further pressure on the grasses inhabiting the disturbed areas. This means that we must cultivate grasses that are capable of the rapid recovery or regeneration needed to not only tolerate the stress, but to actively exploit regular disturbance. One species that does that already is Poa annua which is quick to capitalise on situations like this, making it a very successful competitor in bowling greens to the extent that it makes up a large proportion of the sward on many greens. Poa annua of course brings with it a lot of trouble as it isn’t ideally suited to the production of a fine, uniform bowling surface, although it can be refined over the longer term through maintenance.

Conclusions

The trick in ecology is never to assume that because something has traditionally been seen as bad for bowling greens, that it needs to be eradicated, as bowling greens are eco-systems like any other. Our understanding of eco-systems and all of the inter-relationships that exist within them is poor to say the least.

An example of where we might be throwing out the baby with the bath water is our use of pesticides. For example, we know that there are many millions of fungi in the soil beneath our greens and that some of these are highly specialised. One specialisation is that some fungi have symbiotic relationships with grass roots, allowing the grass plants to draw nutrients from a much larger volume of soil than they can on their own. It is likely that the use of fungicides has a detrimental effect on these relationships.

Staying on the subject of fungi, the ones that we know most about as greenkeepers are the pathogenic ones like fusarium that can devastate our turf. A flawed assumption is that fusarium somehow turns up at our green to cause this damage at certain times of the year, usually autumn and winter. You will often hear claims that the fungus has been imported to the green by one of many mechanisms such as on a contractor’s machine or in a bag of top-dressing. The fact is that all greens, especially healthy, balanced greens will play host to fusarium to some extent and it’s even possible that it usually plays a beneficial role in the soil. Furthermore, even if we wanted to introduce fusarium to our green, bringing it in from an outside location would be unlikely to result in success for the same reasons that it is very difficult to achieve success when over-seeding bowling greens; the established indigenous organisms will always have an advantage over the imported ones for whom the competition will almost always be too strong to allow them to establish a community.

Ecology is about balance and to achieve this balance there is a constant turmoil as organisms fight to exploit their particular niche within the eco-system. If, by design or bad judgement we make our greens more attractive to fusarium than it is to bent grass we will get a severe outbreak of what we see as fusarium disease. If, on the other hand we keep thatch under control, manage compaction well and ensure that our green provides the ideal environment (which will almost certainly also include a population of fusarium) for bent grass we get what we see as a performance bowling green. Beauty is in the eye of the beholder, it just depends who the beholder is!

LDP, localised dry patch on bolwing green

Ecology 4. Biotic and Abiotic Factors in Bowling Green Eco-systems

Moving on in our crash course in bowling green ecology, we can’t fully understand the stresses and competition that exist below our feet until we appreciate the range of factors that contribute to, or play a part in the everyday life of our grass plants. There are 2 main groupings of factors that affect our turf’s chances of success and these are as follows:

Biotic Factors – this describes the living components of the bowling green ecosystem and includes fungi, animals and plants, including our bowling green grasses.  These organisms may co-exist with no interaction, form mutually beneficial relationships known as symbioses, or indeed become pathogenic and cause damage to our grass plants.

Abiotic Factors – these are the non-living components such as the climate, soil fractions (the mineral component of soil such as sands, silt and clay), water and soil bound nutrients.

All of these factors affect the inhabitants of the eco-system to some degree. Maybe in a small way, like the minimal affect of fusarium on strong, healthy turf or more dramatically such as when there isn’t enough water available to plants due to drought.

Biotic factors in bowling green management.

These include:

  • Fungi, which can be beneficial and/or pathogenic
  • Insects,which can be beneficial and/or pathogenic
  • Weeds
  • Turf Disorders, such a Localised Dry Patch
  • Bacteria
  • Nematodes
  • Humans

These all constantly and dynamically interact within the soil profile and as a result can influence the development of the turf and the species present.

Biotic and abiotic factors interact with each other. For example low oxygen levels in turf (abiotic) will affect the health of the turf roots directly when the soil becomes increasingly acidic making it harder for roots to extract nutrients from the soil, and indirectly by reducing the population of beneficial bacteria (biotic factors) which play a role in breaking down organic material to release nutrition.

Many of the processes occurring in the Nitrogen cycle are due to biotic activity. This biotic activity relies on the abiotic environment to operate effectively, for example soil temperature and oxygen levels, being sufficient to allow Nitrogen release to continue unhindered at a rate that is beneficial to the turf.

Abiotic factors in bowling green management.

These include:

  • The Soil Fractions: sand, silt and clay
  • Water quality and quantities available
  • Climate: temperature, light levels, day length, rainfall, humidity

Common Abiotic stresses of turf include frost damage, wind damage, heat and drought damage, freezing, compaction, flooding, salt injury and fertiliser scorch.

Next time we will look a bit closer at the stresses our turf has to deal with and the coping mechanisms it has developed to help it deal with these.

Annual Meadowgrass

Ecology 3. Competition and Adaptation

In my previous post we discovered a new range of terms to come to terms with when we start to think of the bowling green as an eco-system. While some of these were a bit obscure, like Rhizosphere, most of them are self explanatory. The term Niche, is one of these. We all understand the need to find our own niche in life (well, maybe…I’m still looking for mine:-) Niche describes the unique collection of conditions required to enable our desired grass species to thrive. It’s a good ecological term to keep at the forefront of your mind when developing a program of maintenace for your green.

The process of evolution appears to rely heavily on the struggle between organisms for dominance in any particular environment and our bowling greens are no different.

Competition

Competition is another key term in ecology and comes into play when two populations share some aspect of a niche, such as a food resource. There can be a variety of results from the competition between populations, the most common being:

  1. One population will compete more effectively for the available resources. The population that is more effective will eventually “win” and drive the second, less effective population from their niche. With the niche freed, the winning population will grow to the carrying capacity of the niche.
  2. Both populations will evolve into less competitive niches. If two populations compete on even terms, it may be beneficial for both populations to modify their niches so that the populations’ niches overlap less or not at all.

Poa annua

In bowling green maintenance there is one species that illustrates this concept better than most.

If an organism can compete and adapt quickly to a changing environment then it becomes a pioneer in a range of ecosystems and habitats, and Poa annua (Annual Meadowgrass) is clearly well adapted to competing in a variety of environments. To achieve this level of adaptability it has an impressive arsenal to call upon, such as:

  1. Heavy seed production.
  2. Flowering and seed production throughout the year.
  3. Flower heads that stay low to the ground to escape the mower and even grazing animals.
  4. Fast germination of seeds to help new plants establish and get a hold in the soil quickly.
  5. Poa annua thatch produces toxins which can prevent the germination of the seeds of other species.

Bowling green ecology is no different to the wild in many respects even although the grass has a strong ally (or foe sometimes) in the greenkeeper. Plants compete for physical space, for nutrients and water from the soil and for sunlight. In turf areas the ability to monopolise the resources of their environment at the expense of any other grass or weed species gives our desired species (usually bentgrass and/or fescue) the edge.

To form a densely populated, high performance bowling surface requires our favoured species to suppress the other species by removing their access to the vital resources of:

  1. Light – by growing above and over the other species to suppress access to sunlight.
  2. Physical space – by tillering (producing new shoots) and spreading quickly into spaces not yet taken in the soil.
  3. Nutrients – by producing more invasive and/or exploratory roots that can monopolise the food resource leaving insufficient for other species to thrive.
  4. Water- drought tolerant grasses can use summer drought to move into areas where less drought tolerant species have died back.

A Performance Bowling Green Management Plan takes account of natural changes at turf level and within the soil, and adapts to allow for changes in management practices, climatic changes and seasonal changes.

Environmental Stresses

Some of the key factors that benefit or hinder a species in its quest for dominance are described as Environmental Stresses. It is these stresses that drive the evolutionary process and as such can be used by the bowling greenkeeper to create conditions that are more suitable for the desired species than for others. There are a number of ways for greenkeepers to manipulate the environment artificially, or indeed to take advantage of naturally occurring stresses, in order to alter the balance of the bowling green ecosystem in favour of the desired grass species. 

And next time, we’ll look more closely at Environmental Stresses, the problems they cause and the ways in which we can exploit them for our own ends in bowling green maintenance.

ecology

Ecology 2. Ecological Terms for Bowling Greenkeepers

Ecology is the study of the relationships between plants and other organisms and the environment in which they exist.

When developing a maintenance program for a bowling green we need to take account of its ecology in terms of the relationships between the grasses we hope to encourage and their interaction with their living and non-living environment.

However we choose to interact with this bowling green ecosystem (with or against nature) we will be working within a dynamic, constantly changing environment and it is vital that we understand this before stepping off into a new program of maintenance. In other words we need to think of our green as an eco-system.

Ecosystem is the name given to a system formed by the dynamic interaction of a community of organisms (not just grasses) within their specific physical environment. 

Ecology is a specialised branch of science that has its own set of definitions and terms and it will be useful to understand a handful of these as we go on:

Rhizosphere-  This is the 5mm zone that surrounds the roots of our grass plants. It is a very active zone and a very important one for greenkeepers to consider as it includes critical influences on the health of our grass plants like the movement and availability of water, the populations of bacteria and fungi and it influences nutrient and moisture uptake, which has a knock on effect to the vital processes that go on within the plants. Read more

Smoothness and Colour

Ecology 1. Pesticides

This is the first in a series of articles looking at the fundamentals of Greenkeeping in a lead up to the introduction of a range of new resources here on Bowls Central.

I always welcome questions from readers and each week I receive emails asking questions about the best chemicals to use for a range of problems encountered on bowling greens.

Agriculture and Horticulture are huge industries and an appropriately huge range of companies exists purely to serve them and provide us with everything we need to make our bowling greens better. So far so good then? Well, yes, but only to a point.

Over the decades we have grown accustomed to treating symptoms and as a bigger and better range of chemicals has appeared on the back of agricultural research we have adopted the attitude of large scale farming. That attitude says that we should take out all of the doubt and risk that is inherent in Nature and try to circumvent this through the use of clever landscape designs like USGA specification greens and management tools like artificial fertilisers and pesticides.

I hold the opinion that Read more