Saturday, 15 December 2012

Wrap Up Warm



The following information is by James Hartley, Director, English Garden Group, an up-market garden centre in Valbonne.  Interesting topics I thought for our group.  I've put his tips in 4 topics:
  1. Direct or "radiation frost".
  2. Winter protection fleece.
  3. Ease off on fertilisers.
  4. Frame to  protect climbers.
Direct or "radiation frost":

Direct or "radiation frost" is always a danger when the skies are clear, with the warmth remaining on the land's surface after a sunny winter day being rapidly leaked away by radiation into the clear night sky.  This effect is so dangerous due to the sheer speed with which the heat is lost:   in many cases the temperature of the leaves of the plants will actually drop below the ambient air temperature as heat radiates away.  As if this wasn't bad enough, the effect is compounded as the sun bursts out the next morning, rapidly defrosting the leaves and in the process, bursting the cell walls within the leaves.


Winter protection fleece:

If the plants are too large or if it isn't practical to move them, then you have to bring the cover to the plants, and this involves large quantities of winter protection fleece.  Winter protection fleece is a breathable fabric that helps to create a small microclimate in the canopy of your plant, keeping the temperature of the leaves several degrees above the ambient temperature, in particular under conditions that could lead to the reverse.  The word "breathable" is crucial:  never ever use plastic directly over plants as this allows moisture build up and rotting to start in the leaves and outer branches.  The membrane sheets provide the protection required against heat radiating away and wind stripping the warmth from the leaves, whilst allowing moisture to permeate out and away each day.


In extreme cases even evergreens and other hardy plants can be affected when the soil becomes frozen and the morning is particularly warm.  Roots then find it impossible to lift moisture up to the plant and the plant can die from drought.


Ease off on fertilisers:

Fresh tender leaves are far more susceptible to frost damage than leaves that have been on the plant a while and have had time to harden off.  To this end - make sure you ease off on the use of fertilisers containing high levels of nitrogen towards the end of the year as these will push plants into extended vigorous growth - leaving you with foliage that is badly unprepared for the ravages of a cold winter.  If you are keen to keep your plants well fed, then opt for balanced feeds later in the season, or better still, feeds with elevated levels of potassium.



Frame to protect climbers:

Attaching fleece to a climber on a wall to stay up for an entire winter can be difficult to do effectively.  This problem however can be solved elegantly with a couple of slats of wood.  The strips of wood in question should be light, no more than about five or ten centimeters wide and a couple of centimeters thick, and should be as long as is required to be mounted vertically on the wall to match the height of the climbing plant you are trying to cover.  Drill two or three holes (top, bottom and centre) in the strip, and hold the strip up to the wall on either side of the climber and mark the wall in position of the holes. The wall can then be drilled and fitted with  plugs to take screws.  In this way you can screw the wood batons to the wall and use the wood to staple up the fleece.  Starting on one side the fleece can be drawn over the plant, stapled on the other side and drawn back across in the same way a couple of times, stapling on each side, to create a protective layer that is both effective and reliably attached.  Once winter is over, the fleece can be removed, and the wood strips taken down simply by removing the screws, allowing them to be stored and reused the following year.



A word of advice:  be sure to drill the holes identically in each of the wood batons to avoid having to figure out in which position and in which orientation each piece of wood goes the following year.

Sunday, 2 December 2012

Bumblebees and Honeybees

The bees that most people can easily recognise and identify are bumblebees and honey bees.






Bumblebees


Bumblebees [Bombus terrestris] are related to honeybees [Apis].

Bumblebees, which we think of as very furry black and yellow striped creatures with pollen sacks on their legs, also live in colonies, feed on nectar and gather pollen to feed their young.  They also produce small amounts of honey.

They are mostly found in higher latitudes and / or high altitudes and there are around 250 known species in the Bombus genus.

They form colonies, although these are much smaller than honey bees, and are usually underground or in mounds of grasses.  They don’t usually keep the colony from one season to the next and it is a queen that has overwintered that will start the construction of a new nest in the Spring.

Bumblebees will visit patches of flowers up to 1-2 kilometres away from their colony and will continue to visit for a long as they continue to find both nectar and pollen.  Some species can leave a scent mark on a flower which deters other bumblebees from visiting whilst the scent marks lasts.  Apparently they also differentiate between rewarding and unrewarding flowers !

Bumble bees are important pollinators of both crops and wildflowers.  People are increasingly using bumblebees as pollinators, especially for plant species that others cannot pollinate, using a technique known as ‘buzz pollination’

Certain plants hang on to their pollen more firmly in their anthers, which are typically tubular with an opening at only one end and the pollen inside is smooth and firmly attached.

Some species of solitary bees and bumblebees use this method – also called sonication – where the bee grabs onto the flower and moves its flight muscles rapidly, which causes the flower and anthers to vibrate, dislodging the pollen.  8% of flowers in the world are primarily pollinated by buzz pollination and the following are those that are more efficiently pollinated :
  • Many members of the Solanaceae family, including many species of the genus Solanum
  • tomatoes
  • potatoes
  • aubergines or eggplants
  • Some members of the genus Vaccinium
  • cranberries & blueberries
  • Senna
Other plants are
  • Arctostaphylos – manzanitas
  • Dianella – Flax lily
  • all Dodecatheon – shooting stars
  • Heliamphora
  • Hibbertia


So, the reason for engaging the use of bumblebees is to pollinate, particularly, greenhouse-grown tomatoes and aubergines, which require pollinating to produce any fruit.  Apparently, pollination used to take place by using electric vibrators (!) – one brand name was ‘Electric Bee’ – but using bumblebees was found to be far more cost effective than human labour and cut out the inevitable breakages of plants within the confined space of the greenhouse.

In Australia there are no native bumblebees and they have suffered a number of widely publicised environmental disasters, caused by introduced species that have escaped.  Research is being carried out to see whether the native Blue Banded Bees can be used for the task, but this is meeting lobbying by bumble bee importers who seem to prefer to disregard this risk and any ‘home-grown’ solution !

The agricultural use for bumblebees is, however, limited to pollination as bumblebees do not overwinter the entire colony and so are not obliged to stockpile honey for food.  So they are not useful as honey producers.


Honeybees


Honey bees, of which there are seven recognised species, but with a total of 44 subspecies in the Apis genus, would appear to have a centre of origin in South and South East Asia.

The European or Western honeybee [Apis mellifera], which seems to have originated in eastern tropical Africa and spread to northern Europe and Asia, is the most commonly domesticated species and has the distinction of being the third insect to have its genome mapped – 28 October 2006.

The name was given to them by Carl Linnaeus in 1758 and the mellifera part comes from the Latin : melli meaning ‘honey’ and ferre meaning ‘to bear’ – so, ‘honey-bearing bee’.  However, he realised that they do not bear honey, but nectar and later tried to correct this to Apis mellifica [‘honey-making bee’] in a later publication.  According to the rules of synonymy – which is the scientific nomenclature or name – the older name has precedence.

Apis mellifera is not a native to the Americas and were taken there by colonists, although there were other native species that were kept and traded by the indigenous peoples.  The colonists also introduced the dark bee [Apis mellifera mellifera] and later the Italian bee [Apis mellifera ligustica] and others.  Many of the crops that depend on honeybees for pollination have also been imported since colonial times.

Again, to anyone reading this who has a greater in-depth knowledge of bees, this is only meant to give an outline of how bees work and how a hive functions – there is so much fascinating detail that I have been obliged to leave out, otherwise I would be producing an Encylopaedia-Britannica-length post !

Honey bees live in very organised colonies averaging between 40 000 to 80 000 bees in a healthy hive in mid-Summer.

There is one Queen to the colony – she is the only fertile female and lays the eggs from which all the other bees are produced.  She mates with the Drones.

The Drones are male bees, which represent approximately 10% of the hive colony.  Their principal function is to mate with the Queen, after which they die.  They have very strong wings and in some species they use these to regulate the temperature of the hive.  At the beginning of the Winter, when they have outlived their usefulness, the Workers bite their wings off and kick them out of the hive to die of cold and starvation, since they are unable to forage, produce honey or take care or themselves (!)  They have no stinger or ovipositor.

Worker bees are infertile females.  They clean and maintain the hive, raise the young and feed them on royal jelly, guard the hive, forage for nectar and pollen and produce the wax, from special glands, that is used to make the comb and seal the cells.

There are four distinct stages in the life cycle of a honey bee.

The queen, once mated with the drones starts to lay eggs from mid Winter onwards, in temperate climates.

After three days, the egg hatches into a larva and is fed ‘bee milk’ and ‘bee bread’ by the worker bees.  Then it spins a cocoon during days 4 to 9.

In the cocoon, the larva develops into a pupa with eyes, wings and legs.  This developments takes anywhere from 10 to 23 days.

The adult finally emerges from the cell in the comb by chewing its way out.  It metamorphoses into a fully grown bee from days 16 to 24, depending on the caste of bee.

The worker bees, that forage for nectar, have ultraviolet vision which allows her to see patterns on flower petals that draw them in.  The nectar is stored in her honey stomach until she reaches the hive where it is passed to others to store in the comb.  They also use their wings to fan the cells that contain nectar as this is 80% water and by fanning they help to evaporate the water, which means the honey remains in the cells.

They communicate through ‘dances’, but it is believed that they also rely on their olfactory senses once the foragers have been given directions from the waggle dances.

Worker bees have to forage approximately 5.5 million flowers to produce approximately a kilogramme of honey.

Worker bees’ stings are barbed but do not always detach on stinging and bumblebees do not have a barbed sting.  Even if honeybees do lose their sting, they do not necessarily die afterwards.  Most bees are non-aggressive and only sting to protect themselves or the hive, which is why bee keepers use puffs of smoke to calm the bees.

The buzzing sound a bee makes is not caused by the beating of their wings but it is a result of the bee vibrating its flight muscles.  Bumblebees have an especially pronounced buzz as they have to warm up their bodies before they fly when temperatures are low.


Saturday, 1 December 2012

Bees

Bees are flying insects, closely related to wasps and … ants.

They are adpated for feeding on nectar and pollen – nectar is an energy source and pollen is principally used as food for larvae.

The smallest bee is 2.1mm and is a stingless bee.  The largest is 39mm and is a leafcutter bee.

Bees either live in communities, where they perform different tasks, or they are solitary and do not produce wax or honey but are important pollinators of plants.

There are more than 20 000 species of bees divided into 7 or 9 recognised families.

Bees are found on every continent except Antartica.  2 500 species in Europe and between 950 to 1 000 in France.  In France, these are divided into 6 families with 15 sub-groups and more than 50 genuses.

  • Apis mellifera – European or Western honey bees
  • Xylocopa – carpenter bees – one of the largest in Europe
  • Andrena – sand bees – more than 150 species in France
  • Lasioglossum (Halicitidae) – mostly live in the ground
  • Megachile – leaf cutter bees
  • Bourdons – bumblebees

More than half of the bee species in France can be found in the Mediterranean area.

Other types of bees are : sweat bees, mason bees, polyster bees, squash bees, alkali bees, digger bees, cleptoparasitic bees, cuckoo bees and nocturnal bees …

About Bees – the History


Flowers and bees first live in 100 000 000 BC during the age of the dinosaurs.

In 20 000 000 BC honeybees and mammals emerged.

After the Ice Age, ancient people learned how to use smoke to calm bees.

Apiarists believe that the Egyptians were the first beekeepers.  They kept their bees in hives made of clay and mud.

The ancient Greeks studied new ways of raising and keeping bees.

Romans used melted beeswax and dye to paint pictures.

In the Middle Ages, beekeepers started using straw masks and hoods to protect them from bee stings.

Pilgrims brought the first honeybees to America.

There were honeybees in California by 1820.  Pioneers used boxes to trap bees – they followed the bee back to the hive and took the honey.

More recently, scientists have discovered the genes of a bee that lived 25 million years ago and bees have built a honeycomb in zero gravity on a Space Shuttle.

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