GOOD VIBRATIONS
Posted by Phytopath on Jun 26, 2011
Remember that song by the Beach Boys back in the mid 1960’s?
The fact is – insects knew about good vibrations well before the Beach Boys.
Many insects, including cicada, ants, beetles and stink bugs, use vibration to attract sexual partners.
Not much difference to the disco days, when we all gathered at a particular venue to ‘check each other out’ on the dance floor.
Experiments performed by biologist Andrej Cokl on southern green stink bugs, showed female stink bugs provide detailed directions to their male suitors, on where to find them.
This AGPS (Arthropod Geographical Positioning System) uses vibration as its method of transmittance.
Initially, the male releases pheromones to attract the female.
Scent or aroma is not always a precise indicator of the origin of that aroma (unless it is a dead mouse under the refrigerator), so the female sometimes lands on a nearby plant instead of the same plant the male is eagerly waiting upon.
Once the female has landed in the nearby vicinity of the male, she starts to vibrate and send out a type of Morse code, tapping directions to the nearby male.
Cokl noticed that female stink bugs moved an abdominal plate attached to the thorax, in time with the rhythms oscillating through plants (100 hertz pulse every five seconds).
These vibrations move through the plant at speeds between 30 and 100 metres a second.
Flavio Roces of the University of Wurzburg in Germany believes that the difference in arrival time of the vibration between the left and right leg of the stink bug, is an indicator to the bug whether to move left, right, up or down along the branches of the plant.
He also believes that mechanoreceptors on the antennae may also play a part in determining which direction to go.
This constant movement of legs and antennae on the plant must certainly look like a disco dancing dude.
A truly amazing sight.
photo from Wikimedia commons
MULCH
Posted by Phytopath on Jun 19, 2011
The Good, The Bad & The Dangerous.
Gardeners who live in hot climates are used to hearing the advice; mulch, mulch, mulch.
But is it the best thing to do in YOUR garden?
The main types of mulching material are;-
Organic materials which decompose readily. For example, straw, hay, leaves, manures and seaweed.
Organic material that decomposes more slowly, for example, pine bark, wood chips, twigs and thin branches.
Minerals such as pebbles, gravel and crushed bricks, just to name a few.
Synthetic material such as weed mat.
You can also use ground covers as a living mulch.
The idea of using a layer of mulch around your plants or throughout your garden is to reduce the loss of water
from the soil via evaporation.
Mulch can also protect the soil surface from heavy rain and reduce the risk of crusting and erosion.
It can slow the flow of water across the soil surface and increase the amount of water moving down through the soil profile.
Mulch can change the temperature of the soil beneath it and it can sometimes suppress weed growth.
Organic mulches that decompose rapidly also help to improve the soil structure.
All in all, mulching sounds like a good thing to do.
So why is the title of this blog post ‘Mulch. The good, the bad and the dangerous?’
Well, some mulching material can be detrimental to your plants.
If mulch is spread too thickly and forms a watertight layer, it can prevent gases leaving and entering the soil
around plants.
Carbon dioxide levels can build up in the soil and plant roots can ‘suffocate’ from lack of oxygen.
The same situation can occur if you are using plastic mulching material.
Plants may develop Nitrogen deficiency when certain materials, such as sawdust and straw, decompose
rapidly. If you intend using these types of material that are high in carbon, place a layer of nitrogen fertilizer on the soil before applying the mulch.
Mulches can aggravate anaerobic conditions in soil where the drainage is poor. This can lead to denitrification
(loss of Nitrogen) in the soil which will show as a yellowing of older leaves in some plants.
Many types of mulch are used to decrease the soil temperature in hot climates, so the plant roots that are
growing near the surface of the soil don’t ‘cook’. But air temperatures are more extreme just above the mulching material. Young seedling plants growing through a layer of mulch in the summer can be injured by the higher temperature.
The opposite is also true for night temperatures. Organic mulches are not good at absorbing heat during the day and the surface of mulch cools very quickly under night radiation, sometimes being three or four degrees colder above a mulch than above bare soil.
Another factor to watch out for is the possibility of toxicity or phytotoxicity.
Not all plants get along with each other (much like people) and some plants even cause other plants to get really sick if they are in close proximity to each other.
If material that has been designated for mulch has not been composted properly, it can cause toxicity to other
plants once spread around the garden.
Bark and sawdust from certain trees have been reported to be toxic to other plants. Some examples are Eucalyptus, redwood, cedar, larch and spruce.
The toxic substances from these trees can be removed through proper composting. 
So there you have it.
The Good, The Bad and The Dangerous.
A few Gardening Video’s for You
Posted by Phytopath on Jun 3, 2011
