Heat Stress

More Information
Dr David Bromwich is a retired occupational hygienist with an adjunct appointment at Griffith University and gives lectures at other universities.


Gardeners can occasionally suffer from conditions such as prickly heat, heat syncope (fainting) and heat exhaustion. However, heat stress can also kill through heat stroke.

The main predictor of heat stress, the temperature and weather, only tells part of the story. The humidity, air flow over our skin, our pattern of exertion and rest and hydration give a more complete picture. Add to this radiant heat from the sun and surfaces and the picture is almost complete.

Thermoregulation in humans is about keeping the body core temperature – the main organs including the brain – close to 37?C. When we are hot, blood flow to the skin increases and this allows greater loss of heat, particularly when we sweat.


From a 2 page Feature Article in Issue Thirty Three
Heat Stress.
Subscribe Now!

When Your Green Thumb turns Brown
Cynthia Carson
Cynthia Carson


Both casual and committed gardeners alike have experienced dismay at
having plants wilt and die. Should blame be attributed to the plant,
the potting mix, the watering, the climate or the gardener?

These plant deaths are often attributed to either too little or too much moisture in the soil or growing media. Whilst it is correct that severely drought-stressed plants may not be capable of recovery after being watered, and that water-logged plants can die from a lack of oxygen (and sometimes newly-mobilised toxins around the root system), less transient causes of plant loss such as disease, pests, salinity or soil contaminants are also common.

The most commonly encountered causes of permanent wilt are vascular wilts (both infecting and clogging the stem), collar rot (seen on stems near soil level) and root rot. The organisms that cause permanent wilt
are normally fungi or bacteria and more rarely viruses.

Topics covered in this article are:

  • Root Disease: Above ground systems
  • Simple checks
  • Organisms causing permanent wilt
  • General strategies for disease control
  • How to control disease in pots
  • How to control disease in garden beds
    • Solarisation
  • A final word


From a 4 page Feature Article in Issue Thirty Three
Healthy Coprosma repens.
Bag and dispose of infected media.
Even large pots can be scrubbed with warm soapy water.
Subscribe Now!

Garden Calendar
Arno King


After another dry and warm spring in much of Queensland, gardeners are looking forward to the arrival of the wet, and hope that it will arrive early and bring consistent and regular rainfall.

With the rains comes the strong, lush and often colourful growth, which it is hard to achieve even with constant irrigation.

The arrival of the rains in summer signals the ideal time to transplant and to propagate plants from seed, cuttings and division. Rains are generally accompanied by increased humidity, cloud cover and less extreme temperatures. It can also be a much more pleasant time to work in the garden with the soft moist soil making it easier to pull weeds, dig up plants and prepare beds for planting.

Information is given for what to do in each of the months:

  • November
  • December
  • January
  • February

Special information is also provided for:

  • Vegetable planting schedule for November, December, January and February for subtropics and tropics
  • Annual planting schedule for November through February

Also discussed in general is the Vegetable Garden.


From a 7 page Feature Article in Issue Thirty Three
New Zealand Spinach Warrigal Greens (Tetragonia tetragonoides).
Illawarra Flame Tree (Brachychiton acerfolius) normally drops its leaves when flowering.
An enticing display. National Orchid Garden, Singapore.
Subscribe Now!

Ph/Fax 07 5447 6300 | PO Box 406, Eumundi QLD 4562 Australia
© 2005-2015 Subtropicalia Media Pty Ltd T/A Subtropical Gardening – All Rights Reserved   ABN 79 113 106 862